Refrigerant Emissions and Leakage ZERO Project
Training Modules
available:
TRAINING MODULE GUIDE
1 - Environmental, cost
and legal aspects of
refrigerant leakage.
2 - Reducing leakage
through appropriate
maintenance and service.
3 - Minimising leakage in
new systems.
4 - Reducing leakage
through site specific
surveys and advice.
The Carbon Trust works with groups of organisations
to reduce carbon emissions and costs.
www.realzero.org.uk
Sponsored by
Training Module Guide
REAL Zero provides practical guidance to the refrigeration and air conditioning (RAC)
industry to aid refrigerant leakage reduction. It has been funded by the Carbon Trust, the
Institute of Refrigeration and industry and has provided:
•
site specific surveys for a range of end users to show them where leakage can be
reduced and to gather up to date information about compliance with regulations;
•
5 guides for service, maintenance and design engineers, contracting companies and end
users;
•
Calculators to enable the financial and environmental impact of leakage to be
determined;
•
Seminars during the first half of 2009 for RAC engineers and end users to discuss
leakage reduction issues
•
Training for those who want to know more about reducing leakage.
Full details about REAL Zero can be found at www.realzero.org.uk It is strongly
recommended that you visit this site as part of this training.
Leakage reduction training
This training material can be used in several ways. For example:
Person
Recommendation
End result
Service and
maintenance
engineer
Experienced service and maintenance engineers
can study Modules 1 and 2 to enhance and build
on practical skills assessed as part of the City and
Guilds 2079-11, level 2 certificate in F Gas and
ODS regulations or CITB J11.
CPD* certificates for modules 1
and 2 are awarded if they
successfully complete an online
assessments.
Service
supervisor,
project manager
For experienced refrigeration engineers, who
already hold
City and Guilds 2079-11, level 2 certificate in F
Gas and ODS regulations or CITB J11, can
enhance their understanding of how to deliver
leakage reduction strategies by studying all four
Modules.
An online assessment must be successfully
completed for all modules 1, 2 and 3.
CPD* certificates for all four
modules are awarded if they
successfully complete all four
assessments, one of which is a
sample client report.
To join the
listing on the
IOR REAL Zero
website
Be an experienced RAC engineer with practical
experience.
City and Guilds 2079-11, level 2 certificate in F
Gas and ODS regulations or CITB J11.
All modules must be studied.
An online assessment must be successfully
completed for all four modules.
A sample report must be provided for evaluation.
CPD* certificate for all modules.
Inclusion in the REAL Zero listing
showing individuals who have
passed the assessments for these
modules.
Use of REAL Zero site inspection
proformas and standard reports
developed as part of the project
REAL Zero Leak Reduction Training Module Guide
Institute of Refrigeration 2009
page 2
* CPD – Continuing Personal or Professional Development - is the term that
describes a commitment to structured skills enhancement and personal or
professional competence. The Institute of Refrigeration has gained
independent CPD Certification of this training material by the Construction CPD
Service.
The training material is also an invaluable resource for anyone wanting to find out more
about how to reduce refrigerant leakage.
If you wish to obtain Institute of Refrigeration Continuing Professional Development (CPD)
Certification you must register for the complete leakage reduction training course, which
includes four modules, three on line assessment tests and the review of a sample site
survey. The fee for the assessments is £50+VAT. On successful completion of the
assessments will you receive the CPD certificates.
You will also be eligible to join our website list – the fee is normally £100+VAT but has been
waived for those attending a Carbon Trust sponsored workshop - if you have achieved the
CPD Certificates, passed a current F Gas Certificate and are a member of the Institute of
Refrigeration.
See the REAL Zero website training section for details of how to apply for these
assessments and the web listing.
The modules
The training is split into four modules as outlined in the table below.
Module
Topics
Assessment
1
Environmental,
cost and legal
aspects of
refrigerant
leakage.
Approximately 5
hours learning
time
Available as a
free download
1.1. Environmental impact of refrigerants and
systems.
1.2. Calculating the financial cost of leakage.
1.3. REAL Zero calculators.
1.4. Legal obligations under the F Gas regulation.
1.5. Making a case for reduced leakage.
1.6. Generic information about common leak points.
10 multi choice
questions
2
Reducing
leakage through
appropriate
maintenance
and service.
Approximately 5
hours learning
time
Available as a
2.1. System maintenance regimes for minimum
leakage.
2.2. Records for effective refrigerant management.
2.3. Direct leak testing methods.
2.4. Indirect leak testing methods.
2.5. Fixed leak detection systems.
2.6. How to reduce leak potential in existing systems.
10 multi choice
questions
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 3
free download
3
Minimising
leakage in new
systems.
Approximately 5
hours learning
time
Only available
as part of the
complete
training course
of four modules
3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
3.7.
System design basics for minimum leakage.
Key pressures.
Pipe design.
Over pressure protection.
Installation for minimum leakage.
The importance of commissioning.
Fixed leak detection.
4
Reducing
leakage through
site specific
surveys and
advice.
Approximately 5
hours learning
time
Only available
as part of the
complete
training course
of four modules
4.1. Site surveys to identify areas where leakage can
be reduced.
4.2. The correct refrigerant change amount.
4.3. Preparing a strategy for leakage reduction.
4.4. Preparation of reports with recommendations for
leakage reduction strategies.
10 multiple
choice
questions
Sample survey
and report for
evaluation
Setting the scene
Refrigerant leakage is unnecessarily high from many systems. This is due to a number of
factors including:
•
•
•
•
•
•
Type of components and joints used;
Lack of time when installing and commissioning systems;
Poor installation practices, e.g. lack of brazing skills;
Inadequate leak testing as part of planned maintenance;
Poor service and repair of systems;
Lack of awareness or motivation to reduce leakage.
Typical leakage figures are given in the tables below for a number of sectors.
System type
Retail
1
Direct emissions
MTCO2e1
Indirect
emissions
MTCO2e
Total global
warming impact
MTCO2e
% related to
refrigerant
emissions
9.0
23.0
32.0
28%
Mega Tonnes of carbon dioxide equivalent
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 4
Industrial
3.4
25.0
28.4
12%
DX AC
2.6
10.0
12.6
21%
Small
commercial
1.8
12.0
13.8
13%
Chillers
0.7
12.0
12.7
6%
Other small
hermetic
0.3
12.0
12.3
25
From March Consulting Group. 1998, Opportunities to minimise emissions of hydrofluorocarbons (HFCs) from
the European Union, Report for DGIII-C-4 of the European Commission
Sector
Leak rate
Typical ref charge
Number systems
Retail integral
cabinets
<1%
<3kg
4,000,000
Small commercial
<1%
3 to 30kg
300,000
Supermarkets
20 to 30%
30 to 300kg
50,000
Industrial
15 to 20%
>300kg
50,000
Air conditioning
15 to 20%
>30kg
420,000
From Institute of Refrigeration Annual Conference 2005.
There is no one simple solution to leakage reduction. All the following contribute to
minimising leaks:
;
;
;
;
;
;
;
;
;
;
Design systems with minimal joints using components which are know not to leak
excessively (module 3);
Route, support and clamp pipe work correctly (module 3);
Install adequate vibration isolation (module 3);
Ensure brazers are competent and qualified (module 3);
Pressure leak test systems to the correct standard (module 3);
Charge systems with the correct amount of refrigerant (modules 2 and 3);
Install fixed leak detection where necessary (module 2 and 3);
Carry out planned preventative maintenance to minimise head pressure and ensure
systems are operating at the optimum level (module 2);
Carry out sufficient leak testing and repair leaks where necessary (module 2);
Improve service practices, including replacing caps after service, tightening flanges
correctly and replacing gaskets where necessary (module 2).
Each of these is covered in detail in the training modules indicated.
It is assumed that you have already completed a City and Guilds 2079 - 11 (for
category 1 engineers) level 2 certificate in F Gas and ODS regulations or the CITB
equivalent. This training package builds on the knowledge and skills covered in
these qualifications, but does not repeat it.
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 5
Appendix 1 – Accessing the Self Study Modules
1. What do I need to do?
These are included in this pdf document. You can also download further copies of individual modules
from the www.realzero.org.uk website YOUR REAL ZERO TOOLKIT. Each booklet gives you an idea
of how much time you should spend studying the material and offers some questions and interactive
exercises for you to test your own knowledge.
2. What is covered?
• Module 1 - Environmental, cost and legal aspects of refrigerant leakage.
• Module 2 - Reducing leakage through appropriate maintenance and service.
• Module 3 – Minimising leakage in new systems
• Module 4 – Reducing leakage through site specific surveys and advice
• Use of emissions calculators and monitoring tools
3. Can I get recognition for this training?
You will received Institute of Refrigeration Continuing Professional Development (CPD) Certification if
you have successfully completed assessments for each of the four modules.
4. How can I join the REAL Zero website of advisers?
You can only join the website list if you have achieved all four CPD Certificates, passed a current F
Gas Certificate and are a member of the Institute of Refrigeration (any grade).
5. Terms and Conditions of Use
The REAL Zero self study booklets are provided for individual use only. They remain the copyright of
the Institute of Refrigeration. Users of this material undertake not to reproduce, distribute or re-sell.
The booklets may not be used as the basis of training courses unless prior permission is obtained
from the Institute of Refrigeration.
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 6
Appendix 2 - Assessment Guidelines
1. Entry requirements
Candidates are expected to be able to demonstrate their experience in the industry by being a
member of the Institute of Refrigeration (or IOR service engineers section) and must have achieved a
City and Guilds 2079 - 11 (for category 1 engineers) level 2 certificate in F Gas and ODS regulations
or the CITB J11.
2. On line assessments (Modules 1,2 and 3)
2.1The assessment is an on line multiple choice test with 10 questions for each module. The
approximate time required to take the assessment for each module is 30 min. Some assessment
questions will require candidates to undertake calculations, and you should bring a calculator, pen
and note paper. Feedback on whether you have passed will be immediate.
2.2The pass mark for each of these assessments is 80 % (8 out of 10 questions must be answered
correctly). Candidates will be entitled to retake assessments within a limited time period. When you
have successfully completed a Module you will automatically be issued with an IOR CPD Certificate
(Continual Professional Development) independently endorsed by the Construction CPD Service.
3. Completing Module 4 – Reducing leakage through site specific surveys and advice
The assessment for Module 4 requires the submission of a site survey and advice report. The details
of how the survey should be carried out and advice reports drafted is included in the self study
module. Your report will be evaluated by an IOR assessor and the results will be returned with a
detailed commentary. Reports must be submitted electronically to ior@ior.org.uk and you should
allow approximately two weeks for results to be returned to you with your CPD Certificate (if
successful). You may only apply for assessment of Module 4 once you have successfully completed
modules 1, 2 and 3.
4. Assessment and certification fees
The fee of £50+VAT covers all four assessments and certificates. No refunds will be offered for
partial completion, withdrawal from or failure to pass the assessment. Duplicate certificates will only
be issued at an additional charge.
5. The right to withdraw certificates
The IOR reserves the right to withdraw certificates if these Guidelines are not adhered to or if
candidates were found to be fraudulent in their undertaking of the assessments.
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 7
Appendix 3 - Joining the REAL Zero website
1. Who should apply to join the website list of advisors?
There is growing demand from equipment owners to get more detailed advice on how they can
reduce costs related to refrigerant use and implement effective refrigerant leakage reduction
strategies. A section on the REAL Zero websites provides a list of individuals and companies who
can offer this advice. The REAL Zero advice goes beyond the basic minimum standard required by F
Gas Regulations. The listing is open to those who have:
• successfully completed all of the REAL Zero training and assessment modules
• are members of the Institute of Refrigeration (any grade)
• have achieved an F Gas refrigerant handling qualification (City and Guilds 2079 - 11 category
1in F Gas and ODS regulations or the CITB J11).
This is a benefit for those who wish to market this enhanced service to customers, to show their
commitment to taking practical and persuasive actions to aid leakage reduction.
Those who join make a commitment not just to advise customers on leakage reduction as part of a
one off survey of their equipment, but to help the customers to implement the strategies
recommended and monitor the savings achieved.
2. What are the benefits of joining?
By undertaking and successfully completing the Leakage Reduction training course you will have
developed and reinforced your skills in this important area. The additional benefits of becoming
registered as a leakage reduction adviser include:
ƒ Your details will be included in the list of refrigerant leakage advisers on the REAL Zero
website
ƒ You will be authorised to use the REAL Zero logo in your marketing material and
communications
ƒ You will be able to use the REAL Zero site survey methodology and proforma client reports to
provide authoritative advice to RAC system operators and owners on how to reduce
refrigerant leakage and help minimise environmental impact and costs.
ƒ Your clients will have the assurance that your site surveys have been undertaken in
accordance with IOR developed procedures and that your advice and recommendations
conform with an established set of industry guidelines
ƒ You will be promoting good practice in the RAC industry and helping to improve the
environment enhancing the sustainability of RAC systems
ƒ The IOR will keep you updated on refrigerant leakage issues as new information and
materials become available
ƒ The scheme is backed by the Institute of Refrigeration, the UK’s leading membership
organisation for RAC professionals
3. What does it cost to join?
The standard fee to join the list is £100 + vat and is renewable after 12 months at £50 + vat. The
joining fee has been waived for those attending a Carbon Trust sponsored workshop. In order to
qualify for renewal you must also provide a confidential summary report of site surveys undertaken
and estimated carbon savings, at least once every half year.
4. How do I join?
Apply on line or using the application from sent with your acknowledgement to the Institute of
Refrigeration together with payment and evidence of the necessary documentation to join the listing.
In applying to join the listing you are agreeing to the terms and conditions below. Please read these
carefully before completing the application form.
5. Terms and Conditions of joining the REAL Zero website listing
All applicants must provide evidence of the following:
1. REAL Zero assessment CPD certificate for successful completion of all four training Modules
2. C&G 2079 Category 1 or CITB J11
3. IOR membership
4. Valid address and contact details
5. The name of their company and its consent in writing if you wish to list your affiliation
By applying to join the website listing you undertake to:
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 8
•
•
•
•
Apply REAL Zero knowledge to help reduce refrigerant leakage and emissions
Provide clear acknowledgement of REAL Zero source material and reports
Provide accurate and reasonable data to clients
Submit summary data from site surveys undertaken in the required format which will include
estimates of resulting emissions saving activity carried out by the site. (All data will be treaded as
confidential, identifying information of customers should be removed. The data will be used to
evaluate the ongoing achievements of the REAL Zero project and summary data only will be
shared with the Carbon Trust.)
• Provide copies of complete site surveys and request follow up reports from sites as and when
required by the Institute of Refrigeration for auditing purposes
• Pay the registration fee and annual renewal fees if appropriate
• Inform the IOR if you change employment or any other relevant personal circumstances change.
• Obtain your company’s consent in writing if you wish your affiliation to be shown
The Institute of Refrigeration undertakes to:
• keep accurate information about individuals/companies on its website and promote this
service to the refrigeration community and end users
• provide updates and keep those listed informed of news about leak reduction and REAL zero
initiatives
• keep additional personal and client information confidential
• carry out PR and advertising of the REAL Zero advice service to promote this to the operators
of equipment
• provide those on the REAL Zero list with the right to use the REAL Zero in marketing material
Note: the Institute of Refrigeration reserves the right to withdraw individuals or refuse to renew if these
terms and conditions are not met
REAL Zero Leak Reduction Training Module Guide (Carbon Trust workshop)
Institute of Refrigeration April 2010
page 9
Refrigerant Emissions and Leakage ZERO Project
Environmental, Cost and
Legal Aspects of Refrigerant Leakage
Training Modules
available:
TRAINING MODULE 1
1 - Environmental, cost
and legal aspects of
refrigerant leakage.
2 - Reducing leakage
through appropriate
maintenance and service.
3 - Minimising leakage in
new systems.
4 - Reducing leakage
through site specific
surveys and advice.
The Carbon Trust works with groups of organisations
to reduce carbon emissions and costs.
www.realzero.org.uk
Sponsored by
Module 1
Environmental, Cost and Legal Aspects of Refrigerant Leakage
This module outlines the environmental and cost impact of refrigerant leakage. It shows
how you can equate refrigerant leakage to other environmentally damaging activities to
provide an indication of the scale of damage caused by refrigerant leakage. This type of
information is key in building a persuasive business case for reducing leakage of refrigerant
and thus improving business profitability.
This module also outlines the legislation covering HFC and HCFC refrigerants and shows
how you can check compliance. Generic information about leakage is provided to give an
introduction to later modules which show how to reduce leakage through good design,
installation, service and maintenance.
By the end of this module you will understand:
•
•
•
•
•
The direct and indirect environmental impact of refrigerants;
The concept of carbon dioxide equivalent;
The scale of refrigerant leakage;
Why and where leaks occur;
Legal obligations under the F Gas and ODS regulations.
and be capable of:
•
•
•
•
•
Relating refrigerant leakage to other environmentally damaging activities;
Calculating the financial impact of leakage;
Building a business case for reducing leakage;
Applying the Real Zero calculators;
Auditing compliance with F gas and ODS regulations.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 2
1.1 Environmental Impact of Refrigerants and RAC Systems
Leaking refrigerant has a double impact on climate change:
•
•
A direct effect if the refrigerant has a global warming potential;
An indirect effect because of the increase in power consumption.
Increases costs –
service, refrigerant,
electricity, downtime
Leaking
refrigerant
Increases adverse
climate change
- the “direct” effect
Reduces system efficiency
Increases power consumption
Increases CO2 emissions
(at the power station)
Increases adverse climate change
- the “indirect” effect
The total carbon emissions of a system include both the effect of leaking refrigerant and the
power consumption of a system. The next section shows how this is calculated.
Natural refrigerants have a very low direct impact on climate change, typically a few
thousandths that of the HFCs. Natural refrigerants include:
•
•
•
HCs - hydrocarbons such as propane (R290), propylene (R1270) and isobutane
(R600a);
CO2 (carbon dioxide, R744);
NH3 (ammonia, R717).
They are increasingly used but have challenges which limit where they can currently be
used, as shown in the table below.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 3
Refrigerant
Applications
Issues
HCs
Started to be used in the 1990s.
Domestic fridges.
Integral commercial systems such
as ice cream freezers, bottle
coolers and catering fridges.
Packaged chillers.
Flammable, so are generally
limited to small charge systems or
close coupled packaged systems.
CO2
Started to be used from about 2005
in the UK.
Industrial systems, e.g. distribution
cold stores.
Retail central plant systems.
Data centre cooling.
Heat pumps.
Split and VRV / VRF air
conditioning systems.
Integral systems such as bottle
coolers and vending machines
(development stage only).
High pressures.
Typically more complex systems
design.
Increased engineer skills and
knowledge required.
NH3
Used for 150 years.
Industrial systems.
Toxic and flammable.
Global warming potential (GWP)
The global warming potential (GWP) of a refrigerant is a measure of how much a given mass
of greenhouse gas (e.g. HFC refrigerant) is estimated to contribute to global warming. It is a
relative scale which compares the gas in question to that of the same mass of carbon
dioxide (whose GWP is by definition 1). A GWP is calculated over a specific time interval
and the value of this must be stated whenever a GWP is quoted or else the value is
meaningless.
