Generator Wall or Exhaust Thimble
- Thread starter spsnyder
- Start date
- Status
cripple
Senior Member
- Location
- Santa Fe, New Mexico
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
Maybe this will help:
Fire Inspection and Prevention Guidelines for Generator Exhaust Stacks
Problem
The penetration of the roof deck (or the wall) by the exhaust stack of a generator provides a source of heat and ignition for any combustible materials nearby.
Background
A fire occurred in the federal building at 715 Peel St., Montreal, at approximately 13:30, Friday, December 21, 2001 The fire started in the wood deck roof which was installed over the concrete roof deck of the top floor of the seven-storey building. Early estimates are that the loss will be nearly $1.3 million. The cause of the fire was the exhaust stack for the standby generator that was installed with less than 75 mm (3?) clearance to the combustible roof deck.
There have been other similar fires in recent years, some involving a major loss. The common cause has been generator exhaust stacks installed too close to combustible materials.
The problem can remain undetected for some time because the normal monthly test (1 hour) is often too short to raise the exhaust system to its maximum operating temperature, 538?C, (1000?F). When the engine is run for longer periods, the stack will heat up to the maximum operating temperature and can ignite nearby combustibles. (Most of the reported fires have occurred during extended power outages, or extended load tests.)
A further complication of this sort of installation is that repeated exposure to heat during the monthly test will pyrolyse nearby wood, thereby reducing its ignition temperature and increasing the likelihood of a fire in the future.
Recommendation
This Bulletin is intended to assist property managers and custodians in verifying the installation of the exhaust stack for their emergency and standby generators.
Custodians and property managers should inspect each and every generator installation and engine-driven fire pump installation to ensure that the exhaust stack is at least 230 mm (9?) from any combustible material. Combustible material may include (but is not limited to) wood framing, wood enclosures, roofing felt, tar, insulation, patches, and other construction materials.
?Generator exhaust stacks should be inspected to ensure the following:
◦that they do not contact any combustible material; or
◦that they do not pass through any combustible material, insulation, or roof covering; or
◦if they do pass through combustible material, that they are adequately isolated by a ventilated metal thimble, masonry chimney construction, or by an insulated assembly certified for the application.
?Generator exhaust stacks should be provided with at least the following clearances:
◦230 mm (9?) from combustible materials
◦Roof penetrations should be provided with metal ventilated thimbles meeting the following requirements:
◦thimble at least 150 mm (6?) larger diameter than the diameter of the exhaust stack;
◦thimble extends at least 230mm (9?) above and below any roof construction.
?Wall penetrations should be provided with the following:
◦metal ventilated thimble not less than 300 mm (12?) diameter larger than the diameter of the exhaust stack;
◦metal or burned fire clay thimbles built in brickwork or other approved fireproofing materials providing not less than 200 mm (8?) of insulation
◦between the thimble and combustible material.
The above clearances may be reduced for insulated assemblies certified for lesser clearances.
The preferred installation should be through a non-combustible wall to the outside, and the stack attached to the side of the building with metal supports.
In addition, a management control program should be instituted to ensure that any work done on the roof or on the generator does not change the situation.
Adequate training and instruction of the custodial and maintenance staff should provide for ongoing observation as well as adequate corporate records to ensure that future changes or additions do not infringe on this fire separation.
Further Information
For further information, or for assistance with determining if an installation meets the necessary criteria, please contact our nearest regional office.
Fire Inspection and Prevention Guidelines for Generator Exhaust Stacks
Problem
The penetration of the roof deck (or the wall) by the exhaust stack of a generator provides a source of heat and ignition for any combustible materials nearby.
Background
A fire occurred in the federal building at 715 Peel St., Montreal, at approximately 13:30, Friday, December 21, 2001 The fire started in the wood deck roof which was installed over the concrete roof deck of the top floor of the seven-storey building. Early estimates are that the loss will be nearly $1.3 million. The cause of the fire was the exhaust stack for the standby generator that was installed with less than 75 mm (3?) clearance to the combustible roof deck.
There have been other similar fires in recent years, some involving a major loss. The common cause has been generator exhaust stacks installed too close to combustible materials.
The problem can remain undetected for some time because the normal monthly test (1 hour) is often too short to raise the exhaust system to its maximum operating temperature, 538?C, (1000?F). When the engine is run for longer periods, the stack will heat up to the maximum operating temperature and can ignite nearby combustibles. (Most of the reported fires have occurred during extended power outages, or extended load tests.)
A further complication of this sort of installation is that repeated exposure to heat during the monthly test will pyrolyse nearby wood, thereby reducing its ignition temperature and increasing the likelihood of a fire in the future.
Recommendation
This Bulletin is intended to assist property managers and custodians in verifying the installation of the exhaust stack for their emergency and standby generators.
Custodians and property managers should inspect each and every generator installation and engine-driven fire pump installation to ensure that the exhaust stack is at least 230 mm (9?) from any combustible material. Combustible material may include (but is not limited to) wood framing, wood enclosures, roofing felt, tar, insulation, patches, and other construction materials.
?Generator exhaust stacks should be inspected to ensure the following:
◦that they do not contact any combustible material; or
◦that they do not pass through any combustible material, insulation, or roof covering; or
◦if they do pass through combustible material, that they are adequately isolated by a ventilated metal thimble, masonry chimney construction, or by an insulated assembly certified for the application.
?Generator exhaust stacks should be provided with at least the following clearances:
◦230 mm (9?) from combustible materials
◦Roof penetrations should be provided with metal ventilated thimbles meeting the following requirements:
◦thimble at least 150 mm (6?) larger diameter than the diameter of the exhaust stack;
◦thimble extends at least 230mm (9?) above and below any roof construction.
?Wall penetrations should be provided with the following:
◦metal ventilated thimble not less than 300 mm (12?) diameter larger than the diameter of the exhaust stack;
◦metal or burned fire clay thimbles built in brickwork or other approved fireproofing materials providing not less than 200 mm (8?) of insulation
◦between the thimble and combustible material.
The above clearances may be reduced for insulated assemblies certified for lesser clearances.
The preferred installation should be through a non-combustible wall to the outside, and the stack attached to the side of the building with metal supports.
In addition, a management control program should be instituted to ensure that any work done on the roof or on the generator does not change the situation.
Adequate training and instruction of the custodial and maintenance staff should provide for ongoing observation as well as adequate corporate records to ensure that future changes or additions do not infringe on this fire separation.
Further Information
For further information, or for assistance with determining if an installation meets the necessary criteria, please contact our nearest regional office.
Should be ok... but just in case:
http://www.google.com/products?q=Insulated+Thimble&aq=f
I think the Insul-Flue ones are rated for up to 2100?
- Status