TMG G1520
SIGNALLING EQUIPMENT
TEMPERATURE CONTROL
GUIDELINES
Version 2.0
Issued September 2012
Owner:
Chief Engineer, Signals & Control Systems
Approved
by:
Warwick Allison
Chief Engineer
Signals & Control Systems
Authorised
by:
Paul Szacsvay
Principal Engineer
Signal Research & Development
Disclaimer
This document was prepared for use on the RailCorp Network only.
RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be
sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the
copy of the document it is viewing is the current version of the document as in use by RailCorp.
RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes
any liability which arises in any manner by the use of this document.
Copyright
The information in this document is protected by Copyright and no part of this document may be reproduced, altered,
stored or transmitted by any person without the prior consent of RailCorp.
UNCONTROLLED WHEN PRINTED
Page 1 of 2
Engineering Guideline
Engineering Guideline
Signals
RailCorp Engineering Guideline — Signals
Signalling Equipment Temperature Control Guidelines
TMG G1520
Document control
Version
1.0
2.0
Date
2/04/2007
19/09/2012
Summary of change
First issue
Document number TMG G1520 applied. Cover pages
complying with TMA 400 Engineering Publications Manual
attached to front of document to facilitate publication.
Forming part of this document is the Signalling Equipment Temperature
Control Guideline dated 2 April 2007.
The original document consists of 17 pages.
© RailCorp
Issued September 2012
UNCONTROLLED WHEN PRINTED
Page 2 of 2
Version 2.0
Signalling Equipment
Temperature Control Guideline
TABLE OF CONTENTS
1
INTRODUCTION
3
2
TYPICAL TEMPERATURE RELATED PROBLEMS
3
3
EQUIPMENT TEMPERATURE REQUIREMENTS
4
4
HEAT GENERATED BY EQUIPMENT
5
5
LOCATION CASES
6
6
BUNGALOWS
7
7
BUILDINGS
8
8
MOUNTING OF EQUIPMENT
8
8.1
GENERAL EQUIPMENT
8
8.2
Q RELAY RACK MOUNTED EQUIPMENT
9
8.2.1
Track circuit equipment
9
8.2.2
Resistors
9
8.2.3
Relays
10
8.3
NS1 RACK MOUNTED TRACK CIRCUIT EQUIPMENT
10
8.4
G RAIL (OR TOP HAT RAIL) MOUNTED EQUIPMENT
12
8.4.1
Resistors
12
8.4.2
Ancillary equipment
12
8.4.3
Power supplies
12
8.5
19 INCH RACK MOUNTED
12
8.5.1
Power Supplies
12
8.5.2
Heat sensitive equipment
12
8.6
WALL MOUNTED
13
8.7
FLOOR MOUNTED
13
8.8
EQUIPMENT CONTAINING FANS
13
9
EXTERNAL EQUIPMENT
13
10
SHADE STRUCTURES
13
11
ROTARY ROOF VENTILATORS
14
12
AIR CONDITIONING
14
13
SPARE EQUIPMENT STORAGE
15
14
REMEDIAL ACTIONS
15
Appendix - Ventilation requirement calculations
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16
Signalling Equipment
1
Temperature Control Guideline
Introduction
This document provides guidelines on:
•
Lay out of equipment on racks for heat related issues.
•
Limits for heat loads in various types of locations and buildings.
The aim is to include temperature control as a significant factor when considering the
positioning of equipment on racks, within locations, bungalows or buildings.
Some areas experience higher temperatures due to their natural environment and
therefore need more effort to control equipment temperatures.
The results from temperature recording and analysis have shown that improved
ventilation provides the most significant measurable improvement to internal ambient
temperatures compared to double skinning or tropical roofs. However improved
ventilation also increases dust in locations.
Improving the thermal insulation of Signalling buildings and location cases can
reduce the amount of ventilation required.