Substances such as HFCs which have a high GWP tend also to absorb a lot of infra red
radiation and have a long atmospheric lifetime.
GWP and carbon dioxide equivalency
Carbon dioxide equivalency is a quantity that describes, for a given mixture and amount of
greenhouse gas, the amount of CO2 that would have the same global warming potential
(GWP), when measured over a specified timescale (generally, 100 years). The carbon
dioxide equivalency for a gas is obtained by multiplying the mass and the GWP of the gas.
The following units are commonly used:
•
•
•
kg of carbon dioxide equivalents (kgCDE).
tonnes of carbon dioxide equivalents (TCDE).
million tonnes of carbon dioxide equivalents (MTCDE).
For example, the GWP for R290 (propane) over 100 years is 3 and for R404A is 3260. This
means that a leak of:
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 4
• 1 tonne of R290 is equivalent to emissions of 3 tonnes of carbon dioxide.
• 1 tonne of R404A is equivalent to emissions of 3260 tonnes of carbon dioxide.
The GWP of the common refrigerants is shown in appendix 1.
Calculating the environmental cost of leakage
The direct impact of leakage on climate change is calculated simply by multiplying the GWP
of the refrigerant by the amount which has leaked in a given time. The example below
shows how this has been calculated from the information in an F Gas log (see Module 2
Section 2.2 for more information about this important log). Note: this is the minimum
information necessary as suggested by DEFRA F Gas Support - the Real Zero refrigerant
monitoring tool, which can be downloaded from the Real Zero website provides additional
features.
RECORD SHEET FOR F-GAS REGULATION
General Information
Plant Name HT pack
Reference No. HT 2
Location of plant XXXXXXX stores, Cheltenham
Plant Operator XXXXXXX
Operator Contact XXXXXXX
Cooling loads served 22 HT cabinets (20 to 41) and 1 cold room
Refrigerant Type R404A
Refrigerant Quantity (kg)
Plant manufacturer XXX
Year of installation 2002
65
Refrigerant Additions
Date
Technician/Company
20.01.2008
XXX
09.03.2008
XXX
14.07.2008
XXX
Refrigerant Removals
Amount Added, kg
22 kg
65 kg
35 kg
Reason for addition
Top up after leak
Re charge after compressor change
Top up after leak
Date
Technician/Company
Amount Removed, kg
09.03.2008
XXX
65 kg
Reason for removal. What was done with
recovered refrigerant
Compressor change, refrigerant sent for
recycling
Date
Technician/Company
09.03.2008
XXX
14.07.2008
XXX
Test Result (including location and
cause of any leaks identified)
Leaks at liquid line schrader valve
on roof and TEV inlet in cold room
evaporator 1
Leak found on drier flange
10.09.2008
XXX
Leak Tests
Follow up actions required
Schrader capped and re
tested, flare connection to
TEV re made
Replaced flange gasket and
tightened flange
Routine leak test for whole plant –
no leaks found
Follow-up Actions
Date
27.01.2008
Technician/Company
XXX
Related to test on
20.01.2008
21.07.2003
XXX
14.07.2008
Actions Taken
Leak tested liquid line Schrader and TEV in
cold room - OK
Leak tested drier flange - OK
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 5
The total amount of refrigerant which has leaked from this system in 2008 is the total amount
charged in less the amount recovered:
(25 + 65 + 35) – 65 = 60 kg.
The carbon dioxide equivalent for this is:
60 x 3260 = 195,600 kgCDE, or 195.6 TCDE.
This is an annual leak rated of 92% of the charge. You can see from the information in the
Module Guide that this is significantly higher than the typical leak for this type of system (20
to 30%).
Comparing refrigerant leakage to other environmentally damaging activities
It is useful to relate the impact of refrigerant leakage to other activities which impact on
climate change, such as driving a vehicle. You need to know some key figures to be able to
do this – these are provided in the next three tables.
Conversion to CO2 (gross CV basis 1)
Fuel
Units
kgCO2 / unit
Grid electricity
kWh
0.537
Natural gas
kWh
Therms
0.185
5.421
LPG
kWh
therms
litres
0.214
6.277
1.495
Gas oil
tonnes
kWh
litres
3,190
0.252
2.674
Fuel oil
Tonnes
kWh
3,223
0.268
Burning oil (kerosene or
paraffin)
Tonnes
kWh
3,150
0.245
Diesel
tonnes
kWh
litres
3,164
0.250
2.630
Petrol
tonnes
kWh
litres
3,135
0.240
2.315
Industrial coal
tonnes
kWh
2,457
0.330
Wood pellets
tonnes
kWh
132
0.025
1
Emissions factors are calculated on a gross calorific value (CV) basis as generally quoted by energy
supplier.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 6
Petrol and diesel vehicles
kg CO2 / mile
kg CO2 / km
1.4 to 2 litre petrol engine
0.3442
0.2139
Over 2 litre petrol engine
0.4760
0.2958
Average petrol car
0.3332
0.2070
1.7 to 2 litre diesel engine
0.3027
0.1881
Over 2 litre diesel engine
0.4153
0.2580
Average diesel car
0.3185
0.1979
Mode of public transport
kg CO2 / passenger km
Average bus and coach
0.0686
National rail
0.0602
Long haul international flight
0.1206
Short haul international flight
0.1071
Domestic flight
0.1911
The information in these tables is from a Carbon Trust fact sheet CTL018, Energy and
conversion factors available from
http://www.carbontrust.co.uk/resource/conversion_factors/default.htm
This information allows you to compare the impact of climate change of refrigerant leakage
to activities such as driving a vehicle, flying, running an appliance etc. Some examples are
shown below.
Comparing leakage to driving a service van
A typical service van produces 0.3027 kg CO2 / mile driven.
So 1 kg CO2 is produced every 1 / 0.3027 miles = 3.3 miles.
R404A has a GWP of 3260, i.e. 1kg of R404A has the same effect as 3260 kg CO2.
So … 1 kg R404A = 3260 kg CO2 = 3.3 x 3260 service van miles = 10,770 miles.
A leak of 2.5 kg R404A is the same as driving a service van once around the world.
This is a very useful comparison to highlight the impact of refrigerant leakage.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 7
Comparing leakage to electricity consumption
A mid range Bosch fridge uses 139 kWh electricity per year.
1 kWh of electricity produces 0.537 kg CO2.
So 1 kg R404A has the same impact as running the fridge for 44 years
Calculated from 3260 / (139 x 0.537).
Note – so far we have only considered the direct effect of leakage, not the indirect effect
caused by less efficient operation of a system which is under-charged. This is covered in
the next section.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 8
1.2 The financial cost of leakage
It is very difficult to accurately calculate the total financial cost of leakage. The following
contribute to the cost:
•
Refrigerant – easy to calculate from the buying price of the refrigerant and the amounts
used (note – buying prices vary significantly and depend on the discount provided by the
supplier);
•
Cost of labour to find and repair the leak and re charge with refrigerant – this should be
easy to find from the service records but there will be a wide range as the work that
needs to be carried out to fix a leak varies significantly depending on the location of the
leak;
•
Additional running cost of the system due to under charge of refrigerant – very difficult to
estimate as the profile of energy consumption vs. charge amount varies with different
systems and there is very little practical data available. A simple example is given
below;
•
Downtime – some end users have this information, but it varies significantly.
The costs will vary depending on how quickly the leak is found and repaired, as shown in the
diagram below.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 9
System running cost
There is no simple correlation between leakage and energy efficiency - the impact of
refrigerant leakage on energy consumption varies widely depending on the system:
System type
Impact of leakage
Small system with no liquid
receiver (i.e. a critically
charged system), e.g. many
integral systems, split AC
systems.
A loss of just 5% of the charge will reduce the efficiency
because the refrigerant in the liquid line will be saturated
rather than sub cooled, so less liquid refrigerant will flow into
the evaporator. This reduces the suction pressure and the
saturated evaporating temperature. A drop of 1OC in
evaporating temperature will reduce efficiency (and increase
electricity consumption) by between 2 and 4%.
Simple condensing unit
evaporator systems with a
liquid receiver, e.g. small
retail systems, cold room
systems, liquid chillers.
The receiver contains a buffer of refrigerant which is only
required at extreme operating conditions (e.g. maximum load
and maximum ambient). Once this buffer has leaked the
effect is similar to that outlined above. The time taken to
reach the critical charge will vary depending on the degree of
leakage, load and ambient. While the buffer is leaking there
is no effect on energy consumption.
Central plant systems with
multiple compressors and
evaporators, e.g. large
supermarket systems,
industrial plant.
As with the simple system above the receiver buffer will leak
before there is an effect on performance. At this point the
furthest evaporator from the pack will receive insufficient
refrigerant and the solenoid valve will be open longer to get
the desired refrigeration effect. As the leakage continues
more evaporators will be starved. The effect is that the
pack will run longer to provide the same cooling effect.
The graphs below show the results of research on one system type to determine the effect of
leakage on one system:
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 10
Grace, I.N., Datta, D. and Tassou, S.A. (2005), Sensitivity of refrigeration system
performance to charge levels and parameters for on-line leak detection. Applied Thermal
Engineering, 25 (2005), pp. 557–566
The example below is for a simple single condensing unit single evaporator system. It is a
low temperature cold room with a load of 10 kW. The system has the following operating
conditions when fully charged:
Evaporating temperature of -25OC,
5 K useful superheat,
-15OC suction return temperature,
7K liquid sub cooling
Condenser temperature difference (TD) of 10K.
The table below shows the performance data and annual cost for the system running at the
design conditions fully charged, and at the likely operating conditions when it is
undercharged. It has been assumed the evaporating temperature drops to -28OC and that
there is no liquid sub cooling. The data has been obtained from the selection software
provided by the condensing unit manufacturer, which has the capability of calculating annual
running cost for the local ambient temperature profile (London in this case).
Fully charged system
Under charged system
Capacity, kW
12.9
9.9
Power input, kW
8.2
8.0
COP
1.56
1.24
Annual running cost
£4580
£5564
COP (Coefficient of Performance) is capacity / power input.
Capacity, power input and COP are at the design conditions.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 11
An electricity cost of £0.14 per kWh has been used.
The undercharged system will not meet the load at the design condition (maximum ambient),
so at this point the cold room temperature will rise.
The increase in cost is 21%, or £984 if the system remains undercharged for 1 year.
To accurately determine the increase in cost for a leak on this type of system you would
need to know:
•
•
•
•
•
Design operating conditions;
Operating conditions when undercharged (this is likely to change as the leak continues);
Length of time the system has been undercharged;
Effect on operating conditions of under charge of refrigerant;
System / compressor data, ambient temperature profile and load profile to calculate the
performance and running cost of the system fully charged and under charged.
For many systems this information is not all available, but often an estimate can be made on
the basis of that shown above.
Systems operate inefficiently for many reasons and there is often the opportunity to improve
systems efficiency by simple, cost effective measures. These are outlined in five Guides
available for the Institute of Refrigeration website at
http://www.ior.org.uk/ior_general.php?r=ANG5A3EG
In particular the following two guides will be helpful in reducing running costs of existing
systems:
•
•
Operational efficiency improvements for refrigeration systems;
Results of site investigations.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 12
1.3 REAL Zero Calculators
There are two calculators on the REALZero website which will help to calculate the
equivalent carbon emissions of refrigerant leakage.
These tools can be:
•
•
•
•
•
Used to provide carbon equivalents for refrigerant leakage;
Used to calculate and present the rate of refrigerant leakage as a % of total charge;
Supplied to customers who are not already logging refrigerant and leak tests in
accordance with the F Gas regulation or who want to improve their records;
Used as a reference “library” for guides related to efficiency and leak reduction;
Included in reports to customers following site surveys.
Refrigerant Monitoring spreadsheet
This spreadsheet can be used for monitoring of HFC refrigerant usage and leak tests in
accordance with the F Gas Regulations. DEFRA have suggest a sample basic page F Gas
Log and based on this, the REAL Zero project has added information about the GWP of the
refrigerant. It also includes links to the Real Zero and energy efficiency guides, and other
useful websites.
The application and use of this tool is covered in Module 2.
Carbon Emissions Calculation Tool
The carbon calculator measures the direct effect of refrigerant release in terms of equivalent
CO2 emissions for a wide range of common refrigerants using an in-built library of GWP
values. It also estimates the financial cost of any refrigerant release such as the value of
replacement refrigerant and other associated repair costs. It is flexible enough for users to
enter specific additional costs related to how their business operates or they can use some
standard figures as a rule of thumb.
Using the Carbon Emissions Calculation Tool
You should familiarise yourself with both tools and use them for compiling recommendations
to customers to reduce leakage.
The tool does two things:
•
Quick calculation of the equivalent CO2 emissions resulting from the direct release of
refrigerants into the environment.
•
The approximate cost implications of refrigerant leakage, including:
o cost of refrigerant
o cost of repair
As an exercise you should either use the tool to provide CO2 emissions and costs for a
system you have refrigerant leakage data for, or input the following data:
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 13
Site name – XY Retail
System name – HT1
Refrigerant – R404A
Next
The next screen includes a default refrigerant cost per kg. This is a typical cost but is
unlikely to be accurate for most systems because of the very wide variation in discounts.
You can change this to an actual cost. For the purpose of this exercise leave it at the
default value.
Number of refrigerant additions – 2
Next
Date – 04/04/2008
Quantity of refrigerant added – 60 kg
Reason for addition – routine maintenance top up
Confirm
You now have the opportunity to add a cost for the routine top up. If this is already included
in a comprehensive maintenance contract there will be no additional cost (this is the default).
If not, you can add the cost here. For this exercise leave the cost at 0.
Date – 11/08/2008
Quantity of refrigerant added – 135 kg
Reason for addition – catastrophic leak top up
Confirm
You now have the opportunity to include the cost of the catastrophic leak repair. Again
there is a default value but this is unlikely to be accurate due to the very wide variation in
costs, so if you can add the correct cost here. For this exercise leave it at the default value.
Next
You will now get the final screen showing estimated costs and emissions for the system over
the period covered by the refrigerant additions and projected over the next 10 years if the
system leakage remains constant. Refrigerant leakage is unlikely to remain constant even
with no reduction strategy in place, but this figure will give an idea of the magnitude of the
problem over the life of the system.
In this case the impact of the leaks over the period logged is:
•
•
737100 kgCDE
£3634.60
Note – the calculator shows this as a 7 month period, because that is the period of the
records used, but in reality this is the records for a calendar year.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 14
If you press the “print screen” button on your computer you can paste the screen into a
document.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 15
1.4 Legal obligations under the F Gas regulations
International and European regulations aim to reduce emissions of greenhouse gases such
as HFCs. The Kyoto Protocol is an international environmental treaty produced at the
United Nations Conference on Environment and Development. It is intended to achieve
"stabilization of greenhouse gas concentrations in the atmosphere at a level that would
prevent dangerous anthropogenic interference with the climate system." Key facts are as
follows:
•
•
•
It establishes legally binding commitments for the reduction of greenhouse gases,
including carbon dioxide and HFCs;
Industrialized countries agreed to reduce their collective GHG emissions by 5.2%
compared to the year 1990:
o This includes an 8% reduction for the European Union;
As of 2008, 183 parties have ratified the protocol.
Since signing this treaty the European Union has introduced the Fluorinated Gas regulation
(EC Regulation 842/2006).
Very good practical information about this regulation is provided by F Gas Support. You
should read the following guides produced by this government funded team:
•
•
•
•
•
•
•
•
•
•
•
•
F Gas Support – Introductory Leaflet
RAC 1 – Overview
RAC 2 – Usage
RAC 3 – Key Obligations
RAC 4 – Getting Started
RAC 5 – Qualifications and Certificates
RAC 6 – Practical Guidance
GEN 1 – Glossary
GEN 2 – Fluid Uses
GEN 3 – Markets and Equipment
GEN 4 – Relevant Legislation
GEN 5 – Refrigerant Quantity
These are available from:
www.realzero.org.uk
www.defra.gov.uk/fgas
0161 874 3663
fgas-support@enviros.com
The F Gas Support information also covers the Ozone Depleting Substance (ODS)
Regulation 237/2000.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 16
Auditing compliance with F Gas and ODS Regulations
There is a range of requirements under the F Gas and ODS regulations. It is obligatory to
comply with these – they are summarised in the following table.
F Gas regulation for HFC refrigerants:
Leak tests
Annually for systems between 3 (6kg if the system is hermetically
sealed) and 30 kg charge.
Twice a year for systems over 30 kg charge.
Fixed leak
detection
Required for systems over 300 kg charge. Records should show this
has been checked annually.
Recovery
Refrigerant recovery required during service and maintenance and at
end of life.
Records
Required for systems over 3 kg charge to record refrigerant usage and
leak tests.
Qualifications
Personnel who handle refrigerant must hold the appropriate
qualification.
Labeling
Systems installed after 01.04.2008 must be correctly labeled.
ODS regulation for HCFC refrigerants:
Phase out
Virgin HCFCs not to be used to service systems after 31.12.2009.
Recycled HCFCs not to be used after 31.12.2014.
Leak tests
Annual leak test required for systems over 3 kg charge.
Recovery
Refrigerant recovery required during service and maintenance and at
end of life.
Training
Personnel who handle refrigerant must hold the appropriate
qualification.
Refer to the F Gas Support documents for detailed information.
The checklists in Appendix 2 are a simple way of checking and recording compliance and
can be used in reporting to customers.
You will need to carry out a visual check of the system and have access to the following
information (which should be readily available from the contractor if not on site) to check
compliance:
•
•
•
F Gas records (see section 1.3 and module 3 for more information);
The service and maintenance records;
A list of engineers who have accessed the system / handled refrigerant with their
qualifications.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 17
1.5 Making a case for reduced leakage
Reducing leakage makes business, financial and environmental sense.
The benefits to business include:
;
;
;
;
Compliance with legislation including the F Gas regulation;
Improved “green” credentials;
Reduced production down time / increased sales fixture availability / improved staff
comfort as a result of improved reliability;
Less health and safety risk from refrigeration or air conditioning – directly from refrigerant
emissions and, for food applications, indirectly as a result of improved reliability.
In addition there are financial benefits:
;
;
;
;
Less refrigerant cost;
Less service cost;
Lower costs associated with plant down time;
No loss of energy efficiency associated with reduced refrigerant charge.
These costs may need to be offset against increased maintenance or some additional capital
expenditure, but usually the difference is positive.
The environmental benefits are in parallel with the benefits identified above and include:
;
;
Lower emissions of powerful greenhouse gases (HCFC and HFC refrigerants);
More efficient operation of RAC systems and hence lower emissions of CO2 at the power
station.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 18
1.6 Generic Information about Common Leak Points
Leakage can be split into two categories:
•
•
Catastrophic leakage, usually as a result of stress or external damage;
Gradual leakage, often intermittent or variable in leak rate depending on temperature
and pressure.
