1. #1
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    Default wwyd? Commercial Stove exhaust vent fire

    While investigating a recent smell of smoke in a commercial building, me and my crew got to discussing exhaust vent fires. The smoke smell we were investigating had that burned food smell to it. We were able to make access to the roof and found an exhaust vent for a commercial kitchen that had a heavy build-up of grease on it. There was no fire.

    Now the question to all of you, have any of you encountered a grease fire in an exhaust stack of this sort and if so, what method did you use to extinguish it? For those that haven't, what would you think would be the best way?
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    Hmmm...

    Dry Chem I think would be the medium of choice.

    Wondering if the chimney-fire tactic of PPV with a shot of Dry Chem up the chimney (exhaust) would be appropriate. That would minimize dry chem in the kitchen.

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    We have a lot of restaurants in our area. The truck will try to get it with dry chem. At the same time the engine's will stretch a line in and if needed another to the roof. In New York all Restaurant must have a schematic of their duct work.
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    Dry chem extinguisher.
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    Dry Chem
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    Dry Chem
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    Dry Chem

    i agree.
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    Dry chem is a good choice. I just wonder how the fire got past the fusible links in the Vent Hood Suppression system? Glen.

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    Dry chem. is usually the best way of extinguishing the fire, and dont forget to check the area around the ductwork for any extension that may have occured due to radiant heat or poor joints in the ductwork.

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    We had something sort of like this about a year ago. On the roof of a chemical company that makes castor oil, they have a vent hood on top of this long cylindrical (sp?) piece wich turned out to be a catalyic converter. We were about 2 blocks away we could see this thing glowing with a flame coming out of the top. It looked like a candle. We had the plant workers shut the power off then we used about 200 lbs of dry chem to extinguish. The TIC was used to check for any extension below.
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    Good Topic - never once in my life have I considered a fire in a commercial vent hood & system. (Not that many eateries in our first due anyway - it's THAT rural !!)

    All that being said I have a question on tactics (and don't laugh . . . much )

    Since most of the Commercial systems I have seen in the past are protected by halon (or whatever there replacing halon with now), wouldn't a CO2 extinguisher be a better choice than Dry Chem ??

    Using the vent's natural "chimney effect", why not shoot CO2 up the stack and dispel the O2 the fire is feeding on (I'm guessing that the CO2 would dissipate too fast to be effective) ?? This would have way less contamination to the cooking area below vs. dry chem though.

    Anyhow - just an uneducated musing.
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    I agree with everyone else: Dry Chem is the best way to extinguish a fire of this type.

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    We had a fire like that in a fast food place. Would not have been much to it if the employees had pulled the emergency switch when they ran out the back door. We ended up using a dry chem and a hoseline. Made a real mess in the kitchen.
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    Default 20 lbs? dry chem

    Quote Originally Posted by Trkco1 View Post
    We had something sort of like this about a year ago. On the roof of a chemical company that makes castor oil, they have a vent hood on top of this long cylindrical (sp?) piece wich turned out to be a catalyic converter. We were about 2 blocks away we could see this thing glowing with a flame coming out of the top. It looked like a candle. We had the plant workers shut the power off then we used about 200 lbs of dry chem to extinguish. The TIC was used to check for any extension below.
    200 lbs or is it 20 i dont think to many depts have 200 lbs of dry chemcial?

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    Dry Chem...and watch out below when that grease starts melting and runnin back down the stack! Makes napalm look good!

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    Quote Originally Posted by N2DFire View Post

    Since most of the Commercial systems I have seen in the past are protected by halon (or whatever there replacing halon with now), wouldn't a CO2 extinguisher be a better choice than Dry Chem ??

    Using the vent's natural "chimney effect", why not shoot CO2 up the stack and dispel the O2 the fire is feeding on (I'm guessing that the CO2 would dissipate too fast to be effective) ?? This would have way less contamination to the cooking area below vs. dry chem though.

    Anyhow - just an uneducated musing.
    What types of businesses do you have with mostly Halon systems? We find these mostly were in records rooms and computer areas. I have yet to see one in a commercial restaurant. The new systems are a class of their own (class K) but before these all we had were dry chem systems in eateries. We just had a two fryolator fire a few months ago ina Wendy's where the manager had been told to never use the dry chem system. They evidentally knew it would cause alot of cleanup andshut them down for a day. We walked in and pulled the system initiation device and the fire was out in 20-30 seconds. Thankfully it did not reach into the duct. But dry chem is the method of choice for a contained grease fire in the hood.