Signalling buildings and location cases should move towards meeting thermal
requirements similar to the minimum star rating of the Nationwide House Energy
Rating Scheme (NatHERS). Detail of NatHERS is available on the Internet at
www.nathers.gov.au.
2
Typical temperature related problems
Prolonged exposure to operating temperatures at or near the equipment's rating is
known to reduce the life of electronic equipment.
Short-term ambient temperatures at or near rated maximums can cause:
• Increased sensitivity to electrical noise, which can lead to failure, if electrical noise
is present. CBI equipment like SSI and Microlok has exhibited this type of failure.
• Drift in operating parameters, which may cause permanent failure, intermittent
failure, or fail the equipment whilst it remains above a particular temperature.
Older telemetry systems have exhibited this type of failure. CSEE UM71 Txs lower
their output power available, CSEE UM71 Rxs pick up threshold increases.
• Shutdown the equipment due to built-in over temperature controls. Aldridge LED
signal lights, and power supplies have exhibited this type of failure
• Component failure. This type of failure has been reported for most types of
equipment.
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Signalling Equipment
Temperature Control Guideline
Long term operating temperatures (typically >45ºC):
• Reduced equipment life, which leads to an increased failure rate of the equipment.
Older Store 93 power supplies have had this type of failure. Equipment installed in
underground railway tunnel locations has also had this problem due to continuous
high ambient temperatures.
Large temperature cycles (day/night changes of >25ºC):
• Reduced equipment life, which leads to an increased failure rate of the equipment.
Older telemetry systems have exhibited this type of failure.
• Different expansion and contraction rates for the materials can result in stress
causing internal connection problems that cause permanent failure, or intermittent
failure, or temperature dependant failures of the equipment. Older telemetry
systems have exhibited this type of failure.
• Instability in temperature compensation circuits. TI21 track circuits may exhibit this
type of failure.
Low temperatures causing water to condense or drip onto equipment:
• At low temperatures condensation can occur on internal surfaces due to the
difference between wall or roof temperature (cold) and internal air temperature
(warm). Water can then drip on exposed equipment and cause failures. This
problem can also occur in external equipment.
3
Equipment temperature requirements
The initial part of this section provides minimum and maximum temperatures ratings
of commonly used equipment. These ratings do not include any de-rating to improve
longevity or reliability of the equipment.
Typical track circuit equipment ratings are:
• Jeumont Schneider track circuit equipment is rated for 0 to 70º C.
• TI 21 track circuit equipment is rated for 0 to 70º C.
• FS2500 track circuit equipment is rated for 0 to 60º C.
• CSEE UM71 track circuit equipment is rated for –30 to +70º C.
RailCorp Signalling Equipment specification SPG 1020 Power supply units for
Signalling Equipment - General requirements requires 0 to 70ºC temperature rating.
Commercial power supplies used are rated to 55ºC but are operated at a reduced
load to allow operation at 70ºC.
Q relays are type tested at 55ºC for most aspects and 60ºC for coil operation.
Westinghouse Mark IIIA SSI TFMs are rated for -20 to +60º C.
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Signalling Equipment
Temperature Control Guideline
Microlok II equipment is specified as –40 to +70º C but some ancillary equipment
associated with Microlok II is only rated to 55ºC. The 55ºC rated ancillary equipment
typically does not generate significant amounts of heat.
Most wiring used in signalling installations is V75 rated which means that the wire
including the heat rise due to the electrical current carried must be kept to less than
75ºC.
The SAK terminals are suitable for their full rating up to 85ºC. The Z series terminals
used with Microlok II are suitable for their full rating up to 75ºC.
A set of objectives to control these effects is:
• Normally operate the equipment no higher than 10ºC less than its rated
temperature for at least 90% of the time in the hottest month.
• Allow equipment temperature to reach its maximum rated temperature only on
days that reach 35 to 40º C.
• Keep the day night temperature change for the equipment to less than 25ºC.