The information below is from the Real Zero guide “13 Common Leak Points” which provides
information about leakage from systems.
Leak point
Likely causes
Solutions
1. Shut-off and ball valves
•
Wear of the
packing gland
between the valve
body and spindle
shaft as it
becomes
compacted with
age and use.
Overheating
during installation.
Caps not fitted.
•
Ensure that the gland is
tightened.
•
Wrap the valve with a
damp rag while brazing.
Valve cores
damaged during
brazing.
The cores not
tightened
correctly during
replacement.
Deterioration of
internal seals
over time.
Caps not fitted or
have no O-ring
seal.
•
•
•
2. Schrader valves
•
•
•
•
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
Always cap
valves – most
leaks occur at
uncapped
valves.
•
•
Remove the core when
brazing the fitting in;
ensure the valve body
has cooled before
replacing the core.
Use the correct tool to
replace / tighten the core.
Ensure the cap is fitted
and has a seal (in good
condition) in place.
page 19
3. Flare joints
•
•
•
•
4. Mechanical joints and flanges
•
There are a variety joints and flanges on
a system e.g. drier core lids etc.
•
•
•
Loosening of the
flare nut due to
thermal
expansion /
contraction due to
a wide
temperature
variation,
especially where
those at the outlet
of expansion
valves.
Poor joint
preparation
(causing leakage
from initial
installation).
Over tightening,
leading to
damage at the
copper flare face
and the flare nut.
Under tightening
of the flare.
Where possible, avoid using
flare connections. If they
cannot be avoided:
• Use flare solder adaptors
(factory produce flares).
Ensure the copper seal is
located correctly.
• If you have to make a
flare, cut the pipe work
with a pipe cutter and deburr using the correct
tool. Use an eccentric
flaring tool and ensure the
correct amount of pipe is
protruding through your
flaring block.
• Check the flare size and
that it does not foul the
flare nut on the pipe.
• Lubricate the flare and
nut face with a small
amount of refrigeration
grade oil.
• Don’t over or under
tighten the flare nut – use
a torque wrench to the
setting provided by the
equipment manufacturer.
Incorrectly
prepared joint
Not replacing
gaskets.
Uneven
tightening of
flanges.
Incorrect torque
used for
tightening bolts.
•
•
•
•
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
Avoid using PTFE on
HFC refrigerants - use an
appropriate thread
sealant
Replace gaskets on
flanges and remove all
the old gasket material
before applying the new
one.
Tighten flanges down
evenly applying the
‘opposites’ rule until the
flange is seated correctly.
Use a torque wrench to
carry out the final
tensioning of flange bolts.
page 20
5. Pressure relief valves (PRVs) and
fusible plugs (over-pressure
protection)
•
•
6. Shaft seals (open type
compressors)
•
Fusible plugs –
wide temperature
and / or pressure
variations weaken
the bond between
the solder core
and the plug.
PRVs - do not
reseat when the
pressure drops
after release and
often leak across
the PRV seat
during normal
operation.
General wear
over time,
indicated by an
increased oil loss
from the shaft
seal or refrigerant
leakage.
•
Lubrication
failure.
•
Incorrect fitting of
a new shaft seal.
•
Incorrect shaft
alignment.
•
Excessive
crankshaft end
float or bearing
damage.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
Fusible plugs
•
Where possible, avoid
using fusible plugs. If
possible, replace them
with a PRV.
•
Always leak test fusible
plugs.
PRVs
•
Always leak test the
outlet of PRVs.
•
If a PRV is leaking
replace it with an
equivalent rated device.
•
Do not cap the PRV if it
is leaking.
•
Use dual PRVs with a
change over valve where
possible.
•
Use a bursting disc in
conjunction with the PRV
where possible. It forms
part of the PRV assembly
and often has a tell tale
gauge to indicate rupture.
•
Regular observation of oil
leakage rate into shaft
seal collection vessel to
check oil loss does not
increase.
•
Leak testing of the shaft
seal with the compressor
switched off.
•
Using the correct type of
shaft seal and following
the proper procedure
when replacing the shaft
seal.
page 21
7. Condensers
condensers continued
Shell and tube
condensers
• Corrosion of the
copper and mild
steel if the water
circulating in the
tubes is not
treated correctly.
Leaks can be
particularly hard
to locate, as they
cannot be seen –
refrigerant might
be detected in the
water, but usually
the leak is only
detected by
carrying out a full
pressure test of
the system.
Air-cooled
condensers
•
•
•
8. Line tap valves
•
Shell and tube condensers
• Ensure adequate
corrosion prevention
scheme is in place e.g.
chemical dosing.
• Regular inspection to
monitor potential
corrosion level.
• Regular maintenance
and monitoring. Where a
leak has occurred in the
tube bundle it is often
false economy to replace
one tube, as the rest of
the tubes are probably in
a similar condition and
will fail.
Air cooled condensers
•
•
Always position
condensers on a level
base.
Repair or replace out of
balance fans.
Check the fin block for
signs of oil.
When replacing a
condenser, select it
carefully, especially if it is
going into an aggressive
environment e.g. on the
coast.
Corrosion due to
aggressive air.
Impact damage
due to foreign
bodies in the air
stream.
Vibration causing
premature failure
of the tube
bundle.
•
Poor fitting of the
line tap onto the
pipe, or being
fitted to badly
formed or
flattened pipe
work.
•
Ensure the correct size of
tap valve is being used
and read the instructions
for its installation.
•
Fit a line tap to access a
system, and then braze a
Schrader connector to
replace it – do not leave
the line tap valve on the
system.
•
Leak test any line taps
found fitted and replace
them if possible.
•
Use of the wrong
size line tap
•
Loosening of the
line tap valve due
to movement and
vibration.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
•
page 22
9. Pressure switches
•
•
•
•
•
Vibration causing
the pressure
coupler to split or
damage to the
pressure switch.
The pressure
coupler chafing.
Rupture of the
switch bellows
due to vibration or
liquid hydraulic
action.
Failure of the
flare connection
onto the switch.
Poorly supported
or fixed switch
body.
•
•
•
•
•
•
•
10. O-rings
Use flexible pressure
couplers where possible
(stainless steel braided
type offer a high degree
of strength and
mechanical protection).
Make sure pressure
couplers do not rub or
chafe on other pipes or
vibrating surfaces.
Ensure the switch is
correctly supported /
fixed.
Use flare solder adaptors
on the switch where
copper pipe is being
used.
Use dual bellows
switches where possible.
Connect the switches to
minimise the transfer of
vibration into the switch.
Always leak test inside
switches (be aware of the
risk of electric shock).
•
Wear, hardening
or flattening,
especially when
subjected to
extremes of
temperature.
•
Check (for roundness
and flexibility) and
change seals rather than
re-using the existing
ones, especially during a
refrigerant retrofit.
•
Leakage after
retrofitting
because of a
different reaction
to the new oil.
•
Oil seals before fitting
them.
•
Ensure the replacement
seal is suitable for the
system oil and
refrigerant.
O-rings are widely used in components
such as sight glasses, solenoid valves
and shaft seals.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 23
11. Capillary tubes (pressure couplers
and expansion devices)
12. Return bends on evaporators and
condensers
•
Chafing due to
insecure fixing.
•
Leakage where a
capillary tube
expansion device
enters / exits the
suction line.
Likely cause
•
Corrosion due to
chemical action
on the return
bends on coolers
or air cooled
condensers.
Since the copper
used in these
heat exchangers
is thinner than
normal copper
pipe work, a
surface pinhole is
likely to result in a
leak in a relatively
short period of
time. Aggressive
environments
(such as a salty
or acidic
atmosphere)
accelerate
damage and
hence leakage.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
•
Check capillary tubes are
firmly located and cannot
chafe – correct if
necessary.
Solutions
• Leak test return bends
carefully, especially if the
atmosphere is
aggressive (e.g. in food
factories where salad is
washed in chlorinetreated water; where
vinegar products are
made; close to the sea).
• If evaporators and
condensers that are
prone to leaks from
return bends are to be
replaced, specify
materials which are less
susceptible to damage
such as coated or electro
plated heat fin blocks.
• When chemical cleaners
are used ensure they are
totally washed off.
page 24
13. Condensate tray pipe work
•
Corrosion of the
discharge line
because of contact
with air and water.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
•
Always leak test in
the vaporiser tray
and check the
condition of the pipe
work. If it is
corroded, replace
the pipe work before
it fails.
•
Where possible,
replace the pipe
work with a plastic
coated type as this
extends the life
dramatically.
page 25
Test you knowledge
Doing the following exercises will help to reinforce what you have read in this module.
Describe how refrigerant leakage impacts on climate change, both directly and indirectly.
List five common leak points that you have come across when you have been working on
RAC systems.
Calculate the impact of a 25kg leak of R134a in terms of passenger air miles.
Prepare a business case for an existing customer to persuade him to invest in a leakage
reduction measure.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 26
Appendix 1, GWP of refrigerants
GWP 2
Refrigerant
Type
Composition
R22
HCFC
R22
R401A
HCFC blend
R22 / R152a / R124
970
R401B
HCFC blend
R22 / R152a / R124
1060
R409A
HCFC blend
R22 / R142b / R124
1290
R413A
HCFC blend
R134a / R218 / R600a
1770
R402A
HCFC blend
R22 / R125 / R290
2250
R402B
HCFC blend
R22 / R125 / R290
1960
R403A
HCFC blend
R22 / R218 / R290
3570
R408A
HCFC blend
R22 / R143a / R125
2650
R134a
HFC
R134a
R23
HFC
R23
R404A
HFC blend
R143a / R125 / R134a
3260
R507A
HFC blend
R143a / R125
3300
R407A
HFC blend
R32 / R125 / R134a
1770
R407B
HFC blend
R32 / R125 / R134a
2280
R422A
HFC blend
R125 / R134a / R600a
2530
R407C
HFC blend
R32 / R125 / R134a
1525
R417A
HFC blend
R125 / R134a / R600
1950
R422D
HFC blend
R125 / R134a / R600a
2230
R410A
HFC blend
R32 / R125
1725
R290
HC
Propane
3
R1270
HC
Propylene (propene)
3
2
1500
1300 (1300)
11700 (12000)
GWP basis – time horizon 100 years, values according to EN378-1:2008
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 27
Appendix 2, F Gas and ODS Compliance Checklists
The table on this page can be used as a checklist when auditing compliance with F Gas and
ODS regulations.
Site name and
address
Contact name
System information
Audited by
Date
Compliance with F Gas Regulation 842/2006
Compliant?
Leak tests
Annually for systems
between 3 (6kg if the system
is hermetically sealed) and
30 kg charge.
Twice a year for systems
over 30 kg charge.
Fixed leak
detection
Required for systems over
300 kg charge. Records
should show this has been
checked annually.
Recovery
Required during service and
maintenance and at end of
life.
Records
Required for systems over 3
kg charge to record
refrigerant usage, leak tests.
Comments and recommended
actions
Qualifications Personnel who handle
refrigerant must hold the
appropriate qualification.
Labeling
Systems installed after
01.04.2008 must be correctly
labeled.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
page 28
Compliance with ODS Regulation 2037/2000
Compliant?
Phase out
Virgin HCFCs not to be used
to service systems after
31.12.2009.
Recycled HCFCs not to be
used after 31.12.2014.
Leak tests
Annual leak test required for
systems over 3 kg charge.
Recovery
Required during service and
maintenance and at end of
life.
Training
Personnel who handle
refrigerant must hold the
appropriate qualification.
REAL Zero Leak Reduction Training Module 1 © Institute of Refrigeration 2009
Environmental, cost and legal aspects of refrigerant leakage
Comments and recommended
actions
page 29
Refrigerant Emissions and Leakage ZERO Project
Reducing leakage through appropriate
maintenance and service
Training Modules
available:
TRAINING MODULE 2
1 - Environmental, cost
and legal aspects of
refrigerant leakage.
2 - Reducing leakage
through appropriate
maintenance and service.
3 - Minimising leakage in
new systems.
4 - Reducing leakage
through site specific
surveys and advice.
The Carbon Trust works with groups of organisations
to reduce carbon emissions and costs.
www.realzero.org.uk
Sponsored by
Module 2
Reducing Refrigerant Leakage through Appropriate Maintenance
and Service
Systems which are correctly serviced and maintained leak less refrigerant because they
work at less onerous conditions, transmit less vibration and have fewer potential leak points.
Poor servicing can introduce leakage, for example through uncapped valves. An
appropriate leak test regime as part of planned preventative maintenance will detect any
leakage early, thus reducing the associated environmental and financial costs.
For many systems reducing refrigerant leakage is a low priority, both during maintenance
and as a service call. Increasing the priority of leak reduction, and hence reducing leak
potential and finding leaks early has benefits:
•
•
•
•
Lower system running costs through maintenance of system efficiency;
Less downtime because leaks do not develop into critical faults;
Reduced service costs (including refrigerant) because leakage is detected earlier;
Lower environmental impact associated with refrigerant loss and increased energy use.
This benefits the end user and, where there is a comprehensive service and maintenance
contract, the contractor as well.
This section includes maintenance leak test regimes, indirect leakage assessment and hints
and tips on reducing leak potential when servicing systems. The information is practical –
following the guidance in this section when maintaining or servicing systems will help to
reduce refrigerant leakage.
In general, the top 5 service and maintenance actions which will reduce leakage are:
•
•
•
•
•
Cap valves
Where joints can’t be brazed, use flare solder adaptors or Lokring connections
Tighten flare nuts and bolts to the correct torque
Leak test systems thoroughly
Check electronic leak detectors are sensitive to the required accuracy
By the end of this module you will understand:
•
•
•
•
•
How regular leak detection can reduce leakage;
Available leak detection technology and how to get the best from the various leak testing
methods;
How to improve the effectiveness of leak detection;
Why leak testing and refrigerant charging should be logged and how to make best use of
the logs.
How to minimise the potential for leakage in existing systems through good service and
maintenance.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 2
And be able to:
•
•
•
Prepare a maintenance specification for a system to minimise leakage.
Use the F Gas logging calculator.
Determine the best leak detection methods for a particular system.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 3
2.1 System maintenance regimes for minimum leakage
Proactive maintenance is key to minimising refrigerant leakage:
•
•
An appropriate leak test regime identifies leaks early and hence reduces the financial
and environmental cost associated with refrigerant loss;
System maintenance ensures systems do not work at excessive pressures and
temperatures which increase the potential for leakage.
A fully comprehensive contract which includes the cost of refrigerant and associated labour
for leak repair provides the contractor with the greatest incentive for reducing leakage.
However, many systems under a fully comprehensive contract are not charged with
sufficient refrigerant, reducing the capacity and efficiency of the system. Appendix 1
provides more detailed information about different contract types and their effectiveness in
reducing leakage.
When tendering for maintenance, a contractor should have a leak reduction policy to
demonstrate how they effectively detect leaks and reduce leak potential on systems. The
policy should include:
•
•
•
•
•
Information demonstrating understanding of, and compliance with, the F Gas and ODS
regulations;
Leak detection equipment used;
Service and maintenance engineer training related to leak detection and leak reduction;
Leak detection as part of maintenance;
How leak potential is minimised during service and maintenance.
This is an important part of the contractor’s environmental policy.
Information for end users about appointing a contractor is provided in the Refrigeration
Efficiency Initiative Guide – Appointing and Managing Refrigeration Contractors, available to
download from www.ior.org.uk It is strongly recommended you read this document.
The maintenance schedule
Leak testing
The F Gas regulation (842/2006) specifies a minimum standard for leak testing:
HFC charge quantity
Leak test frequency 2
Under 3 kg (6 kg for hermetic systems)
Not required
3 to 30 kg (6 to 30 kg for hermetic systems)
1 per year
30 to 300 kg
2 per year
Over 300 kg
1
2
1
4 per year
Fixed leak detection must be fitted
Where fixed leak detection is fitted the leak test frequency is halved, although the
minimum requirement is 1 / year.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 4
Under the ozone depleting substance regulations (237/2000) systems with more than 3kg of
an HCFC must have an annual leak test.
The specification in both regulations should be considered a minimum standard – many
systems which are old and / or have many joints will require more frequent leak testing. The
actual leak test regime should be appropriate to age, condition, system type and leak
potential of the plant.
When leaks are found they should be repaired as soon as possible and re leak tested within
a month of the repair.
The F Gas regulation specifies that leak detection is carried out using an electronic leak
detector, a leak detection spray or a UV sensitive fluid. These are covered in more detail in
section 2.3.
Other maintenance activities
As well as leak testing there are other maintenance activities which will reduce the potential
for leakage. This includes anything which reduces head pressure and discharge
temperature such as:
•
•
•
•
•
•
Cleaning condensers;
Ensuring head pressure control is not set higher than necessary;
Checking condenser fans / pumps work;
Replacing suction line insulation if necessary;
Cleaning evaporators and checking they are defrosting correctly where necessary;
Checking evaporator superheat;
and anything which reduces vibration and vibration transmission such as checking:
•
•
•
•
Compressor and fan motor mountings;
Pipe support;
Effectiveness of vibration eliminators;
Pipes are not chafing.
A generic maintenance schedule is provided in Appendix 2.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 5
2.2 Records for effective refrigerant management.
Records of leak tests, leakage and refrigerant additions to systems provide essential
information which will help target proactive leak reduction. The template in Appendix 3 is
the basis of a log of information required under the F Gas regulation.
This template provides the minimum information required. It is important to accurately
specify leak location, including the component which is leaking if applicable. Information on
leak points can then be collated and used to target modifications on existing systems and
ensure components with an unacceptable leak rate are not specified in new installations.
F Gas Log spreadsheets
The Real Zero project has provided an F Gas Refrigerant Monitoring Tool (F Gas log) as an
Excel workbook, available from the website. It complies with the requirements of the F Gas
Regulations for recording refrigerant use data, with additional features and functionality.
It is recommended that one workbook is used for each individual site. The F Gas log has
worksheets for up to 10 individual systems into which the basic data about the system,
including entrained volume of refrigerant, and refrigerant additions and removals, leak tests,
follow up actions and fixed leak detection maintenance are added. The workbook is
designed to be simple to use and requires only basic Excel skills. Additional worksheets can
be added by advanced Excel users, for sites with more than 10 individual systems.
All common refrigerants are included in the workbook. Additional refrigerants can be added
by the user. The ‘Instructions for Use’ tab provides details of how to set up the refrigerant
monitoring tool, including the addition of new refrigerant data.
There is an F Gas log summary sheet which provides a management overview of the site’s
total refrigerant usage and the direct environmental impact of refrigerant leakage, in terms of
carbon equivalent and the leak rate as a percentage of the total charge, for the duration of
the log. This sheet is populated automatically, using the data from the individual system
worksheets.
The refrigerant usage information is also presented as bar graphs for each system in the
summary sheet and graphically in each system worksheet.
