EFFECTIVE AND EFFICIENT AUTOCLAVING IN HIGHER EDUCATION
Notes by Peter James, Director, S-Lab 28/11/2014
These notes summarise the presentations and discussion at a workshop on autoclaves held at the
University of Warwick in October 2014. An Appendix tries to distil the material into guidelines for
autoclave procurement and use. The workshop was organised by S-Lab, in partnership with a
collaborative group that has been formed by HEFCE, SUPC, S-Lab and leading universities such as
Cambridge and Warwick to drive improvements in laboratory equipment performance. The
presentations can be viewed here.
Presentation by Joel Cardinal, Head of Energy and Sustainability, University of Warwick
Joel explained that Warwick was a top 10 university that is committed to high quality STEM (and
other) teaching and research, and to being a “living demonstration of the principles of
environmental sustainability”. It has reduced CO2e emissions by 34% compared to 1990, and has a
target of reducing absolute emissions by 60% compared to 2005/6. As a STEM-intensive university,
laboratory equipment has a large energy and carbon footprint and so Warwick is focused on
reducing this, both by internal action and by co-founding the collaborative group that had organised
the workshop.
Presentation by Peter James, Director, S-Lab
Peter noted the high financial and operating costs of autoclaves, and the fact that they account for a
significant proportion of the 15-25% of laboratory energy consumption that is associated with
equipment. He outlined an improvement methodology which S-Lab has developed to deal with cold
storage, and discussed its relevance to autoclaves. The methodology has four stages:
1. Satisfy (genuine) needs – science and technology teaching and research must always have
what they genuinely require but there is considerable evidence that this is often done suboptimally, in part because needs can be different than wants. Some relevant issues for
autoclaving are the effectiveness of waste separation so that only essential material is
autoclaved, and the potential for sharing so that total numbers can be rationalised.
2. Track activities – there is often limited knowledge about the nature and scale of laboratory
activities, even though better knowledge can be beneficial in many ways.
3. Eliminate waste – waste takes many forms. In the case of autoclaves it includes waste of
capacity and energy when autoclaves are only part-used (which can be prevented by
batching), and waste of energy when they generate steam eve n when not required.
4. Manage effectively – it is difficult to implement any of the preceding measures without good
management, which includes a holistic approach to the issues, clear objectives and
responsibilities, and standard operating procedures covering calibration, maintenance and
other topics.
Presentation by Janine Kimpton, Technical Services Centre Manager and Dave Hibberd, Workshop
& Infrastructure Manage, School of Life Sciences, University of Warwick
The School has 15 autoclaves in 8 locations across 3 sites, plus numerous bench tops. Some key
points are:
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There is an annual validation and service, with the latter being divided between in house
staff and an external contractor. This costs around £20,000 per annum.
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The autoclaves are remotely monitored, using an ABB 4 channel recorder. This provides
early warning of problems.
The main energy source is 2 gas steam generators, which service 6 high throughput
autoclaves. They run continuously for c 11 hours a day at full pressure (10 bar).
There has been significant rationalisation, with loads concentrated onto six high throughput
machines.
Janine compared and contrasted different types of autoclave steam supply. Gas fired steam
generators have high installation and maintenance costs, and require considerable energy to reheat
when turned off overnight. Hence, they are only sensible when they can be run most of the time and
are appropriately sized for autoclave loads. When this occurs, as at Warwick, they are the most costeffective and energy-efficient option.
There are two kinds of electric steam generators – low pressure ones which heat from cold (via
elements) as needed, and high pressure ones which heat a boiler to provide constant steam. The
latter use a great deal of energy and are seen as less desirable at Warwick. Low pressure units only
use significant energy during the heating phase of the run but can be slow to reach temperature.
Hence, they are best suited to intermediate use. (The total electrical power requirement to replace
the gas steam generators at Warwick would be c. 400Ah, which would require a costly upgrade to
the existing substation).
Another important consideration is location. Autoclaves produce radiated as well as convected heat
and a single machine can take ambient temp up to 30-35oC, creating uncomfortable working
conditions and/or requiring air conditioning. Cooling the chamber with water rather than air can
help but it is important that the water is recirculated.
Jon Lovell, Head of Waste, Wellcome Trust Sanger Institute
Jon described how Sanger:
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Has rationalised 19 autoclaves that ranged in size from 6000 to 10 litres into 5 600 litre and 2
250 litre units. (Their medium size makes batching much easier so that they can always be
operated near full capacity, and also increases resilience compared to a few large machines).
Runs about 13 batches daily, of which ten are waste, two medical and one glassware (much
less than in the past due to increased use of plastic).
Has moved to use aluminium rather than plastic containers (see below for discussion).
Has a two-stage autoclaving for some dangerous substances, e.g. typhoid virus.
He described relevant regulations which are:
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BS2646 Autoclaves for Sterilization in Laboratories – 30 years old but the only one that
definitely applies to laboratories.
BS3970 Sterilizing and Disinfecting Equipment for Medical Products – now withdrawn
although still mentioned.
BSEN285 Sterilization: Steam Sterilizers and Large Sterilizers – very specialised.
HSE PM73 Safety at Autoclaves - Free Download
CFPP01 (HTM2010/HTM01) Management and Decontamination of Surgical Instruments used
in Acute Care – too demanding for most HE applications but has several useful sections, e.g.
guidelines on purchasing laboratory autoclaves.