• Provide buildings or location cases that are designed to extract the heat generated
by the equipment installed.
This guideline meets these objectives (as well as the Signals Standards
requirements) by trying to balance the heat loads of locations with the ventilation
provided and the protection from the heat produced by direct sunlight.
4
Heat generated by Equipment
The heat generated within signalling locations and buildings comes from the
consumption of electricity. Typically less than half the VA load of a location will be
dissipated as heat within the location as some power is fed into signal lights, train
stops, the rail ballast by track circuits, etc. The other reduction is due to the power
factor being less that 1. Typically the power factor is about 0.9.
An assessment of equipment generated heat gives:
Equipment
Heat dissipation estimate (Watts)
SSI Transformer (500VA)
20
Power Transformer
40 per kVA
SSI TFM
25
Microlok II card file (1/3 full)
20
Microlok II card file (2/3 full)
40
Audio Track Circuit PSU regulated
(Store 93).
25
Audio Track Circuit PSU unregulated.
12
Audio Track Circuit Tx
12
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Signalling Equipment
Temperature Control Guideline
CSEE UM71 Rx
6
TI21, FS2500 Rx
10
Jeumont Schneider PSU
15
Jeumont Schneider Tx
15
Jeumont Schneider Rx
3
General, relays etc
1 per relay. See Note.
Static Switch 5kVA
100
Static Switch >5kVA
250
UPS
75 per kVA
Note: Averaged value taking into account the percentage of energised relays and relay heat
dissipation.
5
Location Cases
Equipment installed in location cases is subject to wider temperature swings and
more extreme temperatures.
Standard location cases that do not have temperature control measures like doubleskinning, improved ventilation, or shade structures should have equipment rated for
at least 60oC. However 55oC rated equipment (that does not produce significant heat)
can be installed in the bottom half of the location.
Location cases that have temperature control measures like double-skinning, or
shade structures may have some ancillary equipment rated for 45oC but where
practical it should be rated for 55oC or more.
Location case sizes are defined in terms of single, double, or triple width. A door is
provided for each unit of width.
Location cases that have not had their ventilation upgraded are estimated to handle a
maximum of 80 watts equipment generated heat load per width.
The design approach is to use convection airflow from an air inlet vent at the bottom
(below equipment mounting level) to an air outlet vent at the top (above the
equipment mounting level) to remove heat.
Location cases should have one of the following treatments:
• New locations should be double skin with ventilation for 200 watts equipment
generated heat load per width. This is one inlet air vent below each door sized
approximately 150mm high by 800mm wide. The width should match the door
width. Outlet air vents should be of equivalent or larger size to the inlet air vents
and located above the highest equipment mounting point. Inlet vents can also be
provided low down on the sides of the locations and the vents under the doors
reduced appropriately.
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Signalling Equipment
Temperature Control Guideline
• Existing locations in original condition:
‰
Double-skin the location using an approved double skin location case design
that has the required level of ventilation.
• Existing locations with Tropical roof:
‰
Provide vented roof, with door and side vents to location case.
Or
‰
Double-skin the location using an approved double skin location case design.
Or
‰
Provide 300mm passive rotary roof ventilator and bottom inlet vents. This
requires 100 x 800mm of inlet vent below each door.
Location cases that have had their ventilation upgraded as above are estimated to
handle a maximum of 200 watts equipment generated heat load per width.
Locations must not have horizontal internal ceilings, all location ceilings should have
a slope of at least 2.5º (30mm drop in 620mm) to ensure condensation runs to the
side and does not drip onto equipment. This minimum slope is based on existing
location cases. A larger slope of 4º (45mm in 620mm) is preferred.
Internal ceilings of locations must not have any protrusions or points where
condensation can collect and drip from that are directly above equipment mounting
positions. Rafters or support members running across the line of slope especially
promote the forming of drips.
6
Bungalows
Standard concrete bungalows that do not have temperature control measures like
improved ventilation, or shade structures must have equipment rated for at least
55oC.