The spreadsheet includes a worksheet with useful web links, GWPs of common refrigerants,
and embedded Real Zero guides and F Gas Support documents (see ‘Information and
Guidance’ tab)
Example screen shots for a system worksheet and the F gas log summary worksheet are
shown on the following 2 pages.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 6
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 7
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 8
2.3 Direct leak testing methods.
Direct leak testing as part of routine maintenance, or to find a leak after refrigerant has been
lost, is an important part of reducing leakage. The F Gas regulation specifies that one of the
three methods outlined below should be used. The frequency is covered in section 2.1.
For practical reasons a combination of methods is often the most effective – for example a
sweep with an electronic leak detector followed up when necessary with leak detection fluid
to pinpoint leaks.
Method
Effectiveness
Compliance
Leak detection spray /
soapy water
Good for pinpointing leaks.
Allowed under the F Gas
regulation.
Electronic leak detector
Good for most leaks if the
detector is used and
maintained correctly (see
below). The detector
must be sensitive to the
refrigerant type.
Allowed under the F Gas
regulation – the leak
detector must have a
sensitivity of 5 g/year and
should be checked
annually.
Fluorescent additive
(injected into the system
with oil and detected using
an ultra violet lamp)
Can be an effective
maintenance tool for quick
leak testing. This is not
appropriate for some
systems – see below for
more information.
Allowed under the F Gas
regulation if approved by
the equipment
manufacturer – the use of
the additive voids warranty
on some compressors.
Leak detection spray / soapy water
Leak detection spray or soapy water is a sensitive leak detection method. The addition of
detergent to water and the constituents of the leak detection fluid ensure large bubbles form
easily with a very small pressure.
Soap and water solution can be made
by mixing liquid soap (washing up liquid)
with water into a thick consistency. It
should be left to stand until the bubbles
have dispersed, and then applied to
potential leak points with a soft brush. A
leak will cause bubbles to appear under
the soap solution. Soap and water is
ineffective on suction lines operation
below freezing. The low side of a
system must not be checked with fluid if
it is running on a vacuum. Leak
detection spray is also widely available
in aerosol cans or manual pump spray guns as shown in the photo.
This method is tedious to use on a system with many joints and inaccessible joints. It also
cannot be used on insulated pipe work.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 9
Getting the best from an electronic leak detector
Electronic leak detectors are test instruments which need to be looked after, checked and
maintained to ensure accuracy. Under the F Gas regulation they should be checked once a
year to ensure they are sensitive to a leak of 5 g / year. This is a minimum requirement –
for optimum reliability they should be checked more frequently, e.g. after 25 hours use.
Many older leak detectors are typically sensitive to 10 to 20 g / year. They will therefore
detect most leaks but do not meet the F Gas standard.
Where the leak detector has a filter (see
photo) it can become contaminated, for
example with oil. If this is the case it
must be replaced.
General guidance on using electronic
leak detectors is listed below, followed by information about specific types of leak detector.
•
•
•
•
•
The leak detector should be suitable for the refrigerant type and operating correctly;
The detector sensing tip should be moved slowly over the area being tested in a
constant motion;
If a leak is sensed the detector should be moved back and forth over the area until it is
pinpointed. The detector will zero out if it is simply pointed at a suspected leak and the
leak will be missed;
Refrigerants are heavier than air so a quick sweep of the cold room floor or cabinet base
is worthwhile - it often gives a quick indicator of leakage;
If an electronic leak detector has indicated a leak soapy water can then be used to
pinpoint the leak.
There are three types of leak detector in common use, using different methods of detection:
Corona discharge detectors pull air through an electrical field (corona discharge) around a
wire. The presence of refrigerant or other gases in the air changes the current in the wire
and triggers an alarm. The problem with this is it is not compound specific, so any substance
the leak detector senses could give false alarms including cleaning chemicals.
Heated diode leak detectors use a heated ceramic diode. The diode generates an
electrical current when it comes into contact with halogenated gas (HCFC and HFC
refrigerant) which the electronics convert into an alarm. The
heated diode sensor is affected by contamination, especially
from moisture or oil and will need replacement after
approximately 100 hours of operation. This type of detector is
much less likely to give false alarms. The more expensive
models have their own built in sensitivity check mode to
ensure the sensing head is actually working. They usually
calibrate out background levels of refrigerant. They have
high sensitivity to HFC refrigerants and are less prone to
false alarms from moisture and chemicals than corona discharge leak detectors. The photo
shows the heated diode sensor in a leak detector for HFCs.
Infrared (IR) detectors use an infrared absorption filtometer. This comprises a sampling
cell (see photo) with an infrared source at one end, an infrared energy detector at the other
end, and an optical filter in between them. The infrared source creates a high intensity
energy stream that passes through the optical filter blocking all wavelengths except those
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 10
that refrigerants absorb. The filtered infrared energy strikes the detector and causes it to
heat up. When refrigerant is drawn through the sampling cell by the internal pump, some of
the infrared energy is absorbed by the
refrigerant. This causes a decrease in
the amount of infrared energy reaching
the detector and a corresponding drop
in the detector’s temperature, which
triggers the alarm. The infrared
sensor needs changing less frequently
than a heated diode, typically every
800 hours.
Checking leak detectors
The F Gas regulation requires that electronic leak detectors are sensitive to a leak of
5 g / year and that they are checked annually. A reference leak should be used to check
the detectors are working correctly – just opening a cylinder or a connection on the system
to check a leak detector is not accurate enough and is illegal. Various reference leaks are
available to enable leak detectors to be checked - the detector needs servicing if it does not
detect the reference leak.
The photos below show a simple calibrated reference leak (courtesy of Vulkan Industries)
that fits onto the cylinder valve. When the valve is opened the flow through the device is 5 g
/ year. This type of device could also be fitted to a system and capped, and then used to
check the leak detector before checking the plant for leaks. More information is available on
the Real Zero website.
An alternative is a reference leak in a small bottle which leaks at a known
rate. The photo (courtesy of Javac) shows an example which contains
R134a and leaks at a rate of 5 g/year when the cap is removed.
Using fluorescent additives for leak detection
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 11
Fluorescent additives are used in other industries to find leaks, for example in car hydraulic
systems. They can be an effective and quick method of leak detection for RAC systems.
The fluorescent additive is charged into the system and is carried around the system with oil.
If there is a leak the additive leaks out with the oil and refrigerant, and stains the pipe work.
This stain is detected by an ultra violet lamp.
The amount of additive is determined from the oil charge in the system. If too little or too
much additive is used it will not be effective. Care has to be taken when charging the
system with additive – it can be messy. The additive must be allowed to circulate for a few
hours before it is effective.
This method has the advantage of highlighting the leak location even if the system has lost
its entire charge or is not currently leaking (some leaks are intermittent, such as those in
evaporators which leak only during defrost). After a leak has been repaired the additive
should be removed to prevent future misdiagnosis of leakage. A proprietary cleaner is
available.
This method can pinpoint leaks which cannot be easily identified by other methods, including
leakage from fin blocks as shown in the photo.
Some compressor manufacturers do not
give warranty on returned compressors if the
additive has been used in the system.
The additive circulates around the system
with oil. Coalescent oil separators are very
effective at separating oil and therefore the
additive does not circulate around the
system between the outlet of the separator
and the compressor suction.
Ultrasonic leak detectors
This method is not one of the methods specified under the
F Gas regulations, but it can be beneficial in some cases.
Ultrasonic detectors work on sound waves emitted when
gas escapes through a small orifice. This can be a leak of
refrigerant from a system under pressure or air being
drawn into a system under vacuum. The sound is well
above the frequencies sensitive to the human ear. The
electronics pick up these frequencies and amplify them into
an audible output. The technology isn’t new but has only
recently become cheap enough to use in hand held leak
detectors. The notable benefit of this type of detector is it
will detect any gas or vacuum leak including nitrogen and
HFC refrigerant.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 12
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 13
Leak test procedure
For effective leak testing sufficient time must be allowed to ensure the system is thoroughly
checked. The guidance below must be followed if all leaks are to be found.
;
The F Gas log (see section 2.2) should be reviewed to check where leaks have been
found previously.
;
The most appropriate leak test method should be selected, for example - a quick sweep
with an electronic leak detector followed by a leak detection fluid (soapy water) to
pinpoint the leaks.
;
;
;
;
The check should be methodical and not rushed.
;
The whole system should be accessible.
A visual check of the system should be made – e.g. oil stains and debris on pipe work.
The whole system should be checked, including
o
Fusible plugs and pressure relief valves and their vent lines;
o
Couplers (e.g. for pressure switches and gauges);
o
Inside pressure switches (as in
the photo) – beware live
electrical connections;
o
Service valve stem glands
(which must then be capped);
o
Schrader valves (which must be
tightened and then capped).
The O ring inside the cap
degrades when subject to high
temperatures. Hexagonal nuts
which can be tightened with a spanner are a better option.
If the suction pressure is low (e.g. below 1 bar g, 15 psig) it is beneficial to increase the
low side pressure to find leaks:
o
Simple condensing unit systems can be switched off but not pumped down;
o
Central plant should be switched off as a last resort.
;
;
The high side of the system should be checked at as high a pressure as possible.
;
All leaks found must be repaired and the connection re tested for leakage within a month
of the repair.
;
The first leak found is not always the only leak – the entire system MUST be
checked.
The air off air cooled condensers will disperse leaking refrigerant – if possible the fans
should be switched off whilst the affected parts of the system are checked. This also
has the advantage of raising the pressure, but extreme care should be taken not to over
pressurise the system.
It helps to know where leaks are likely to occur – the Real Zero Guide 13 Common Leak
Points highlights these.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 14
Pressure testing to find leaks
If a leak cannot be found with any of the methods above, the charge should be recovered
and the system pressurised with dry (oxygen free) nitrogen. A full procedure is available
from IoR (SES Good Practice Guide 24 – Pressurising installed systems with nitrogen to find
leaks). The important points to remember when carrying out a tightness test are:
•
•
•
•
•
•
A pressure of up to 10 bar g (150 psig) is usually sufficient to find leaks using a leak
detection fluid.
The regulator must be in good condition and not have an output pressure significantly
higher than needed (e.g. 10 bar g).
A manifold with a sight glass must not be used to pressure test. The photos below show
two options which will minimise the hazard of using a high pressure gas:
o a regulator, valve and braided steel hose assembly;
o a manifold without a sight glass (this is a manifold suitable for R410A).
The regulator should be closed (wound out, fully counter clockwise) when fitted it to the
nitrogen cylinder. The regulator should be opened slowly when all the connections to
the system are tight and the access valves are open. The cylinder pressure will be up to
230 bar (3450 psi) so the regulator should be opened slowly to prevent a sudden inrush
of pressure. The pressure should be increased in small increments, e.g. 1 bar, to the
test pressure.
The cylinder must be secure.
At the end of the test the nitrogen should be carefully vented to a well ventilated area or
outside.
A trace of hydrogen or helium with the nitrogen may
help leaks to be found at a lower pressure because of
the smaller molecule size. A suitable electronic
detector must be used – a standard refrigerant leak
detector is not sensitive to hydrogen or helium.
Nitrogen can be supplied with a trace of hydrogen (as
shown in the photo) or helium specifically for leak
testing.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 15
2.4 Indirect leak testing methods.
According to the F Gas regulation, “indirect” methods of leak detection can be used when:
•
•
•
Leaks are slow and difficult to detect;
The system is in a well ventilated area;
The method is accurate.
The chart below shows the progress of a leak against time and its impact on the system. In
the yellow segment the refrigerant buffer in the liquid receiver is leaking. In the green
segment there is insufficient refrigerant in the receiver to enable sub cooled liquid to flow
along the liquid line, leading to a reduction in capacity and efficiency. In the red segment
the capacity has dropped to below the load.
Ref lost
Intelligent
liquid level
monitor
Simple
liquid
level
alarm
Temperature
alarm
Liquid
line
bubble
detector
Atmos
monitor
load>capacity
If in right
place
performance
reduces
ref buffer
Time
The following methods can be used as indirect leak detection methods, but they often do not
provide a sufficiently early warning of leakage as indicated in the chart above. They can
also indicate other problems.
Insufficient cooling capacity ultimately resulting in a low temperature alarm
•
•
•
The buffer of refrigerant in the receiver will be lost before there is a reduction in cooling
capacity;
There is usually a further loss of refrigerant before the system’s capacity drops below the
load;
There is therefore potentially a significant loss of refrigerant before a high temperature
alarm occurs, the actual loss being dependent on load and ambient temperature.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 16
Operating conditions
•
•
•
The suction pressure will drop in some systems and this can be used as an indication of
refrigerant loss:
o On simple systems with a liquid receiver (e.g. condensing unit coupled to a
single evaporator), the suction pressure will drop when the buffer of
refrigerant has been lost;
o On simple systems without a liquid receiver the drop in suction pressure will
occur almost as soon as refrigerant is lost;
On central plant systems the compressors will run longer in the event of a loss of
refrigerant. This is not a reliable indication of refrigerant loss as the running time varies
significantly with load and ambient conditions.
The degree of sub cooling and useful superheat can be used as an indication of loss of
refrigerant. These are only useful if these conditions can be compared to those when
the system is working correctly and is fully charged. There is a simple procedure and
system log in Appendix 4 suitable for indirect leak checking.
Visual indication (such as oil stains)
•
Refrigerant leaks often result in oil stains or
debris on pipe work and these indicators should
not be ignored, but many joints are not visible
and this is not reliable for the whole system.
The photo shows a condenser with an obvious
refrigerant leak indicated by the oil stain on the right
hand corner of the fin block.
Bubbling in the liquid line sight glass
•
•
•
The buffer of refrigerant will be lost before bubbles appear in the sight glass so there can
be a significant loss of refrigerant before this shows;
Flash gas in the liquid line is dependent on load and
ambient, so bubbles may not always be present even
though the system is leaking and is short of refrigerant at
some conditions;
Bubbles can also indicate other problems such as a
blocked liquid line filter drier or loss of sub cooling at low
ambient temperatures.
Low liquid level alarm in receiver
•
•
•
The receiver liquid level varies with load and ambient temperature;
It is reliable when coupled with an “intelligent” monitoring system which can detect a
trend in liquid level;
The level sensor must be at the correct level and connected and working.
See section 2.5 for more information.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 17
2.5 Fixed leak detection systems.
Fixed leak detection systems are required to be used on systems with a charge of more than
300 kg of HFC according to the F Gas regulation. They are a benefit on many smaller
systems as well. The following are the main types of fixed leak detection system as defined
by the F Gas regulation:
•
•
Direct systems – use sensors to detect the presence of leaked refrigerant in areas
adjacent to refrigeration plant;
Indirect systems – measure system parameters to determine whether the refrigerant
charge is reducing.
These are outlined in more detail below, with information relating to service and
maintenance issues.
The F Gas regulation specifies that any fixed leak detection system should be checked once
a year.
The alarm system is important. If using a third party alarm system a dedicated channel
should be used for refrigerant alarms so the local or remote monitoring station identifies it
specifically as a refrigerant alarm and responds accordingly. Refrigerant leaks should be
treated as a priority. The alarm – local and remote – should be checked. There should be
an appropriate time delay, usually 10 to 45 minutes, on alarm activation.
Direct systems
The maintenance regime recommended by the supplier should be followed – this is often not
the case and as a result the system does not provide early warning of leakage. Problems
can occur with this type of system if the sensor tubes can draw in water, for example from
floor ducts. For more information about direct systems see Module 3, section 3.7.
Indirect systems
The most common indirect systems measure the level of liquid in the receiver. Examples
are shown below. It is difficult to check that these devices are operating correctly. The
most effective opportunity to do this is during commissioning – before the system is fully
charged the alarm point should be checked. The system should stop alarming as the
receiver fills during refrigerant charging.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 18
External systems are easier to maintain,
check or replace but have more potential leak
points. It should be ensured they are open to
the system and that any connecting valves are
not closed.
Optical sensor - internal to receiver – these are semi serviceable but have fewer
potential leak points.
The ultrasonic system is fully external – there are no connections to the system and
therefore no potential leak points. It can be retrofitted to horizontal receivers which
have sufficient ground clearance.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 19
2.6 How to reduce leak potential in existing systems.
Good service practice will reduce the leak potential of systems. This section outlines this for
general servicing, when making major repairs to systems and when retrofitting systems from
HCFCs. Refer to the Illustrated Guide to 13 common leak points as well as reading the
information below.
Leak potential is highest when:
•
•
•
•
•
Refrigerant temperature and pressure is highest;
Vibration is excessive;
Ice builds up excessively;
There is a wide and rapid temperature variation;
Systems are prone to external damage.
General good service practices to reduce leakage
The following lists the important points which will help to prevent leakage when servicing
systems.
Valve caps
Uncapped valves are a very common cause of leakage. Schrader valve
caps commonly leak because the rubber seal degrades when subjected to
heat (e.g. on a discharge line). A better cap is a hexagonal nut (blind flare
nut) which is tightened with a spanner.
Service valves
The packing gland between the valve body and
spindle shaft will leak with age and use. This can
also happen if the valve is overheated during
installation. If the valve stem leaks, the packing
gland should be tightened (see photo).
Rotalock valves are prone to leakage at the connection to the component. The following
photos show how the valve should be fitted. These are taken from a document about
replacing compressors – the full document1 is available from
www.emersonclimate.eu/documentation
1
Thanks to Emerson and Space Engineering Services for these photos and the associated text
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 20
1
Apply thread lock paste to the
component connections.
2
Refit the Rotalock valve, and
using the correct valve retaining
tool …
3
… tighten to the correct torque.
Ensure the valve position does
not stress the pipe work.
Replacing gaskets
When components sealed with gaskets (e.g. cylinder heads, flanges) are removed, for
example to replace a drier core, the gasket must be replaced. All of the old gasket must be
removed before applying the new one. The bolts should be tightened to the correct torque
(available from the component supplier) using the opposites rule – tighten one bolt then
tighten the one opposite it. Working in this way will evenly tighten the component.
Replacing brazed in components such as driers with flared components
The flare connections on the pipe work should preferably be made using flare solder
adaptors.
Flare solder adaptor for
expansion valve inlet
Flare solder adaptor for
other connections
If this is not possible the flare should be made using an eccentric flaring tool, see photos
below.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 21
The pipe should be de burred
The tube should be inserted to the correct
depth
The tool should be screwed in – the clutch
prevents over tightening and therefore over
stressing the pipe.
The resulting flare is less stressed at the
base of the flare and there is less thinning at
the flare face.
An alternative to a flared joint is Lokring connections. The photos below show how a good
joint is made using this connection system.
The Lokprep seals imperfections
in the pipe’s surface
The pipe must be inserted into
the fitting to the correct depth
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
The fitting is compressed, part 1
page 22
The fitting is compressed, part 2
The fitting is compressed, part 3
The completed joint
On some applications a pipe insert (as shown in the photo) might
be required to stabilise the pipe wall, especially with soft drawn
copper.
Joint preparation is essential to ensure a leak tight joint and close
adherence to the manufacturer’s instructions must be followed.
Using line tap valves
Line tap valves are commonly used to access
smaller systems which only have a process tube.