He also identified four key factors in choosing autoclaves:
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Size and Positioning – options are obviously influenced by available space, and contextual
factors such as heat load.
Usage - Dry Goods, Liquids, Fabrics, Waste (Nature of waste).
Ergonomics - Loading and throughput of machines, including manual handling issues.
Whole life costs – important to compare because some manufacturers sell at low margins
and compensate by relatively high charges for maintenance and spares. One solution is to
use third part maintenance companies. Equipment developed for medical use (which is very
regulated) is usually more expensive so important to get the specifications right.
Finally, he described how the NHS has a recognised role of Authorising Engineer (Decontamination),
abbreviated to AE(D). This is intended to provide impartial auditing and advice on all aspects of
decontamination – including cleaning, disinfection, and sterilising – of medical devices, including
autoclaves. (See article here). The role encompasses design of decontamination facilities,
specification and procurement of equipment, validation and testing and auditing. AE(D) registration
– which Jon has - is conferred by a panel, which is administered by IHEEM (Institute of Healthcare
Engineering and Estates Management), and requires attendance at the Institute’s Advanced Course
in Sterilisation Technology (ACIST). This covers standards and guidance; microbiology; validation;
steam sterilization; washer disinfectors; other sterilization and decontamination techniques, and the
role of the Role of AE(D). See below for further discussion of the relevance to HE.
Andy Evans, Sustainability Manager, VWR
VWR are generating comparative data on the cost, energy and water consumption, and other
operating parameters of a range of equipment. Autoclaves will be addressed in 2015. Key metrics
will be:
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Cycle time taken
Cycles/loads per day
Energy consumption (kWh/day)
Water usage (hard vs soft)
Servicing costs
Capabilities
Practice/components influence (e.g. containers)
Certifications.
Andy presented sample data on two units to demonstrate the variability in performance:
S (311L) – External Steam
P (450L) – Steam Gen
Water usage (m )
3.493
0.402
Water Cost (£)
2.69
0.31
Electricity (kWh)
78.875
64.375
Electricity (£)
6.31
5.15
CO2/tonnes
0.042908
0.033502
Carbon Cost (£)
0.51
0.42
Yearly Cost (£)
6,850.73
4,233.77
3
Discussion Points
Responsibility - Jon Lovell posed two questions, who is responsible for the safety of your site
autoclaves? And should universities have an AE(D) type role, either informally, or by having an
IHEEM registered individual? Several people commented that the NHS system can be rather
bureaucratic and/or just be a tick box exercise and therefore did not present an ideal model for
universities. However, there was a feeling that the importance of autoclaving is not always
recognised, and that in larger departments or facilities someone should have responsibility both for
safety, and tracking overall autoclave use. There was also considerable agreement that, whilst the
full course may be too much for HE, a simpler basic autoclave principles; key maintenance tasks
(daily, weekly and monthly); and management responsibility could be useful. (NB This is now being
set up by S-Lab, in association with Sanger).
Metal containers – Sanger has found a 10-15% improvement in cycle time (as aluminium is a better
heat conductor so that temperature is reached more quickly), and an increase in capacity. It also
thinks they are more secure to transport. However, there are disadvantages including higher initial
purchase cost, seal maintenance and increased weight (creating potential health and safety issues re
manual handling). Sanger has avoided the latter by lightweight designs but these are more fragile
and so need to be replaced more frequently.
Purchasing – several people stressed the importance of involving users when preparing
specifications and tenders. It can also be helpful to talk to vendors in the pre-tender period because
they have considerable knowledge of autoclave use. Guidelines for procurement and use e.g.
maintenance regimes would be helpful, as would more comparative data on energy use and other
parameters. (See Appendices for a first attempt at this). This needs to be on a standard basis e.g. per
litre to take account of variations in size.
Mixed use – there was disagreement on this. Warwick believe that it is bad practice to use the same
autoclave for media preparation and to treat waste. Sanger do mix these, and believe that good
operating procedures mean that autoclaves always remain sterile.
Appendix: Guidelines for Autoclave Procurement and Use
Procurement
Is a new autoclave really necessary? Can it be avoided e.g. by better use of existing equipment
through sharing or other means, managing waste streams so that non-hazardous waste is not
autoclaved?
Have users been consulted, and standard operating procedures consulted (or developed), during
preparation of specifications and tenders?
Are the autoclaves right sized for needs so that they always operate at full capacity? Have the
potential benefits of ordering two medium sized ones rather than a single large one been explored?
Have the whole life costs of different alternatives been properly calculated? E.g. by considering
energy consumption, any additional cooling, power supply or ventilation requirements, maintenance
costs.
Are different options being compared properly, e.g. by reference to type and volumes of waste
generated, likely usage patterns, standardised metrics (e.g. cost per kilo processed).
Has use of metal containers been considered and, if chosen, been risk assessed especially re manual
handling?
Are the outputs of this fully reflected in tender documents and criteria?
Use
Are their standard operating procedures for use and maintenance in place, and are these followed?
Is there a clear responsibility structure for autoclaving?
Is there effective waste separation so that only genuinely hazardous or unpleasant waste is
autoclaved?
Are loads batched so that units are always run near to full capacity?
Is equipment turned off or down whenever possible?
Is there an audit process to ensure that autoclaving is functioning properly?