Concrete bungalows that have temperature control measures like additional shade
roof, and shade panels, or active cooling may have some ancillary equipment rated
for 45oC but where practical it should be rated for 50oC or more.
Bungalows that do not have proper ventilation should have a maximum of 330 watts
equipment generated heat load.
The typical maximum is 1000 watts equipment generated heat load for a properly
ventilated bungalow. However in exceptional cases the equipment generated heat
load can be up to 3000 watts provided that appropriate additional temperature control
measures are implemented.
Bungalows should have:
• A 400mm industrial rotary roof ventilator with 0.5 m2 of unrestricted inlet air
vents for the room in the bungalow. This normally means enlarging the door
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Signalling Equipment
Temperature Control Guideline
vent to 600mm wide by 700mm high, which combined with the wall vents
should meet the 0.5 m2 of unrestricted inlet air vents requirement. Suppliers
recommend that the inlet air vent area should be 4 times the throat area of the
rotary roof ventilator.
• Vandal resistant cages for the roof ventilators. The cages must not
significantly restrict the air flow.
or SkycoolTM heat reflective coating to reduce
solar heat gain. External walls are not painted, as it would make the
bungalows too prominent and may be cause for complaint by nearby
residents.
• Roof painted with Solacoat
7
TM
Buildings
Standard double brick signalling locations with 2.4m ceilings must have equipment
rated for at least 55oC.
Standard double brick signalling locations with ceilings higher than 2.4m may have
some ancillary equipment rated for 45oC but where practical it should be rated for
50oC or more.
Brick or large buildings with active cooling, additional ventilation or additional thermal
insulation have significantly better temperature control of the equipment than the
standard brick signalling locations. Ancillary equipment rated for 35oC may be used in
this case but where practical the equipment should be rated for 45oC or more.
The equipment generated heat load should be calculated based on the heat removal
provided.
Typically the permissible equipment heat load will be more than that of a bungalow
and thus a properly designed brick building is preferred to a bungalow on this criteria.
8
Mounting of equipment
8.1
General equipment
Signal Construction Specification SPG 0707 Specification Installation of equipment
racks and termination of cables and wiring Clause 2.2.2 requires:
• Equipment to be mounted between 300 and 1800mm above ground or floor level.
• Heat producing equipment mounted so it does not damage equipment above or
beside it.
The following sections detail the preferred method of complying.
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Signalling Equipment
8.2
8.2.1
Temperature Control Guideline
Q relay rack mounted equipment
Track circuit equipment
TI21 and FS2500 track circuit transmitters, receivers, and power supplies mount on
Q relay racking.
TI21 transmitter and receivers are 2 1/2 Q spaces wide. A 1/2 Q relay space must be
left between adjacent modules. This spacing is sufficient for normal installations.
FS2500 transmitters and receivers are 2 Q spaces wide. A vacant Q space must be
left between transmitters and other module types. The vacant Q space is preferred to
be on the right-hand side of the transmitter.
The standard minimum spacing of 50mm vertically between rows of Q relay racks is
adequate.
TI 21 track circuit
equipment
mounted
with
insufficient space
between
PSU
and 1st module.
8.2.2
Resistors
Positioning and mounting of resistors must address the heat that will be generated.
Resistors that may dissipate 3W or more and are operated at more than 1/4 of their
power rating must have 75mm of open space directly above them.
Mounting terminals and backing plates must be rated for 70ºC. The Weidmuller MK4
mulitpole terminal blocks are approved.
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Signalling Equipment
8.2.3
Temperature Control Guideline
Relays
Relays should not be fitted in the position directly above a resistor that requires open
space directly above it.
If relays are mounted in the row directly above track circuit equipment then a
minimum of one relay position in 3 must be left vacant, while one vacant space in two
is preferable.