They provide an adequate seal for accessing the
system and recovering refrigerant, but not for
pressure testing, evacuation and charging.
They do not provide a good long term seal. The
correct size inserts should be used to ensure the
valve seals.
They must not be left on systems. The best
procedure is to fit a Schrader valve to the system
– for example if a compressor needs replacing
the Schrader valve can be brazed onto the process tube of the new compressor before it is
fitted.
Pressure relief valves
Most systems fitted with a pressure relief device use a
pressure relief valve and rupture disc combination, as
shown in the photo. The pressure relief device discharges
refrigerant if the pressure exceeds the set point (usually
the maximum system pressure, PS – see module 3 section
3.2 for more information). The rupture disc bursts at the set
pressure when the pressure relief valve discharges,
providing an indication that the valve has discharged.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 23
Pressure relief valves which have discharged excess pressure should be changed.
Pressure switches and connections
Some types of pressure switch and their connections to the system are common leak points:
•
•
Pressure switches with a single bellows arrangement often leak at the bellows;
Where the connection is a thermoplastic hose or flared copper they are prone to
leakage. Chafing is a major problem with this type of connection.
These components must always be checked when leak testing. If necessary replace
switches with sealed non adjustable types which are connected directly into the system (the
best option to minimise leak potential) or replace with a double bellows type connected to
the system using braided steel hoses.
Tightening torque
Many connections leak because bolts are not tightened to the correct torque. Component
manufacturers should be able to supply torques, for example a compressor manufacturer will
supply all the tightening torques for the bolts, plus and studs used in each compressor type.
Flare nuts should be tightened using a torque wrench specifically for flare nuts, as shown in
the photos below.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 24
Torque values are given in the table below.
Nominal pipe OD
(inch)
Tightening torque (Nm) for
manually produced flares
Tightening torque (Nm) for
flare solder adaptors
¼
14 to 18
20
5/16
33 to 42
n/a
3/8
33 to 42
30
½
50 to 62
60
5/8
63 to 77
100
¾
90 to 110
200
Vibration
Vibration is a common cause of pipe failure and hence leakage. Pipes should be correctly
supported to prevent stress. For example, the R404A in a 35m long, 1 3/8” OD would be
nearly 30 kg. If necessary additional pipe support should be added. See Module 3 for
more details about this.
Pipes should not chafe, for example against metal brackets or building structure. If
necessary protect with high density Armaload.
Pipe work vibration eliminators should be unstressed, e.g. not twisted.
Retrofitting to replace HCFCs
When HCFC refrigerants are replaced during a retrofit conversion, connections often leak as
a result. To prevent this it is recommended that:
•
•
•
The system is pressure tested for leak tightness after the HCFC charge has been
recovered. Any leaks found must be repaired and retested before charging with the new
refrigerant;
Seals should be replaced, for example in solenoid valves, globe valves and sight
glasses;
After charging with the new refrigerant the system should be leak tested.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 25
Test your knowledge
Doing the following exercises will help to reinforce what you have read in this module.
Source a reference leak and check your electronic leak detectors.
Use the F Gas logging calculator to summarise the refrigerant loss on a site you have data
for.
List five actions which would reduce leakage during service and maintenance of a site you
are familiar with.
Prepare a maintenance specification for a site you are familiar with, paying particular
attention to activities which will reduce leak potential and ensuring the leak test regime is in
compliance with the F Gas regulation as a minimum standard.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 26
Appendix 1, Maintenance and Service Contracts
Type of
contract
What’s included
Advantages
Disadvantages
Fully
comprehensive
All reactive service visits
and all planned
maintenance visits. All
parts and materials.
Note: this assumes
refrigerant is included,
although in some
comprehensive
contracts it is not
Appears the highest cost
option, but often the
most cost effective. It
does allow the end user
to budget for the year.
It is in the contractor’s
interest to minimise
leakage, especially if
refrigerant costs
increase.
Contractors do not
always fully charge
systems because of the
refrigerant cost. This
leads to systems with a
lower capacity and
efficiency.
The older the equipment
the higher the cost of
maintenance.
Labour &
Maintenance
(Semi
comprehensive)
All reactive service visits
and all planned
maintenance visits.
Excludes all parts. Note:
sometimes calls out of
hours are chargeable
A good option as the
contractor concentrates
on maintenance and will
make suggestions about
the plant knowing that
he does not have to pay
for part replacement out
of his budget.
The end user does not
have total control over
the budget.
Maintenance
Only
All planned maintenance
visits and materials.
Reactive service visits
and materials are
chargeable
A good option on new
plant where the
emphasis is on
maintenance.
Careful control needs to
be exercised on the
control of material
expenditure.
Pay As You Go
All chargeable
Careful management of
the contractor is required
and the user needs to
ensure there is a budget
for planned
maintenance.
This looks the cheapest
option, but will be the
worst for refrigerant
leakage – regular
maintenance is very
important.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 27
Appendix 2, Maintenance Schedule
The maintenance activities below will all help to reduce leak potential by minimising load and
hence plant operating time, and reducing high side pressures and temperatures. Leak
testing should be in accordance with the F Gas or ODS regulation with regard to frequency
and method (see sections 2.1, 2.2 and 2.3 for more information).
Refrigerant charge:
Check liquid level in receiver or check for bubbling in the
liquid line sight glass;
Check for visual indications of leakage such as oil stains;
Check for leaks all round the system and repair. Re leak
test the repair within 1 month. Frequency required under
the F Gas regulation is:
•
3 to 30 kg charge (6 to 30 kg if the system is
hermetically sealed), 1 / year
•
30 to 300 kg charge, 2 / year
•
300 kg + charge, 4 / year
•
The frequency halves if fixed leak detection is fitted, but
is never less than 1 / year.
Fixed leak detection
systems
Check these are working correct and that the local and
remote alarms are operational at the correct level.
Check valves are
capped
Fit caps to all valves;
Pipe work
Check pipes do not chafe;
Check caps on Schrader valves have good seals.
Check pipes are correctly supported;
Check vibration elimination is effective.
Condensers:
Clean condensers regularly, especially air cooled types.
The frequency of cleaning will depends on the condenser
location and its surrounding environment. An acid based
cleaner should not be used. High pressure water or
nitrogen or a foaming cleaner are effective and will not
damage the condenser;
Check fan / pump motors all work;
Check fans are not loose on motors.
Air coolers:
Clean them regularly;
Check the defrost (where necessary) is working correctly.
Badly frosted coils should be allowed to defrost naturally.
The use of heat or sharp implements will increase the risk
of leakage;
Check the defrost control allows the optimum time for
defrost;
Check fan / pump motors all work;
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 28
Check fans are not loose on motors.
Liquid chillers:
Check water pump operation.
Liquid line filter drier:
Check for blockage and replace if necessary.
Control:
Ensure the discharge pressure as low as possible – in
particular check that Head Pressure Control Settings are
not too high
Check that the suction pressure is as high as possible;
Check cold room / process temperature set points (they
should not be lower than required);
Check superheat setting of expansion valves and adjust if
necessary.
Insulation:
Replace suction line insulation if necessary;
Replace chilled liquid line insulation if necessary;
Repair or replace cold store insulation if necessary.
Cold store doors:
Ensure doors are not left open unnecessarily;
Repair or replace door seals if necessary;
Repair or replace strip curtains if necessary;
Repair or replace air curtain if necessary.
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 29
Appendix 3, F Gas Log
Under the F Gas regulation a log must be kept of refrigerant additions and removals from
systems and of leak tests and repairs. The example log below shows what information
must be included (Note: this is the minimum information necessary as suggested by DEFRA
F Gas Support - the Real Zero refrigerant monitoring tool, which can be downloaded from
the Real Zero website provides additional features and functionality – refer to Section 2.2 of
this document)
RECORD SHEET FOR F-GAS REGULATION
General Information
Plant Name
Reference No.
Location of plant
Plant Operator (Name, Address, Telephone)
Operator Contact
Cooling loads served
Refrigerant Type
Refrigerant Quantity (kg)
Plant manufacturer
Year of installation
Refrigerant Additions
Date
Technician/Company
Amount Added, kg
Reason for addition
Amount Removed, kg
Reason for removal. What was done
with recovered refrigerant
Refrigerant Removals
Date
Technician/Company
Leak Tests
Date
Technician/Company
Test Result (including location
and cause of any leaks identified)
Follow up actions required
Follow-up Actions
Date
Technician/Company
Related to test on
Actions Taken
Testing of Automatic Leak Detection System (if fitted)
Date
Technician/Company
Test Result
Comments
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 30
Appendix 4, Simple System Log for Indirect Leak Checking
Superheat is the temperature of a vapour above its saturation temperature or boiling point.
In a fully charged and correctly commissioned system the refrigerant exiting the evaporator
should be superheated by approximately 5K, i.e. it should be 5OC above the evaporating
temperature.
Sub cooling is the temperature of a liquid below its saturating temperature or condensing
point. In a fully charged system the refrigerant entering the expansion device should be sub
cooled, i.e. its temperature should be lower than the condensing temperature. The degree
of sub cooling depends on the length of the liquid line, where it is routed and the difference
between the condensing temperature and the temperature of the cooling medium (usually
ambient air).
Measuring Superheat
This is very simple, the
following tools are
needed:
•
•
•
A set of accurate
gauges
An accurate electronic
thermometer with a
suitable touch/contact
probe
A refrigerant
comparator
5°C
The steps below show
how superheat is
measured on a typical
system:
1. Fit gauges on the suction pipe as close
to the evaporator outlet as possible.
There is usually a connection.
2. Take the suction pressure and using
the comparator convert it into a
saturated temperature. Check you are
using the ‘gauge scale’ and NOT the
‘absolute’ scale. When measuring
superheats of blends make sure you
use the dew, saturated gas or vapour
scale.
3. Take the actual temperature using the
thermometer immediately adjacent to
the expansion device phial or sensing
probe.
4. Calculate the superheat:
= evaporator exit temperature –
saturated evaporating temperature
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 31
To measure sub cooling the same tools are needed. The procedure is as follows:
1. Connect a gauge to the high pressure side of the system;
2. Convert the discharge pressure to the saturated condensing temperature using a
comparator. Use the gauge pressure scale. For refrigerant blends using the bubble or
saturated liquid scale;
3. Measure the temperature of the refrigerant in the liquid line about 150 mm from the
expansion device using a probe thermometer;
4. Calculate the sub cooling:
= condensing temperature - liquid line temperature
The following table can be used to log the conditions.
Evaporator (useful) superheat
Suction pressure
Saturated
evaporating temp
Evaporator exit
temp
Superheat
TEV inlet temp
Sub cooling
Liquid line sub cooling
Discharge
pressure
Saturated
condensing temp
REAL Zero Leak Reduction Training Module 2
Reducing refrigerant leakage through appropriate maintenance and service
© Institute of Refrigeration 2009
page 32
Refrigerant Emissions and Leakage ZERO Project
Minimising leakage in new systems
Training Modules
available:
TRAINING MODULE 3
1 - Environmental, cost
and legal aspects of
refrigerant leakage.
2 - Reducing leakage
through appropriate
maintenance and service.
3 - Minimising leakage in
new systems.
4 - Reducing leakage
through site specific
surveys and advice.
The Carbon Trust works with groups of organisations
to reduce carbon emissions and costs.
Sponsored by
Module 3
Minimising Refrigerant Leakage in New Systems through Good
Design, Installation and Commissioning
This module shows how systems should be designed, installed and commissioned to
minimise leakage. It is not intended to be a complete system specification – it just covers
information related to refrigerant leakage reduction. It can be included in a full specification
for system design, installation and commissioning.
There is a range of useful information in various standards and codes, in particular:
•
•
EN378:2008 – Refrigerating systems and heat pumps – Safety and environmental
requirements. Parts 1 and 2 are the most relevant;
The Institute of Refrigeration’s Safety Code of Practice for Refrigerating Systems utilising
A1 Refrigerants.
It is strongly recommended you obtain and read these documents.
The key points of a specification to minimise leakage are:
•
•
•
To minimise the potential for leakage, for example by using a few connections as
possible and brazing them;
To minimise the quantity of refrigerant in the system;
To reduce the direct environmental effect of leakage by using low GWP refrigerants
where possible.
By the end of this module you will understand:
•
•
•
What aspects of system design effect refrigerant leak potential;
The importance of good installation practices to minimising leakage;
Why commissioning is a key part of the process.
And be able to:
•
•
•
•
•
Specify systems which have minimum leak potential;
Use standards to aid the design process;
Design pipe work with minimum leak potential;
Specify installation procedures which minimise leakage;
Specify commissioning procedures which minimise leakage.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 2
The process from system design to specifying maintenance is summarised in the following
listing. This is not a comprehensive map of the process, but it does include everything
relevant to reducing leak potential of new systems.
Activity
1
Ensure there is close project management to maintain standards and compliance
with regulations and the end user specification.
2
Allow sufficient time to carry out the design, installation and commissioning process
properly.
3
Follow the appropriate standards and regulations, in particular EN378:2008 and the
Pressure Equipment Directive.
4
Ensure pipe and components are selected with a view to leakage reduction.
5
Carry out a site survey to locate the best area for equipment location to minimise
pipe runs and provide good access.
6
Prepare detailed drawings to show pipe size (including thickness), support and
vibration elimination.
7
Ensure components such as pipe are properly stored to eliminate contamination and
damage.
8
Brazing – use qualified brazers and appropriate materials, and follow correct
procedures with regard to nitrogen purging and component installation.
9
Process the system properly (strength and leak tightness testing) to finds leaks early
and repair them with minimum disruption.
10
Evacuate the system thoroughly to remove contamination which can increase leak
potential.
11
Charge the correct amount of refrigerant.
12
Record the processing pressures and refrigerant charge.
13
Run test the system and commission it to minimise operation at excessive pressures.
14
Carry out a final leak test, especially on the processing access points.
15
Re visit the site after one month in operation to leak test and check system
operation.
16
Prepare a maintenance schedule which provides an appropriate leak test regime and
ensures the operating conditions remain at the optimum level.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 3
3.1 System Design Basics For Minimum Leakage
This section covers aspects of the overall system design which will impact on leakage.
Refrigerant type
The impact of refrigerants on climate change varies widely. Natural refrigerants have a very
low direct impact whereas most HFCs are several thousand times more damaging (see
Module 1, Appendix 1 for more information on GWPs). Natural refrigerants are often more
difficult to use, but in many cases this is offset by the improvement in environmental
performance. Leakage reduction is important whichever refrigerant is selected because a
leaking system will be less efficient. In addition, some of the natural refrigerants are more
hazardous than HFCs. The table below provides more detailed information about the
commonly used natural refrigerants.
Refrigerant1
GWP
Where currently
used
Important points
R717
(ammonia)
0
Industrial systems
Toxicity and flammability necessitate additional
safety requirements;
Cannot be used with copper components
(including hermetic and semi hermetic
compressor motors);
Performance and efficiency at least as good as
HFCs.
The skills and knowledge required exist in the
industrial sector.
Hydrocarbons 3
such as
R290, R1270
Small integral
systems, small
commercial
systems, liquid
chillers
Flammability limits refrigerant charge sizes;
Good thermodynamic properties;
Compatible with a range of compressor
lubricants;
Efficiency up to 20% higher than HFC
refrigerants.
Several thousand engineers have received
training in the safe handling of HCs.
R744
(carbon
dioxide)
A few retail central
plant and industrial
systems
Very high operating pressures;
Very high refrigerating effect;
New components required which are
becoming more widely available;
Very few engineers with knowledge and
experience – training is a significant issue;
A wide range of system designs both sub and
trans critical are in development, increasing
the training / skills issue.
1
The GWP of HFC refrigerants also varies widely, for example R134a and R407A both have
approximately half the GWP of R404A. For this reason both of these refrigerants are
1
The use of these refrigerants is covered in a series of Safety Codes from the Institute of
Refrigeration. See www.ior.org.uk for more information and to obtain these publications.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 4
increasingly used in place of R404A in order to reduce the direct impact on climate change
in the event of a leak.
When selecting a refrigerant energy efficiency must also be considered – do not
select a refrigerant on the basis of its GWP alone.
System capacity
The lower the capacity of a refrigeration system the lower its refrigerant charge needs to be.
To minimise the capacity:
•
Minimise the load, for example by:
o Using free cooling where possible
o Reducing auxiliary heat loads such as those from evaporator fan motors and
defrosting
o Minimising air change loads by improving door control on cold rooms and
using display cabinets fitted with doors.
•
Do not oversize the system:
o Avoid using unnecessary “safety factors” when calculating the load
o Be realistic about the maximum load.
•
Split the load into smaller components;
o Split a large system into several smaller ones – this has the advantage of
spreading the risk in the event of failure
o Avoid using one system for different temperature applications (“lowest
common denominator cooling”).
The options for reducing capacity also improve energy efficiency. For more information on
reducing system capacity see the Guide: Purchase of Efficient Refrigeration Plant from
www.ior.org.uk
Refrigerant charge reduction
There are a range of options to consider to reduce the refrigerant charge and they are listed
below.
System type – indirect vs. direct expansion
The amount of refrigerant is significantly lower in indirect systems such as liquid chillers,
especially where plant is very remote from the load. There are advantages and
disadvantages to indirect systems:
•
•
•
•
•
The system is more compact and therefore has a lower leak potential;
The refrigeration system pressure drops are lower;
The secondary fluid is at a low pressure and therefore less likely to leak than refrigerant
at high pressure;
The secondary fluid usually has a low environmental impact;
There is an additional heat transfer process which usually has the effect of reducing the
evaporating temperature and hence efficiency, although this may be offset by lower
pressure drops;
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 5
•
A secondary fluid pump is usually required, adding to the power consumption.
In many cases the energy penalties of the additional heat transfer process and the pump are
less than the benefit of lower pressure drops and reduced leakage of primary refrigerant.
Natural refrigerants such as HCs and ammonia are often more easily and safely used in
indirect systems.
Receiver type, size and orientation
If the system is designed to pump down, the receiver and the liquid line between the receiver
and the pump down solenoid valve must be large enough to contain the system’s refrigerant
charge. The receiver must never be more than 80% full of liquid.
If a pump down is not required the receiver size can be significantly reduced (in which case
the receiver is termed a “surge vessel”). In this case the receiver must be sized to contain
the buffer of refrigerant required – i.e. the difference between the charge required for
maximum load and that for minimum load. This will vary widely on systems which have
multiple evaporators which are independently controlled, but there will be less variation in
systems with a narrower capacity range, thus minimising the receiver size required.
Vertical liquid receivers require less refrigerant charge to ensure the receiver dip tube always
draws liquid refrigerant.
Plant location
To reduce the refrigerant charge in the liquid line the plant should be located close to the
load wherever possible. For example, a condensing unit system which has the plant 20 m
from the evaporator rather than 2 m will contain about 50% more refrigerant. In addition,
the potential leak points are greater because of the longer pipe length.
Pipe size
The liquid line pipe diameter has the greatest impact on the refrigerant charge amount.
Liquid line pipe sizing is a compromise between refrigerant charge amount and pressure
drop. If the liquid line pressure reduces, the degree of sub cooling relative to the saturated
condensing temperature also reduces. The pipe diameter should be as small as possible
whilst ensuring the pressure drop is not excessive enough to cause flash gas (loss of sub
cooling).
Minimising head pressure
The system should run at the lowest possible head (condensing) pressure to minimise leak
potential. At the design stage this is achieved by:
•
•
•
•
Using water or evaporative cooled condensers if possible;
Using a large condenser (although this usually also increases the refrigerant charge);
Ensuring air cooled condensers are located where air is not restricted, recirculated or
warmer than necessary;
Allowing head pressure to float with ambient as much as possible.
Reducing the head pressure also improves energy efficiency.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 6
Components
The use of certain components can increase the leak potential of a system. The following
list is generic and includes either alternatives with lower leak potential or methods of
reducing leakage.
Valves and other components subjected to high side pressure and especially discharge
temperature should be carefully selected.
Access points
Sufficient access should be provided to the system to allow it to
be processed and checked. Service and shut off valves have a
potential for leakage at the valve stem, gauge ports and
connection to the system. Schrader valves which are capped
have fewer potential leak points. Schrader valves should be
securely capped, preferably with a hexagonal nut which can be
tightened with a spanner (as shown in the photo). Schrader
valves should be specified / purchased with a hexagonal nut cap
rather than a knurled cap.
Where rotolok type valves are used, they should be tightened to
the correct torque and thread lock paste used on the component
connection point. Module 2 has more detailed information about
this.
Isolating valves
Isolating valves should be accessible and marked on the “as installed” drawing to ease
location and hence leak checking.
There should not be more valves than are actually required for serviceability. The
frequency of use of these valves should be carefully considered – there is a balance
between the number of valves needed for servicing vs. the leak potential of this type of
valve.
Globe valves typically have a number of seals and gaskets which can degrade and hence
are potential leak points. Ball valves are preferable because they have few potential leak
paths. They have the added benefit of having almost zero pressure drop.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 7
3.2 Key Pressures
The maximum operating pressure of a system is dependent on the maximum condensing
temperature, which in turn depends on the maximum temperature of the cooling medium –
usually related to ambient temperature. EN378-1:2008 specifies design temperatures from
which to calculate the maximum pressure (PS). The following is an extract relevant for most
UK ambient conditions:
High pressure side
Specified design temperature
Condenser type
O
32 C ambient
38OC ambient
55OC
59OC
Air cooled
Water cooled
8OC above the maximum leaving water temperature
43OC
Evaporative cooled
43OC
Low pressure side
Specified design temperature
Evaporator location
O
32 C ambient
38OC ambient
Subject to external
ambient
32OC
38OC
Subject to internal
ambient
27OC
33OC
In a well designed system the actual maximum operating pressure would usually be well
below PS.
The value of PS determines the pressures which pressure relief valves (PRVs) and pressure
switches should operate, and the pressure switch should be used for strength and tightness
testing:
Pressure relief device setting
1.0 x PS
Pressure relief valve should achieve full flow
1.1 x PS
High pressure switch setting for systems with pressure relief devices
0.9 x PS
High pressure switch setting for systems without pressure relief devices
1.0 x PS
2
Strength test
1.43 x PS
or
1.1 x PS
Tightness test
<=1.0 x PS
2
A factor of 1.43 is generally required for component testing. A factor of 1.1 is acceptable for field
installed pipe work. See EN378-2:2008, section 6.3.3 for full details.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 8
Example for an R404A system with an air cooled condenser and the evaporator in a retail
display cabinet or cold store:
High side:
PS = 24.8 bar g (pressure at 55OC).
• The PRV should be set at 24.8 bar g and should fully relieve at 27.3 bar g.
• The high pressure switch should be set at 22.3 bar g.
• The strength test pressure is 27.3 bar gauge for the pipe work.
• The tightness (leak) test pressure is 24.8 bar g.
Low side:
PS = 12.2 bar g (pressure at 27OC).
• The strength test pressure is 13.4 bar gauge for the pipe work.
• The tightness (leak) test pressure is 12.2 bar g.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 9
3.3 Pipe Design
The type of joints used to connect pipes and components and how pipe is supported are
fundamental to reducing the potential for leakage. Vibration can also lead to catastrophic
leakage so appropriate vibration elimination is essential.
Pipe
Copper pipe should comply with the standard EN12735. The thickness selected should be
sufficient for the maximum pressure (PS) of the pipe section. Appendix 1 provides a table
of maximum pressures for a range of pipe ODs and thicknesses. This information is usually
also provided by pipe sizing software.
Joints
A German study has shown that 96% of leaks are from field assembled joints3. To minimise
this leakage joints should be brazed wherever possible. See section 4.5 for information
about brazing standards and qualifications.
Mechanical joints are appropriate for some connections, for example for filter driers in
smaller systems which cannot easily be changed if they are brazed in and the inlet to
thermostatic expansion valves. In these cases flare solder adaptors should be used (see
photos which are of Danfoss components). These provide the ease of component change
of a flared connection, with the reliability of a brazed joint.
Flare solder adaptor for
expansion valve inlet
Flare solder adaptor for
other connections
The flare solder adaptor specifically for expansion valves has a flat face which seals to the
orifice assembly of the expansion valve. The standard flare solder adaptor has a copper
gasket which must be used to provide a reliable seal.
If flares must be produced manually it is strongly recommended that an eccentric flaring
block is used. This reduces the thinning of the material at the base of the flare, hence
reducing leak potential.
33
2005 Annual Institute of Refrigeration Conference
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 10
Manually made flares should be tightened to the correct torque. The table below provides
recommended torque values for flare nuts. The values for manually produced flares are
taken from EN378-2:2008, section 6.2.3.2.3. The values for flare solder adaptors are from
Danfoss.
Nominal pipe OD
(inch)
Tightening torque (Nm) for
manually produced flares
Tightening torque (Nm) for
flare solder adaptors
¼
14 to 18
20
5/16
33 to 42
n/a
3/8
33 to 42
30
½
50 to 62
60
5/8
63 to 77
100
¾
90 to 110
200
Over tightened flare nuts will be more susceptible to failure. Under tightened flare nuts will
leak immediately they are under pressure.
Pipe routing and support
To improve the ease and effectiveness of leak detection pipe should be routed to avoid joints
in inaccessible areas. The routing should also minimise pipe length to reduce potential leak
points. On installations with several systems, pipes should be labelled with the system
reference.
Pipe support is critical to minimising stress which can lead to failure. Spacing for pipe
support is provided in the following table4 for copper pipe:
Pipe outside diameter
Spacing
15 to 22 mm soft (5/8” to 7/8”)
2m
22 to <54 mm half hard (7/8” to 2 1/8”)
3m
54 to 67 mm half hard (2 1/8” to 2 5/8”)
4m
Pipe should not be in direct contact with metal supports or
hangers. High density Armaload (see photo) should be used
to prevent contact and hence rubbing and subsequent pipe
failure. The hanger size should be sufficient to accommodate
all pipes without any of them rubbing against the hanger.
Some of the hangers should be tethered to stop the refrigerant
pulsations shifting or swinging the hangers.
Where pipe passes through walls etc they should be sleeved.
Courtesy of Armacell
Enterprise GmbH
4
From EN378-2:2008, section 6.2.3.3.3.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 11
Vibration elimination
Vibration eliminators should be fitted to pipe work to and from flexibly mounted compressors,
as shown in the diagrams below (courtesy of Amnitec Ltd)
Vibration eliminators should also be used on pipe work to and from packs and condensing
units if they are mounted on anti vibration mounts.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 12
3.4 Over Pressure Protection
EN378:2008 sets a minimum standard for over pressure protection. You should refer to the
standard, in particular the flow charts in section 6.2.6 to determine the type of over pressure
devices which should be fitted. In summary, for most refrigeration systems using group A1
refrigerants (including HFCs):
•
•
•
Fusible plugs must not be fitted to systems with a charge greater than 2.5 kg;
Systems with a PED hazard category < 1 and a charge < 10 kg, a high pressure cut out
should be fitted;
Systems with a PED hazard category >= 1 or a charge >= 10 kg, a pressure relief valve
and a high pressure cut out should be fitted. A dual pressure relief valve is required if
the PED hazard category is 4, or if the receiver can be isolated.
This information is a general interpretation of EN378, refer to the standard for specific
details.
High pressure switch
The connection between a high pressure switch and the system is a potential point of
leakage, as is the bellows in an adjustable type switch. The use of solid state pressure
switches which are connected directly into the system reduce the potential for leakage from
both the switch and its connections.
Where adjustable pressure switches are used double bellow types have a lower leak
potential. They should be connected to the compressor or system using braided steel hose
as these will not degrade and leak. Care should be taken when routing the pressure
couplers to ensure they do not chafe. The switches should not be mounted directly onto a
compressor as the vibration will increase the probability of leakage and switch failure.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 13
3.5 Installation for Minimum Leakage
The quality of pipe work and connections has a major impact on the future leak potential of
systems.
Brazing
The following are the points key to brazing reliable connections:
•
•
•
•
•
•
•
•
•
The use of turbo torches should be avoided for brazing pipe work on RAC systems;
The oxy acetylene torch nozzle size should be appropriate for the pipe outside diameter.
An oversized nozzle is acceptable for small pipes, but an undersized nozzle on larger
pipes will not provide enough heat for good braze penetration;
The correct jointing materials should be used, e.g. in accordance with the user’s
specification with regard to silver content in copper phosphorous rod;
Surfaces should be clean and free of grease and oil;
Oxygen free nitrogen should be purged
through pipe work when brazing. The
photo illustrates the difference;
Copper should be annealed before
swaging (including softer coiled copper);
There should be access to the joint to
complete the joint in position;
A mirror should be used to check the
back side of joints;
Pipe should be cooled naturally and not
quenched immediately after brazing.
Brazer training and qualifications
Brazer training enables brazers to check the quality of their joints and hence improve the
standard of their brazing. The British Refrigeration Association and the CITB brazer
schemes are qualifications which include a practical test. The candidate brazes a test piece
comprising a number of joints of different sizes and orientations, copper to copper and
copper to a dissimilar metal. The joints are then cut open and examined for penetration.
Many brazers have not had the opportunity to examine their joints thoroughly – external
examination does not reveal the quality of the joint as illustrated by the photos below.
Brazers should regularly braze test joints and cut them open to check the degree of
penetration.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 14
Pipe Bends
Pipe should be bent rather than fittings such as elbows used. When bending pipe, the bend
radius should be at least 3 x pipe diameter. Pipe with the wall thicknesses shown in
Appendix 1 are suitable for bending providing the bend radius is no less than 3 x diameter.
Installing components such as valves and Schraders
Follow manufacturers’ installation instructions carefully when installing these components to
avoid damage which will increase leak potential. In particular:
•
•
Wrap a wet rag around valves such as ball valves and solenoid valves to prevent high
temperature at seals;
Strip globe valves to protect O rings;
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 15
•
Remove the core of a Schrader valve while brazing and replace it when the valve is
cooled using the correct tool.
Using valves with copper tails (see
photo) will reduce the heat that
reaches the valve itself. The
valve will still need to be wet
ragged.
Installing split air conditioning systems with flared connections
Most split air conditioning systems are supplied with flared connections. These are potential
points of leakage which can be avoided by:
•
•
Removing the flares on the indoor unit and directly brazing the connections;
Using flare solder adaptors on the pipe
work to the outdoor unit. The photo
shows flare solder adaptors prior to pipe
work connection.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 16
3.6 The Importance of Commissioning
Good commissioning is essential for the long term reliability and performance of a system.
This is when leaks should be identified and repaired, the system charged with the optimum
amount of refrigerant and controls correctly set.
Part of the commissioning procedure should be to check that all valves are securely capped
– many leaks occur at uncapped valves.
Pressure testing
All systems should be pressure tested for strength and leak tightness. Pressure testing on
site is hazardous. A risk assessment should be carried out and all non essential personal
removed from the vicinity while the system is strength tested.
The pressures for strength and leak tightness testing are
given in section 4.2. Oxygen free nitrogen is usually used
for these tests. An alternative is to use nitrogen with a
trace of helium or hydrogen (see photo). The small
molecule size of the helium or hydrogen and the special
detectors improves the leak detection rate.
In many systems it will be necessary to separate the high
and low pressure sides of the system – the low side should
not be subjected to a high side test pressure unless all the components are capable of
withstanding this pressure.
Pressure relief valves should be isolated during the pressure tests.
The strength test checks that joints are safe, but does not check for small leaks. The
strength test pressure should be held for a minimum of 15 minutes and the pressure reduced
to the tightness test pressure.
During the leak tightness test all accessible connections should be checked with a leak
detection fluid (soapy water). Where a helium or hydrogen trace has been used an
electronic leak detector sensitive to the helium or hydrogen should be used. It is unlikely
that all joints will be able to be tested directly. In this case the system should be left under
the test pressure for as long as possible (e.g. at least 24 hours) and any pressure change
monitored. The pressure of the nitrogen changes as ambient temperature changes. The
pressure will drop if the system is leaking, but this may be masked by the pressure changing
due to a temperature change. The table below gives the pressure change with ambient
temperature changes so this effect can be eliminated.
Temperature change, K
Pressure change, bar
5
0.7
10
1.4
15
2.0
20
2.7
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 17
If the pressure does drop because of leakage, the leak should be found, repaired and re
tested before charging.
When pressure testing large, multi evaporator systems, sections of pipe should be pressure
tested as they are installed.
Under the Pressure Equipment Directive independent verification of the strength pressure
test is required for many systems.
Pressure testing split air conditioning systems
Split air conditioning systems are often supplied pre charged. If the pipe work on these
systems is tested to the pressure specified in EN378, it is possible that the high pressure
nitrogen will leak past the outdoor unit connections and contaminate the refrigerant. To
prevent this, the test pressure should not exceed the pressure of the refrigerant in the
outdoor unit (which will be dependent on its temperature). For example, a pre charged
R410A outdoor unit will have a refrigerant pressure of 10 bar g at an ambient temperature of
10OC. The nitrogen pressure should not exceed 9.5 bar g.
Note – the test pressures will be below those specified in EN378, but this avoids the system
operating at excessive pressure due to nitrogen contamination – a condition which will
increase both power consumption and leak potential.
Evacuation
Systems should be evacuated to remove non condensable gases and moisture which, if left
in the system, increase the head pressure and hence increase leak potential. For effective
evacuation:
•
•
•
•
•
•
The vacuum pump should be two stage and as large as possible, and be charged with
clean oil;
The vacuum pump should be connected to both sides of the system. On large systems
it is beneficial to use two or more vacuum pumps connected to different parts of the
system;
The vacuum pump should be connected directly into the system, ideally using 3/8”
copper tube. The use of hoses and manifold sets should be avoided as they add a
restriction and often leak under negative pressure;
The vacuum should be measured at a point on the system as far as possible from the
pump connections, e.g. the furthest evaporator from the plant where there is often a
Schrader connection;
The vacuum should be measured using a vacuum gauge (not the manifold compound
gauge) and connected to the system at the furthest point from the vacuum pump, e.g. at
the furthest evaporator’s Schrader connection. Ensure the gauge is isolated before
pressurising the system;
Ensure there are no isolated sections of the system,
e.g. including compressors which often have integral
non return valves. A magnet should be used to open
solenoid valves as shown in the photo.
The system should be evacuated until a vacuum of 500
microns has been reached for new systems, 1000
microns for existing systems. See table for units of
measure used for vacuum. The warmer the system the
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 18
quicker and more effective the evacuation process will be. A triple evacuation process,
using oxygen free nitrogen to break the vacuum, is a more effective evacuation process than
a single deep evacuation.
in.Hg
Vacuum
0.00
Atmospheric
pressure
29.84
29.88
29.90
29.91
29.92
A perfect
vacuum
Microns
mm Hg
mbar
Torr
760,000
760
1013
760
2000
1000
500
200
2.00
1.00
0.50
0.20
2.7
1.33
0.67
0.26
2
1
0.5
0.2
0
0
0
0
Controls
Controls should be set to minimise operating time and head pressure. Setting controls to
achieve the best energy efficiency will also usually ensure systems are operating at
conditions which minimise leak potential:
•
•
•
•
Condensing pressure should be as low as possible;
Evaporating pressure should be as high as possible;
Useful superheat should be approximately 5K;
Pressure switch and electronic control differentials should be wide enough to prevent
short cycling.
More information is available in the energy efficiency guides on the IoR website
www.ior.org.uk
Post commissioning checks
The system should be run tested to ensure it is operating at the required conditions. When
the processing equipment has been removed the access points should be leak tested. The
system should be re checked (especially valves and any part of the system exposed to heat,
vibration and temperature change) after one month of operation.
Labeling systems
Systems should be labeled to show:
•
•
The text “Contains fluorinated greenhouse gases covered by the Kyoto Protocol”;
The abbreviated chemical names for the fluorinated greenhouse gases contained or
designed to be contained in the equipment using accepted industry nomenclature
standard to the equipment or substance (e.g. R404A);
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 19
•
•
The quantity of the fluorinated greenhouse gases, expressed in kilograms;
The text ‘hermetically sealed’ where applicable.
That the label may be placed in any of the following positions:
•
•
•
adjacent to the service points for charging or recovering the F gas,
on that part of the product or equipment which contains the F gas,
on, or adjacent to existing nameplates or product information labels.
The photos show an example of the correct label, and a roll of labels.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 20
3.7 Fixed Leak Detection
Loss of refrigerant will have an impact on the operating conditions of a refrigeration or air
conditioning system. The actual effect will vary with system type as shown below:
System type
Impact of leakage on operating conditions
System with no liquid
receiver
Drop in suction pressure
Drop in discharge pressure
Almost immediate loss of capacity
Simple condensing unit
with receiver / evaporator
system
Drop in suction pressure
Drop in discharge pressure
Loss of capacity when the “buffer” of refrigerant in the receiver
has been lost (the timing of this will vary dependent on the load
and ambient temperature)
Central plant multi
compressor multi
evaporator system
Increase in running time
Loss of capacity when the “buffer” of refrigerant in the receiver
has been lost (the timing of this will vary dependent on the load
and ambient temperature)
The diagram below gives a view of the effectiveness of various methods of leak detection5.
The graph shows the development of a leak:
•
•
•
5
Yellow area – leak has not yet had any impact on performance;
Green area – the leak is reducing capacity but not to a critical level;
Red area – the leak has reduced capacity to below the load with the effect that the
temperature of the cooled space / product is not being maintained.
Institute of Refrigeration, Presidential Address, October 2007
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 21
Simple
liquid
level
alarm
Ref lost
Intelligent
liquid level
monitor
Temperature
alarm
Liquid
line
bubble
detector
Atmos
monitor
load>capacity
If in right
place
performance
reduces
ref buffer
Time
Routine leak testing
maybe
The table below brings together the various methods of identifying loss of refrigerant,
highlights issues and provides an “effectiveness rating” of each method. Effectiveness
takes into account how early and accurately a leak is found by each method.