8.3
NS1 rack mounted track circuit equipment
CSEE UM71 track circuit transmitters, receivers, and power supplies are installed on
the NS1 racking. The minimum vertical spacing between modules is 8mm. The
minimum horizontal spacing between columns is 50mm. The minimum vertical space
between modules is not sufficient when the modules produce more than 9 watts of
heat. The following vertical spacing rules apply for UM71 Track circuit equipment:
• Rx mounting: Rxs can be mounted with no space between Rxs. However Rxs
must have two vacant PFC block spaces below when mounted above CSEE
UM71 Tx, PSU or Jeumont Tx, PSU modules.
• Tx mounting: Txs must always have one vacant PFC block space below and
one vacant PFC block space above regardless of module mounted above or
below.
• PSU mounting: PSUs must always have one vacant PFC block space below
and one vacant PFC block space above regardless of module mounted above
or below.
• Rxs should be mounted below Txs and PSUs.
CSEE equipment
on NS1 racking
with insufficient
space between
Txs.
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Signalling Equipment
Temperature Control Guideline
Jeumont Schneider Impulse track circuit equipment is installed on the NS1 racking.
The minimum vertical spacing between modules is 8mm. The minimum horizontal
spacing between columns is 50mm. The minimum vertical space between modules is
not sufficient when the modules produce more than 9 watts of heat. The following
vertical spacing rules apply to Jeumont Track circuit equipment:
• Tx mounting: Txs must always have one vacant PFC block space above it.
• PSU mounting: PSUs must always have one vacant PFC block space above
it.
• Rx mounting: Rxs can be mounted with no space between Rxs and between
Rxs and relays or immediately below Txs or PSUs. However Rxs must have
two vacant PFC block spaces below when mounted above Jeumont Tx, PSU
modules or CSEE UM71 Tx or PSU modules.
• Relay mounting: Relays can be mounted with no space between Relays and
between relays and Rxs. However Relays must have one vacant PFC block
spaces below when mounted above Jeumont Tx, PSU modules or CSEE
UM71 Tx or PSU modules.
• Relays and Rxs should be mounted below Txs and PSUs.
• VDRs are considered to be equivalent to a vacant space.
189 watts of correctly
spaced Jeumont track
circuit equipment.
Each door width can
only handle 200 watts of
heat load, so the
equipment could be
spaced out further.
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Signalling Equipment
8.4
8.4.1
Temperature Control Guideline
G rail (or Top hat rail) mounted equipment
Resistors
Positioning and mounting of resistors must address the heat that will be generated.
Resistors that may dissipate 3W or more and are operated at more than 1/4 of their
power rating must have 75mm of open space directly above them.
Mounting terminals and mounting plates must be rated for 70ºC. The Weidmuller
MK4 mulitpole terminal blocks are approved.
8.4.2
Ancillary equipment
Ancillary equipment with temperature ratings of 55ºC or less should be mounted in
the lower half of the location, as the temperature rise is less in the lower half of the
location.
8.4.3
Power supplies
Power supplies must be installed in compliance with the orientation and spacing
recommended by the manufacturer.
In general industry, mounting rails are horizontal rather than vertical, which may
cause problems with ventilation of the equipment when mounting equipment on the
vertical mounting rail.
8.5
19 inch rack mounted
1U is a vertical rack spacing measurement, which is approximately 45mm (or exactly
1 3/4 inches or 44.45mm).
8.5.1
Power Supplies
Power supply sub-racks must have a minimum of 2U free space left above them and
a minimum of 1U free space left below them.
Generally power supplies are mounted higher in the rack.
Power supplies are considered to be heat-producing equipment.
8.5.2
Heat sensitive equipment
Heat sensitive equipment mounted in 19-inch racking must have a minimum of 1U
free space above each sub-rack and 1U free space below each sub-rack. No heat
producing equipment may be mounted within the 3U space immediately below the
heat sensitive equipment.
Generally heat sensitive equipment is mounted lower in the rack.
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Signalling Equipment
8.6
Temperature Control Guideline
Wall mounted
Wall mounted heat producing equipment must have a minimum of 75mm free space
below and on either side, and 150mm free space above it.
Equipment mounted on walls should be mounted so that it is not hard up against the
wall and preferably not mounted on a north or west wall. The recommended
minimum stand-off distance is 12.5mm.
Mounting is to comply with the orientation recommended by the manufacturer.
8.7
Floor mounted
Floor mounted heat producing equipment must have a minimum of 75mm free space
on either side, and 150mm free space above it.
Mounting is to comply with the orientation recommended by the manufacturer.
8.8
Equipment containing fans
Space must be left around the air inlet/outlet so that the air flow within 50mm of the
air inlet/outlet is not impeded. A 100mm space of unimpeded airflow is preferred.
Consideration should be given to the direction of the air flow to reduce dust entry.
Typically the fan should draw air from below the equipment rather than from above or
the side.
Space must be left to allow the replacement of fans and/or filters.
9
External equipment
Ensure that designs do not place equipment externally that has not been specifically
approved for external mounting.
10
Shade structures
Shade roofs need to be sloped to reduce the collection of heated air underneath the
structure. The slope should be between 10 to 18 degrees to allow the heated air to
escape. The low side should be on the North or West side depending on the
available natural shade. The low side should be toward the North if no other shade is
available. These guidelines are based on studies published by the CSIRO on shade
structures.
The roof slope can be reduced if the roof material is not solid and permits heated air
to rise through the roof.
Lysaght Louvamesh has been approved for use as part of shade screens. Vertically
mounted mesh is installed with its longway opening horizontal and strands sloping
outward and down. This is the manufacturer's recommendation for maximum shading
effect.
Provision of shade structures is secondary to the provision of proper ventilation.
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Signalling Equipment
Temperature Control Guideline
Location cases still need to have appropriate ventilation (like the vented roof, and
improved door and side vents) to allow internally generated heat to be removed.
11
Rotary roof ventilators
Roof ventilators are Type 4 Rotating wind driven roof ventilators as per AS 4740
Natural Ventilators - Classification and Performance. These are called by various
names including "whirlybirds" etc.
Rain resistance should at least meet Class B, with Class A preferred.
Effective aerodynamic area should at least meet Class 2, which is at least 50%
effective area.
Flow coefficient should at least meet Class 2, which is at least 50%.
Wind loading should be at least Level 2.
Industrial grade rotatory roof ventilators are to be used be they are more durable, and
provide a higher airflow rate for a given wind speed than domestic models.
The Hurricane Turbine series ventilators from CSR Edmonds have been approved.
One 300mm Hurricane Turbine ventilator can be used on location cases.
One or more 400mm Hurricane Turbine ventilators are used on bungalows and brick
buildings.
Ecopower Hybrid Turbine ventilators are induction motor assisted roof ventilators that
use the motor assist while the internal temperature is above a temperature set by a
thermostat. At lower temperatures they perform as a standard rotary roof ventilator.
The Ecopower Hybrid 300mm Hurricane Turbine ventilator has been used in some
installations but are not needed for usual situations. The current standard size for the
Ecopower Hybrid Hurricane Turbine ventilators is now 400mm diameter.
12
Air conditioning
Air conditioning should be provided only in extreme cases where the other means are
not effective or not possible. Signal Construction Specification SC 12 20 00 00 SP
(SPG 0708) Small buildings and Location cases sets the requirements for any air
conditioner provided. The air conditioner should have at least a 4 star energy rating
for cooling.
The building should have an insulation rating of at least R2.5 for an air conditioner to
be economically installed over its life cycle. Typical bungalows have an R value of
about 0.25. This means that air conditioners installed in bungalows will have to have
a much higher capacity to control the temperature on very hot days (as well as be
more in-efficient because of the inadequate building insulation).