Method
Issues
Effectiveness
rating (10 =
best)
Atmosphere
monitor
(refrigerant gas
detector)
Usually only located in plant room – about 50% of
leakage occurs outside this area;
Often not correctly maintained.
5 if in plant
room only
10 if
throughout
plant (unlikely)
Intelligent
liquid level
monitor
Monitors liquid quantity in receiver and detects
trends which indicate loss of refrigerant;
Not widely available / used;
Methods of measuring liquid level / amount of
refrigerant in receiver are often unreliable.
9
Simple liquid
level alarm
Currently used, but often give false alarms,
especially where head pressure floats
significantly, therefore often disconnected or
placed at too low a level on the receiver;
Methods of measuring liquid level / amount of
refrigerant in receiver include ultra sonic, optical
and mechanical.
7
Ultrasonic liquid
line sensor
Uses ultrasound technology to detect bubbles in
liquid line – proven, reliable method;
Funding provided for development of system, but
none produced commercially yet;
5
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 22
Provides warning of other problems which result
in loss of sub cooling.
High
temperature
alarm
At times of low load / low ambient a significant
amount of refrigerant will be lost before the
system capacity drops to a level where
temperature cannot be maintained.
3
Routine manual
leak testing
Leaks test are carried out infrequently and rarely
find leaks early;
Some leaks are intermittent and may not be
present during the testing;
Many joints are inaccessible and / or insulated;
Leak testing is monotonous and therefore rarely
carried out conscientiously;
Service contracts are often not profitable so time
spent on leak testing is minimised;
Electronic leak testers might not be correctly
calibrated and maintained – soapy water is more
reliable but more difficult and time consuming to
use, and impossible on many commercial
installations;
Leak test technicians are not appropriately trained
(e.g. many technicians stop at the first leak found
and therefore miss leaks).
1, based on
typical
frequency
Routine manual
leak testing
using
fluorescent
additive
Simpler and quicker to use than electronic leak
testers and soapy water – it should therefore be
able to be used more frequently and effectively;
Identifies intermittent leaks;
Can highlight point of leakage even if all the
refrigerant has been lost;
Coalescent oil separators (used increasingly on
large commercial systems) remove all the oil and
additive from the discharge gas, therefore most of
the system does not contain the additive.
2, based on
typical
frequency
Under the F Gas regulation fixed leak detection must be used on systems with a charge of
more than 300 kg. Where it is used the frequency of routine leak testing is halved.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 23
Test your knowledge
Doing the following exercises will help to reinforce what you have read in this module.
Work out test pressures and settings for pressure relief valves and high pressure cut outs
for a system running on R410A in an ambient of 38OC.
List five key points to observe during installation of a split air conditioning system to
minimise leak potential.
Consider whether natural refrigerants could be used in systems you are familiar with.
Prepare a system design and installation specification with the primary aim of minimising
leak potential for a system type you primarily work with.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 24
Appendix 1, Maximum Pressure vs. Wall Thickness for Copper Pipe
The maximum pressures listed in the table below is based on BS1306:1975 (Copper and
copper alloy pressure piping systems) section 7.1, which provides the following formula to
calculate the minimum wall thickness of straight copper tube:
t = pd / [p + 20f]
re arranged as:
p = 20ft / [d-t]
Where:
t = minimum thickness, mm
p = allowable pressure, bar g
d = outside diameter of straight tube, mm (i.e. the maximum OD)
f = design stress, N/mm2 (based on an appropriate stress value (annealed) to reflect
the heating during fabrication).
f = 41 N/mm2 for copper tube joined by brazing and operating at temperatures up to
50°C
f = 40 N/mm2 for copper tube joined by brazing and operating at temperatures up to
100°C
f = 34 N/mm2 for copper tube joined by brazing and operating at temperatures up to
150°C.
Note – the temperatures for the f values above are maximum refrigerant temperatures, not
saturated refrigerant temperatures.
The table shows the maximum pressures for a range of pipe sizes calculated using the
formula above, with a tolerance of 15% on the pipe thickness.
Pipe,
Pipe,
Pipe SWG 1
Pipe
outside
outside
minimum
diameter, diameter, d,
wall
d, inches
mm
thickness, t,
mm 1
0.25
6.35
16
1.386
0.25
6.35
18
1.037
0.25
6.35
19
0.867
0.25
6.35
20
0.7769
0.25
6.35
21
0.6911
0.25
6.35
22
0.6044
0.325
8.255
19
0.867
0.325
8.255
20
0.7769
0.325
8.255
21
0.6911
0.5
12.7
19
0.867
0.5
12.7
20
0.7769
0.625
15.875
16
1.386
0.625
15.875
18
1.037
0.625
15.875
19
0.867
0.625
15.875
20
0.7769
0.75
19.05
18
1.037
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
Maximum Maximum Maximum
pressure, pressure, p, pressure, p,
bar g at
bar g at
p, bar g at
50°C max 100°C max 150°C max
temp
temp
temp
229.0
223.4
189.9
160.0
156.1
132.7
129.7
126.5
107.5
114.3
111.5
94.8
100.1
97.7
83.0
86.3
84.2
71.5
96.2
93.9
79.8
85.2
83.1
70.6
74.9
73.1
62.1
60.1
58.6
49.8
53.4
52.1
44.3
78.4
76.5
65.0
57.3
55.9
47.5
47.4
46.2
39.3
42.2
41.2
35.0
47.2
46.1
39.1
page 25
0.75
0.75
0.875
0.875
0.875
0.875
1.125
1.125
1.125
1.125
1.375
1.375
1.625
1.625
2.125
2.125
2.125
2.625
2.625
2.625
2.625
3.125
3.125
3.125
3.125
3.125
3.625
3.625
3.625
3.625
3.625
4.125
4.125
4.125
4.125
4.125
19.05
19.05
22.225
22.225
22.225
22.225
28.575
28.575
28.575
28.575
34.925
34.925
41.275
41.275
53.975
53.975
53.975
66.675
66.675
66.675
66.675
79.375
79.375
79.375
79.375
79.375
92.075
92.075
92.075
92.075
92.075
104.775
104.775
104.775
104.775
104.775
19
20
16
18
19
20
16
18
19
20
16
18
16
18
14
16
18
12
14
16
18
10
12
14
16
18
10
12
14
16
18
10
12
14
16
18
0.867
0.7769
1.386
1.037
0.867
0.7769
1.386
1.037
0.867
0.7769
1.386
1.037
1.386
1.037
1.726
1.386
1.037
2.244
1.726
1.386
1.037
2.7625
2.244
1.726
1.386
1.037
2.7625
2.244
1.726
1.386
1.037
2.7625
2.244
1.726
1.386
1.037
39.1
34.9
54.5
40.1
33.3
29.7
41.8
30.9
25.7
22.9
33.9
25.1
28.5
21.1
27.1
21.6
16.1
28.6
21.8
17.4
13.0
29.6
23.9
18.2
14.6
10.9
25.4
20.5
15.7
12.5
9.3
22.2
17.9
13.7
11.0
8.2
38.1
34.0
53.2
39.2
32.5
29.0
40.8
30.1
25.0
22.4
33.1
24.5
27.8
20.6
26.4
21.1
15.7
27.9
21.3
17.0
12.6
28.8
23.3
17.8
14.2
10.6
24.7
20.0
15.3
12.2
9.1
21.7
17.5
13.4
10.7
8.0
32.4
28.9
45.2
33.3
27.6
24.6
34.7
25.6
21.3
19.0
28.1
20.8
23.6
17.5
22.5
17.9
13.3
23.7
18.1
14.4
10.7
24.5
19.8
15.1
12.1
9.0
21.0
17.0
13.0
10.4
7.7
18.4
14.9
11.4
9.1
6.8
Note 1:
SWG 10 = nominal 3.25 mm, minimum wall thickness 2.76 mm
SWG 12 = nominal 2.64 mm, minimum wall thickness 2.244 mm
SWG 14 = nominal 2.03 mm, minimum wall thickness 1.726 mm
SWG 16 = nominal 1.63 mm, minimum wall thickness 1.386 mm
SWG 18 = nominal 1.22 mm, minimum wall thickness 1.037 mm
SWG 19 = nominal 1.02 mm, minimum wall thickness 0.867 mm
SWG 20 = nominal 0.914 mm, minimum wall thickness 0.777 mm
SWG 21 = nominal 0.813 mm, minimum wall thickness 0.691 mm
SWG 22 = nominal 0.711 mm, minimum wall thickness 0.604 mm.
REAL Zero Leak Reduction Training Module 3
Minimising leakage in new systems
© Institute of Refrigeration 2009
page 26
Refrigerant Emissions and Leakage ZERO Project
Reducing leakage through
site surveys and advice
Training Modules
available:
TRAINING MODULE 4
1 - Environmental, cost
and legal aspects of
refrigerant leakage.
2 - Reducing leakage
through appropriate
maintenance and service.
3 - Minimising leakage in
new systems.
4 - Reducing leakage
through site specific
surveys and advice.
The Carbon Trust works with groups of organisations
to reduce carbon emissions and costs.
Sponsored by
Module 4
Reducing Refrigerant Leakage through Site Specific Surveys and
Advice
This training module shows how to develop an effective strategy to reduce refrigerant
leakage from existing systems. It provides template survey forms, explanatory information
for end users and a template report. Details are provided showing how you can calculate
key information.
An important part of this process is feeding back information on potential savings to the
Carbon Trust via the Institute of Refrigeration. This information enables the Carbon Trust to
determine the effect of the Real Zero project and to gather further information about current
leak rates and the potential for reduction.
A typical site survey procedure is listed below:
1. Identify potential sites for survey, e.g. with existing customers or end users you have
identified who would benefit from this service. If your name appears on the IOR Real
Zero website you might be contacted by potential customers;
2. Outline to the customer the process and potential outcome (a template letter will be
made available when you join the REAL Zero website listing);
3. Assemble information about the site, including the F Gas records;
4. Carry out the survey (a template survey sheet is provided);
5. Consider how leakage can be reduced on the site (Real Zero guides and the information
in these training modules will help);
6. Prepare a strategy to the customer to reduce leakage (a template report is provided);
7. Report potential savings to the Institute of Refrigeration.
By the end of this module you will understand:
•
The range of information required to develop an effective leak reduction strategy.
and be able to:
•
•
•
Survey a range of RAC equipment to gather information about current leakage;
Develop a practical and effective strategy to reduce future leakage;
Provide a comprehensive report to end users which includes a business case for
reducing leakage.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 2
4.1 Site surveys to identify a leakage reduction strategy
The aim of the site survey is to gather information about the RAC equipment:
•
•
•
•
Its age and condition;
Its level of maintenance;
Current leakage and leakage potential;
Historical leakage points.
This information, coupled with generic information provided in the Real Zero guides, will
enable you to develop a strategy to reduce leakage from the systems surveyed.
These surveys are particularly beneficial on systems which often have a high leak rate
including:
•
•
•
Central plant such as is used in most supermarkets;
Other distributed systems where the evaporator is remote from the condensing unit (e.g.
many cold stores and food processing applications);
Split air conditioning systems (including VRV and VRF systems).
Equipment which is predominantly integral (“plug in”) will not generally have a high leak
potential so it is not usually worthwhile including them in this process. Many close coupled
systems such as chillers also generally have a low leak rate.
Explaining the process to end users
It is important that end users understand the benefits of the survey and how it will help them
reduce costs and the impact on the environment of the RAC equipment. The letter:
•
•
•
•
•
Introduces Real Zero;
Highlights the importance of leakage reduction;
Explains the process and the access to the RAC equipment and information that will be
required;
Outlines the potential benefits and how these will be reported;
Explains how and why information will be reported back to the IOR and the Carbon
Trust.
The template letter can be adapted to your own requirements, but it is recommended that
the information and wording are not changed significantly. The template letter will be made
available when you join the REAL Zero website listing.
Site survey
The survey is a visual check of the system plus a leak check. This survey will form the
basis of your customers Site Report and Leakage Reduction Strategy (see section 4.4).
It will typically take up to four hours to survey one central plant system. The survey record
sheet (an Excel spreadsheet) is available in YOUR REAL Zero TOOLKIT. It is important that
you do not change the format of this spreadsheet.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 3
1. The survey template is self explanatory. Most of the information will be available from:
•
•
•
•
The visual check of the system, which will include an indirect assessment of the level of
refrigerant charge. Training module 2 section 4 gives more information about this;
The F gas records;
General questioning of site staff regarding the level of reliability and historical problems
with the site;
A leak check using an electronic leak detector.
2. You may need to estimate the refrigerant charge if this is not available – this is covered in
the next section.
3. The survey includes a leak test of the system. This is not intended to be a full leak test
unless required by the end user. However, it should be possible to check most joints. You
should:
•
•
•
Use a handheld electronic leak detector, either an infra red or heated diode type;
Check it against a reference leak to ensure it is accurate;
Leak test as many joints as you can easily access, including common leak points such
as pressure switches and pressure relief valve vent lines.
This is covered in more detail in training module 2 which provides detailed information about
direct leak testing methods.
4. Filling in the site survey form. You can either print out the survey template to fill out
manually on site, transferring the data to the spreadsheet at a later date; or complete the
spreadsheet electronically during the survey.
5. When you have completed the electronic version of the survey save it in the following
format:
Your initials, end user name, site name, date.
For example:
AAA, End User Name, Town, 18.11.07.xls
A copy of this will have to be provided to the IOR so that the information on leak reduction
opportunities identified can be included in the IOR’s annual report for the Carbon Trust. The
information will not be used for any other purpose or divulged to any other party. See
Section 4.5
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 4
4.2 The correct refrigerant change amount
It is useful to relate refrigerant leakage to the refrigerant charge size (also called entrained
volume) to provide a leak rate as an annual loss percentage. For example a leak of 20 kg a
year in a system with an ideal charge of 40 kg is a 50% annual refrigerant loss. This allows
systems to be bench marked and comparisons made to average leak rates so problem
systems can be highlighted and targeted.
The correct charge amount is the minimum charge required for the system to run with
sub cooled liquid at the entry to all expansion devices throughout the entire range of
load and ambient conditions.
Many systems contain more refrigerant than required – the excess refrigerant is held in the
high pressure liquid receiver. In the event of a leak the excess refrigerant is lost before the
leak results in insufficient liquid in the liquid line (e.g. seen as flashing in the liquid line sight
glass) and the performance drops. The system is not technically over charged because it
does not result in liquid backing up in the condenser with a subsequent increase in
condensing pressure. But the excess refrigerant is not required and increases the potential
direct environmental impact in the event of a leak.
Some systems are undercharged because they were not charged with the correct amount of
refrigerant during commissioning or service. This is often the case when systems are
charged to a full liquid line sight glass when the system is not fully loaded. The system
appears adequately charged at low load, but when the load increases, demanding more
liquid refrigerant, it is not available.
Systems fitted with high pressure liquid receivers have a significant margin between being
undercharged and overcharged.
Calculating the correct charge size
The correct charge can be calculated from:
•
The quantity of refrigerant held in each evaporator and condenser (usually available from
the manufacturer in kg, or as a volume, litres);
•
The volume of the liquid line, condensate line (between condenser outlet and receiver
inlet) and any other pipe work which contains liquid refrigerant;
•
The capacity or volume of the liquid receiver at 25% full and other vessels which will
contain liquid refrigerant.
It is not usually necessary to consider the volume of pipe work and vessels which contain
only refrigerant gas as this will be a very small proportion of the total charge.
Appendix 1 gives example calculations and provides information about refrigerant density
required when calculating refrigerant weight from the volume of vessels and pipe work.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 5
Alternatively there is a refrigerant calculator and guidance note on calculating refrigerant
charge available from DEFRA F Gas Support which provides an approximate charge size
from simple information about the system which you can download at
http://www.defra.gov.uk/environment/air-atmos/fgas/pdf/refrigerantcalculator-v1-4.xls
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 6
4.3 Preparing a strategy for leakage reduction.
The following list of topics are those which you could potentially include in your strategy.
Not all of these will be relevant to every system, and there may be other equipment specific
information which you can add.
•
Background to the strategy with key points from the survey:
o Current and historical leakage
o Current standard of service and maintenance and its impact – positive and
negative – on leakage
o Age and condition of equipment;
o Compliance with the F Gas regulation.
•
Recommendations for improved service and maintenance, including:
o Modifications to the current maintenance scheme or a new maintenance
regime where necessary;
o A complete service if necessary, for example to carry out a thorough leak test,
cap valves, replace minor components and joints.
•
Recommendations for re work or replacement of components or systems, possibly
including:
o Pipe work improvements;
o Joint changes, e.g. from flares to brazed joints;
o Components changes, e.g. rotolok valves;
o System replacement;
o Improved access.
•
Issues related to HCFC replacement:
o Replacement of seals or gaskets which often leak more with the replacement
oil and refrigerant.
You will need to use the following information to develop a practical strategy:
•
•
•
•
•
Historical and current leakage information;
Current level of service and maintenance;
Compliance with F Gas regulation;
Type, age and condition of equipment;
Potential for leakage.
These are covered in more detail in the sections below, with general recommendations for
improvement from which site specific advice can be produced.
Historical and current leakage information
This comprises information from the F gas log and your own leak checking during the
survey. From this information you should be able to determine:
•
•
•
•
Annual leak rate as a percentage of system charge;
Leakage points, and in particular problem areas where leaks have recurred;
Reason for leaks – external damage, catastrophic failure or gradual loss of refrigerant;
Whether leak testing has been carried out in accordance with the F Gas regulation (see
module 1 about F Gas compliance and auditing).
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 7
If the end users existing F Gas log is inadequate it is recommended that you transfer the
information available to a REAL Zero refrigerant monitoring spreadsheet and encourage the
end user and their service and maintenance personnel to use this for recording purposes in
future.
The table in the module guide shows typical leak rates for different types of system.
Compare this with the systems you have surveyed to find whether they are better or worse
than average. Whatever the leak rate – there is always potential for improvement!
Reasons for leakage vary.
Where leaks have been caused by damage from an external source, e.g. a fork lift truck, you
need to identify vulnerable areas and recommend protection.
Catastrophic leaks are usually a result of stress, for example in pipe work. To identify the
potential for catastrophic leaks you need to examine pipe routing, support and vibration
elimination. EN378 provides guidance which should help to prevent catastrophic leakage –
see module 3 for more information on this.
Smaller leaks have many causes as outlined in the Illustrated Guide to 13 common leak
points. You should refer to this guide (and module 1) for solutions to these types of leaks.
Current level of service and maintenance
The standard of service and maintenance will be obvious from a visual check of the system
and examination of service records. Maintenance is vital to minimise refrigerant leaks. The
maintenance regime should be appropriate to the age, condition and type of system. Refer
to training module 2 for detailed information about maintenance to minimise leakage, and
adapt this information for the recommended strategy.