Air conditioners should be rated for significantly more than the normal equipment
heat load. Twice the equipment heat load is considered appropriate.
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Signalling Equipment
13
Temperature Control Guideline
Spare equipment storage
Spare equipment is to be stored in an environment that does not shorten its life.
The storage environment should limit the maximum storage temperature to less than
70ºC. The minimum storage temperature should be more than -5ºC.
Nylon jacketed PVC internal wire (7/0.40) can be triggered to leak plasticiser due to
storage at temperatures above 70ºC.
14
Remedial actions
Priorities for work to improve ventilation for existing locations, or buildings should be
based on:
• Bungalows that currently have poor ventilation (that is undersized/no rotary roof
ventilator, or rotary roof ventilator with a door vent of less than 600mm by
450mm.)
• Quantity of Audio, and Jeumont track equipment with close spacing. (High heat
load)
• Quantity of CBI equipment (High heat load plus sensitive equipment).
• Locations in full direct sun from 9am to 4pm.
• Areas known to experience hotter temperatures like Western Sydney.
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Signalling Equipment
Temperature Control Guideline
Appendix - Ventilation requirement calculations
The appendix contains reference information that details how the ventilation
requirements were derived.
The heat transfer equation for air is:
Q= 0.05 W /Tc
Where:
Q is the airflow required in m3/minute.
W is Heat dissipated in Watts.
Tc is outlet air temperature rise above air inlet temperature in degrees Celsius.
Typical air speed for convection airflow is given as about 0.2m/s, which implies that
the air takes 10 seconds to flow from bottom to top of a location case.
Fixed grilles or louvre panels
Location case vents are Type 1 Fixed grilles, louvre panels as per AS 4740 Natural
Ventilators - Classification and Performance.
Rain resistance should at least meet Class B.
Effective aerodynamic area should at least meet Class 2, which is at least 50%
effective area.
Wind loading should be at least Level 2.
Location cases
Given an aim to limit heat rise in the location to 7ºC due to internal heating and
allowing up to 3ºC heat rise due to solar heat gain. This is based on using a double
skin location case.
Expected maximum internal heat load for a location case is 200w per door width.
For a single width location case the calculation is:
Q= 0.05 x (200) / 7 = 1.4 m3/m
Inlet area = Q / Speed (in m/minute)
Inlet area = 1.4 / (0.2 x 60)
Inlet area = 0.12 m2
Using a Class 2 Effective aerodynamic area vent then the area of the vent needs to
be 0.24 m2.
This means about 150mm by 800mm air inlet per door width. The outlet size needs
to be equal to or greater than the inlet area.
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Signalling Equipment
Temperature Control Guideline
Bungalows
The normal maximum internal heat load for a bungalow is 1000w although an
electrical power room with a large UPS could be up to 3000W.
Given an aim to limit heat rise in the location to 3ºC due to internal heating and
allowing up to 7ºC heat rise due to solar heat gain.
For a 3.3m by 5.5m bungalow the calculation is:
Q= 0.05 x (1000) / 3 = 16.6 m3/m
This equates to a 400mm Edmonds Hurricane Turbine Ventilator rotary roof ventilator
in a 6 km/hour breeze under typical conditions. The nominated flow rates for rotary
roof ventilators are stated for ideal conditions and actual flow rates are more likely to
be around 75% of the stated values. This is based on information provided by CSR
Edmonds.
Inlet air vents need to be 4 times the throat area of the rotary roof ventilator, which is
4 x π x 0.22 (4 x π x r2) or about 0.5m2.
This means effective air inlet of at least 8 off, 250mm by 300mm wall vents and a
600mm by 700mm door vent based on the use of Class 2 Effective aerodynamic
area vent.
If the heat load is 3000W then a 700mm rotary roof ventilator or 2 off, 500mm rotary
roof ventilators are required. The inlet vents required would be 12 off, 250mm by
300mm wall vents, and a 600mm by 900mm door vent.
2/04/2007
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