In addition good service practice is essential. This includes basic good practice such as:
•
•
•
Capping valves;
Changing gaskets when covers, flanges etc are removed;
Checking and changing seals when necessary.
Where leaks have occurred on the system you have surveyed, refer to the Illustrated Guide
for solutions and include these in the strategy.
Compliance with the F Gas regulation
The system operator (usually the end user) is responsible for complying with the F Gas
regulation. Information about this is provided in Module 1. The strategy must recommend
a regime in compliance with the F Gas regulation, but this should be seen as a minimum
standard – for many systems more frequent leak detection is beneficial. This is especially
so for systems:
•
•
•
•
With many joints;
Which have mechanical joints such as flares;
Which historically have a high leak rate;
With open drive compressors.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 8
Type, age and condition of equipment
You will need to consider the age and condition of the equipment when developing the
strategy for leakage reduction. It is less likely to be cost effective to make investments in
improvements to systems which are near the end of their life.
You should consider access to equipment – if access is difficult maintenance is less likely to
be carried out. This may also be a health and safety issue – a consideration which will
change the balance of investment vs. pay back.
Potential for leakage
In addition to examining current and historical leakage, you should also examine the
equipment for future potential for leaks. This includes considering:
•
•
•
•
•
The effect of vibration and whether vibration is correctly eliminated;
Pipe routing and support;
Whether pipes can chafe;
The potential for external damage;
The types of joint used.
Pipe work design for leak minimisation is covered in Module 3. Refer to this for information
which can be used in the strategy.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 9
4.4 Preparation of reports with recommendations for leakage
reduction strategies
Good clear reporting is essential if the strategy you develop is to be implemented. The
report should include:
•
•
•
•
•
•
•
•
The general impact of leakage and specifically which refrigerants have the greatest
impact;
Background information on the Real Zero project;
Indication of typical leak rates for the type of equipment surveyed and whether this
equipment is better or worse than similar typical systems;
How the survey was conducted and key findings, including photos;
An evaluation of the adequacy of current F gas records;
The recommended strategy for reducing leakage;
A business case for reducing leakage where applicable;
What to do next.
There is an example report format in Appendix 2 and an editable Word version is available in
YOUR REAL Zero TOOLKIT. You should not change the basic information in the template –
just add the specific information relating to the site you have surveyed.
You should follow up the report with a meeting with key personnel where possible to provide
practical advice on how to implement the strategy and work out an action plan. A follow up
survey is often beneficial to check the success of the strategy.
A copy of the report and the completed survey spreadsheet must be provided to the Institute
of Refrigeration
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 10
4.5 Reporting to the IOR for data collection purposes
Initial reporting
The IOR is collating information on leak reduction opportunities identified for data analysis
purposes to improve our knowledge of the potential for leak reduction. A summary of this
information will be shared with the Carbon Trust. The following information is required:
1. Each individual Site survey spreadsheet
2. Each individual Survey report and recommendations for leakage reduction strategies
These should be submitted electronically and files saved in the following format:
Your initials, end user name, site name, date.
For example: AAA, End User Name, Town, 18.11.07
Send reports to: ior@ior.org.uk
Follow up reporting
It is good practice to arrange follow up discussions with the end user and to gain feedback
on the recommendations implemented and savings achieved as a result of the survey. The
F Gas log will provide the evidence for this provided it is completed fully by the end user.
This data should form the basis of your follow up discussions.
Where available the updated F Gas log should be sent to the IOR for on going evaluation of
carbon savings achieved through the REAL Zero project.
It is a requirement of those who join the REAL Zero website listing to submit follow up
reports.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 11
Test your knowledge
Doing the following exercises will help to reinforce what you have read in this module.
Calculate the R134a weight in a liquid line 5/8” OD, 18 SWG, 47 m long.
Estimate the refrigerant charge in a system you have information about (pipe lengths and
diameters, evaporator and condenser models).
List the points you would include in a leak reduction strategy for a site you are familiar with.
Consider maintenance and design of the system.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 12
Appendix 1, Charge size calculations
The following information is helpful when calculating refrigerant charge size.
Volume of pipe work
V = (L x ID2 x π) / 4
Where
V = pipe internal volume, m3
L = pipe length, m
ID = internal diameter, m
π = 3.142
Example for a liquid line 35 m long, 1 3/8” OD,16 SWG:
1 3/8” = 1.375”
OD, mm = 1 3/8” x 25.4 = 34.9 mm
16 SWG pipe has a nominal wall thickness of 1.63 mm (see table below).
Pipe ID = 31.7 mm = 0.0317 m
V = (35 x 0.03172 x 3.142) / 4 = 0.0276 m3 (or 27.6 liters)
Calculating refrigerant weight from volume
M=Vxρ
Where
M = refrigerant weight, kg
ρ = refrigerant liquid density, kg / m3 (see below for densities of common
refrigerants)
Example for the liquid line above containing R404A:
M = 0.0276 x 1045 = 28.8 kg
Example for an evaporator (see label) running with R134a:
From the label information:
Evaporator volume is 1.2 dm2 = 1.2 litres = 0.0012 m3
M = 0.0012 x 1208 = 1.45 kg
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 13
Useful information
SWG 10 = nominal 3.25 mm, minimum wall thickness 2.93 mm
SWG 12 = nominal 2.64 mm, minimum wall thickness 2.38 mm
SWG 14 = nominal 2.03 mm, minimum wall thickness 1.83 mm
SWG 16 = nominal 1.63 mm, minimum wall thickness 1.47 mm
SWG 18 = nominal 1.22 mm, minimum wall thickness 1.09 mm
SWG 19 = nominal 1.02 mm, minimum wall thickness 0.918 mm
SWG 20 = nominal 0.914 mm, minimum wall thickness 0.823 mm
SWG 21 = nominal 0.813 mm, minimum wall thickness 0.731 mm
SWG 22 = nominal 0.711 mm, minimum wall thickness 0.640 mm.
Pipe, outside
diameter, inches
¼
3/8
½
5/8
¾
7/8
1 1/8
1 3/8
1 5/8
2 1/8
2 5/8
3 1/8
3 5/8
4 1/8
Pipe, outside
diameter, inches
0.25
0.325
0.5
0.625
0.75
0.875
1.125
1.375
1.625
2.125
2.625
3.125
3.625
4.125
Refrigerant
Density, kg / m3
R134a
1208
R404A
1045
R407C
1045
R410A
1068
R22
1206
Pipe, outside
diameter, mm
6.35
8.255
12.7
15.875
19.05
22.225
28.575
34.925
41.275
53.975
66.675
79.375
92.075
104.775
Consult the refrigerant supplier for information about other refrigerants.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 14
Appendix 2, Example Report
This example indicates the type of information to be provided in a Site Survey Report. The
text highlighted will need to be completed by you in an editable version of this report format
available in YOUR REAL Zero TOOLKIT .
Refrigerant Leakage Reduction
Site Survey Report
Site name and location
Date
Authors: names and company
Contents
1. Executive Summary
Page
2. Introduction
Page
3. Summary of Survey Information
Page
4. Compliance with Regulations
Page
5. Recommended Strategy for Leakage Reduction
Page
6. What to do Next
Page
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 15
Section 1
Executive Summary
This report has been prepared by name who has undertaken training in refrigerant leakage
reduction based on the Institute of Refrigeration’s REAL Zero project.
This report provides recommendations for a practical strategy to reduce leakage at site
name and location. It is based on information from a survey carried out at the site at the
request of site contact name.
The equipment at site name and location comprises summary of equipment. The typical
leak rate for this type of equipment is ??%. The equipment at site name and location had
an average annual leak rate of ??% between add dates. The major issues highlighted by
the site survey are:
•
List main issues
It is recommended that:
•
List main recommendations.
Your refrigerant use and costs
The records viewed at the time of the survey for systems on this site show that they had replaced
a total of xxkg of refrigerant over the past xx months. This is the equivalent of a total carbon
emission of xxx tonnes at an estimated value of £xxx (indicative list price). These estimates were
calculated by the REAL Zero Carbon Emissions Calculation tool which is available at
www.realzero.org.uk. See table below:
Pack Ref
Refrigerant
Type
Number of
Leaks
Recorded
in Site Log
Total
Refrigerant
Usage kg
Period
(Months)
Number of
Leaks
Detected
at Site
Survey
Estimated Total
Refrigerant Cost
Over Period
Recorded £
Total CO2
Emissions
Equivalent
kg
1
2
3…
TOTALS
Full details are provided in the remainder of this report.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 16
Section 2
Introduction
In the UK the negative effect of refrigerant leakage on the environment is equivalent to the
emission of over 3 million tonnes of CO2 per annum. Leakage also causes an average
reduction in system performance of up to 20%.
The Real Zero project (Refrigerant Emissions and Leakage Zero) was initiated by the
Institute of Refrigeration, supported by the Carbon Trust and the RAC industry to provide
practical guidance on reducing leakage. The project has provided training for leak reduction
specialists, guides, tools and a comprehensive website (www.realzero.org.uk).
The survey at site name and location has been carried out using the tried and tested format
developed by the Real Zero project. Information about reasons for leakage and pro active
leakage reduction provided by the project team has been used in the development of the
strategy included in this report.
Section 3
Summary of Survey Information
The site survey is a standard format developed by the Real Zero project to capture the
information required to develop a practical leak reduction strategy. It comprised:
•
•
•
•
A visual examination of the refrigeration plant;
A leak test using a hand held electronic leak detector of readily accessible joints. Note –
this is not a full leak test of the entire plant;
An examination of the F Gas log and other service records;
Discussions with site personnel who have day to day experience of the operation and
service of the RAC equipment.
The spreadsheet below shows the information recorded during the site survey.
Insert site survey record spreadsheet using insert object. If providing a printed version,
include it as an appendix.
The table below is extracted from the information supplied as the F Gas log for this site and
is a summary of the leaks and refrigerant usage:
Add table summarising refrigerant additions, removals and leaks from the F gas log (for
large amounts of data, include only a part summary, or place the table in an appendix).
The environmental impact in terms of carbon dioxide equivalent from the refrigerant leakage
on this site is ?? kgCDE over a period of xx months.
A number of issues relating to system design, installation, service and maintenance have
been identified during the site survey which impact on leakage. They are summarised in the
next sections. Include information about:
•
•
•
•
Current and historical leakage
Current standard of service and maintenance and its impact – positive and negative – on
leakage
Age and condition of equipment;
Compliance with F Gas regulation.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 17
Design and Installation Issues
•
Add information here with photos if applicable.
Operation, Service and Maintenance Issues
•
Add information here with photos if applicable.
Section 4 Compliance with the F Gas Regulation
Under the Fluorinated Gas (F Gas) regulation the systems on this site require a leak test add
info about the obligation and the minimum frequency of testing. Leak tests must be logged,
plus leak repairs and retests. Refrigerant charged and recovered must also be logged.
Add information about compliance and recommendations for maintaining records in future
(using REAL Zero F gas log if necessary).
Section 5
Recommended Strategy to Reduce Leakage
Refrigerant leakage impacts on operation of the system, its reliability and the operational
cost. This site has an estimated leak rate of ??% which is higher / lower than typical for this
type of application (??% of charge per year 1) – this will have a significant impact on
performance and cost. Include information about the total cost of this rate of leakage if you
can using the REAL Zero carbon emissions calculator.
Recommendations for improved service and maintenance
o
o
Modifications to the current maintenance scheme or a new maintenance
regime where necessary;
A complete service if necessary, for example to cap valves, carry out a
thorough leak test.
Recommendations for re work or replacement of components or systems
o
o
o
o
o
Pipe work improvements;
Joint changes, e.g. from flares to brazed joints;
Components changes, e.g. rotolok valves;
System replacement;
Improved access.
Issues related to HCFC replacement
o
Replacement of seals or gaskets which often leak more with the replacement
oil and refrigerant.
1
BNCR36: Direct Emission of Refrigerant Gases, provided as part of Defra’s Market Transformation
Programme.
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 18
Include the business case if applicable (see module 1).
Section 6
What to do Next
This report is the first stage in your recommended programme to reduce refrigerant leakage
and hence improve the performance and reliability of your RAC systems and reduce their
financial and environmental costs.
The next stage should be to discuss this with your refrigeration service and maintenance
contractor. There is a Guide available on the Institute of Refrigeration website which will
help you to do this (see www..realzero.org.uk/other resources: Appointing and managing
refrigeration contractors)
To ensure that a successful leakage reduction strategy is implemented you will need to
develop an action plan and put in place a process to review reductions achieved. Regular
monitoring of your F Gas logs will provide the evidence for this review, provided it is
completed fully by all contractors working on your equipment. A follow up survey after a six
or twelve month period may be beneficial to check the success of the strategy.
The Institute of Refrigeration is collating data related to the REAL Zero surveys to help
monitor effectiveness of this project. You will be invited to share feedback on
recommendations implemented and savings achieved as part of this on going monitoring
(data will be used to report in summary to the Carbon Trust on carbon saved by the sector).
Add information here about your future involvement, recommended action plan, follow up
survey etc.
Your name
Company
Date
REAL Zero Leak Reduction Training Module 4
Reducing refrigerant leakage through site specific surveys and advice
© Institute of Refrigeration 2009
page 19
REAL ZERO CASE STUDY 1
Refrigeration Systems in the Retail Sector
The retail sector, including supermarkets, is one of the largest users of F-gas (fluorinated greenhouse
gas) refrigerants. In the UK, leakage of HFC refrigerants from supermarket refrigeration systems is
estimated to have been 769,000 kg in 20051. Under the F Gas Regulations, operators of refrigeration
and air conditions (RAC) systems containing more than 3kg of HFC refrigerants are required to
perform regular leak testing and must not add more refrigerant without first identifying and repairing
the source of the leak. There are also strict requirements on recovery of refrigerant from systems,
recording of refrigerant use and labelling of equipment. A REAL Zero site survey can help operators
ensure that they comply with the F Gas Regulations and reduce potential and actual sources of
refrigerant leakage.
Supermarket Site Survey Case Study
The refrigeration systems in a medium sized supermarket were surveyed using the REAL Zero
methodology. The systems comprised low and high temperature refrigeration packs, with multiple
condenser units. The systems were around 5 years old and charged with R404A refrigerant.
Although the refrigerant leakage rate was lower than the average for the sector, the survey identified
a number of leaks and other faults. There was also evidence that both packs were short of
refrigerant charge, leading to reduced operating efficiency. The available F Gas logs and site
maintenance records did not demonstrate that leak testing had been carried out at the required
frequency (twice a year), nor did they specify the location for leaks that had been detected and
repaired. Several recommendations were made for improving maintenance and leak testing regimes
and reducing the future leakage potential.
Leak testing was carried out using hand held leak
detectors that were capable of detecting leakage rates as
low as 5g/ year. New leaks found included a significant
leak in the Schrader valve used for charging refrigerant
on the end housing of the liquid line filter drier, a leaking
Pressure Relief Valve (PRV) and a leaking flare joint at
the inlet to a filter drier. Additionally there was visual
evidence of past leakage from a Receiver outlet valve
and a drier outlet, as evidenced by oil stains. Caps were
missing on several valves and bolts were also missing in
some locations. Recommendations were made to the
client for the repair of leaks, replacement of missing
bolts and the fitting of caps to all valves.
The analysis of refrigerant leakage and the associated carbon emissions and financial impact are
shown in the table below. The costs shown include only the cost of replacement refrigerant – in
practice the costs associated with equipment downtime and repair and possible damage to perishable
goods could be much higher.
Pack Ref
Refrigerant
Type
Leaks
Recorded
in Site Log
Refrigerant
Additions
(kg)
Record
Period
(Months)
New Leaks
Detected at
Site Survey
Refrigerant Cost
Over Period
Recorded (£)
Total CO2 Emissions
Equivalent
(tonnes)
A
R404A
1
11
12
1
209
41.6
B
R404A
1
24
12
1
456
90.7
C
R404A
0
0
12
1
0
0
D
R404A
1
1
12
3
36
TOTALS
© Institute of Refrigeration 2009
0
27
5.3
3
692
137.6
www.realzero.org.uk
REAL ZERO CASE STUDY
Conclusion
The site survey identified that leak testing was not being carried out in full compliance with the F Gas
regulations, as well as detecting several leaks and shortage of refrigerant. The report provided
recommendations on practical steps to repair existing leaks and reduce the potential for leakage in
the future. Good design practice and effective maintenance regimes will minimise the financial cost
and environmental damage caused by refrigerant leakage.
REAL Zero Site Survey Process
REAL Zero site surveys are undertaken by advisers who have received training and assessment in
refrigeration leakage reduction skills. They are RAC professionals who are members of the UK
Institute of Refrigeration and may operate within a service and maintenance company, or as
consultants. A site survey comprises:
•
•
•
•
A visual examination of the RAC
plant
A leak test of readily accessible
joints using a hand held electronic
leak detector
An examination of the F Gas log
and other service records
Discussions with site personnel
who have day to day experience of
the operation and service of the
RAC equipment
The client is provided with a comprehensive report that includes:
• Executive summary and analysis of the carbon and financial impact of refrigerant leakage,
based on site records
• Benchmarking of refrigerant leakage (comparison with the average for the sector)
• A review of site compliance with F Gas Regulations, including logs and record keeping, with
recommendations for improvements where appropriate
• Identification of leaks and potential leakage points found during the survey, together with
design or installation issues that may affect leakage
• Recommendations for resolving leaks and other problems identified during the survey
• A review of the site service and maintenance strategy
Refrigeration and Air Conditioning systems are responsible for significant emissions of Global
Greenhouse Gases, resulting from their energy consumption and leakage of HFC and HCFC
refrigerants. In the UK the emissions due to leakage of HFC refrigerants from all types of stationary
refrigeration and air conditioning systems was estimated to be equivalent to 3,555,000 tonnes of
CO2 in 20051. REAL Zero is a UK Institute of Refrigeration initiative to help RAC system owners and
operators to identify sources of refrigerant leakage and to take practical steps to reduce it. For more
information on REAL Zero visit the website at www.realzero.org.uk
1
AEAT (2004), Emissions and Projections of HFCs, PFCs and SF6 for the UK and Constituent Countries, Report No. AEAT/ED50090/R02
© Institute of Refrigeration 2009
www.realzero.org.uk
Conditions of Use of REAL Zero website and material
The guidance and calculation material can be freely downloaded and used by all
persons.
Copyright remains the property of the REAL Zero project, the IOR and the
Carbon Trust and permission must be sought before items are reproduced,
distributed or extracted for publication purposes.
The IOR accepts no liability for errors and omissions.
Material on this site may be subject to updates and further development and we
therefore require that all users register before downloading.
The IOR and Carbon Trust reserve the right to contact users of the website to
assess its usefulness and estimate its effectives in helping to save carbon
emissions.
The IOR may contact users with updates and information about advances in
refrigerant containment and events related to material on this website, unless
specifically asked not to do so.
Inclusion of an individual or company on the list of advisers does not constitute
endorsement of that person or business. The listing provide evidence that the
individuals named have successfully completed a training course.
IOR January 2009