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    Quote Originally Posted by N2DFire View Post
    Good Topic - never once in my life have I considered a fire in a commercial vent hood & system. (Not that many eateries in our first due anyway - it's THAT rural !!)

    All that being said I have a question on tactics (and don't laugh . . . much )

    Since most of the Commercial systems I have seen in the past are protected by halon (or whatever there replacing halon with now), wouldn't a CO2 extinguisher be a better choice than Dry Chem ??

    Using the vent's natural "chimney effect", why not shoot CO2 up the stack and dispel the O2 the fire is feeding on (I'm guessing that the CO2 would dissipate too fast to be effective) ?? This would have way less contamination to the cooking area below vs. dry chem though.

    Anyhow - just an uneducated musing.

    The older types are actually a dry chemical system. The new systems are wet chem. You can tell by looking at the nozzles. Dry chem looks like shower heads for lack of a better explanation, wet chem are small tip nozzles with little caps on them, usually orange.

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    Quote Originally Posted by RFDACM02 View Post
    We just had a two fryolator fire a few months ago ina Wendy's where the manager had been told to never use the dry chem system. They evidentally knew it would cause alot of cleanup andshut them down for a day. We walked in and pulled the system initiation device and the fire was out in 20-30 seconds. Thankfully it did not reach into the duct. But dry chem is the method of choice for a contained grease fire in the hood.

    Lessee,any outfit more concerned with how much time it would take to clean up after a fire was contained as opposed to how long it would take to rebuild a whole restaraunt after a fire burned longer than it took to set off the installed FF system.
    Sounds like they should spend a little more time on preventative maintenance of the exhaust hoods to get the grease out and reduce the chances of fire to begin with.

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    Quote Originally Posted by Cessna View Post
    Dry chem is a good choice. I just wonder how the fire got past the fusible links in the Vent Hood Suppression system? Glen.
    That is what I was thinking.

    But if it does.....3d fire.....grease.....Dry Chem. Unless you have a steam hose handy for some reason..............Actually....CO2 might work if it is a small fire, and it wouldn't leave the mess. Worth a shot to avoid trashing the kitchen area with powdered salt.

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    if the kitchen is updated to a UL300 system (wet chemical), they should have on hand a wet chemical extinguisher (class k). this should aid with any small fires in the kitchen. (it would assist the wet chemical blanket, much like a class b foam). anything larger in the kitchen should obvious be dealt with a handline.
    I would still take the dry chemical to the roof...mainly because i dont have a class k on a rig

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    Quote Originally Posted by N2DFire View Post
    Using the vent's natural "chimney effect", why not shoot CO2 up the stack and dispel the O2 the fire is feeding on.
    I am uneducated on this as well, but I would go for dry chem first, the powder will be carried along by the chimney effect - I am wondering if the cold C02 would screw up the chimney effect and stall the airflow convection before it reaches all of the fire. Fire would be unhappy, but not extinguished.

    Neighboring agency at my last city of residence lost two fast food restaurants in two years to these fires. The first one was leveled. They saved the structure on the second one but the owner still tore the place down. No idea what was up with their auto suppression systems if they had them.

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    Quote Originally Posted by ElectricHoser View Post
    I am uneducated on this as well, but I would go for dry chem first, the powder will be carried along by the chimney effect - I am wondering if the cold C02 would screw up the chimney effect and stall the airflow convection before it reaches all of the fire. Fire would be unhappy, but not extinguished.

    Neighboring agency at my last city of residence lost two fast food restaurants in two years to these fires. The first one was leveled. They saved the structure on the second one but the owner still tore the place down. No idea what was up with their auto suppression systems if they had them.
    Most vent hoods, at least in our area, are only about 10 foot tall at the most. Maybe 15 in a big restaurant. The natural expansion of the CO2 from the pressure drop out of the extinguisher would most likely be enough to carry it completely through the stack. Or, you could coordinate a double CO2 attack from the top and the bottom, as long as there was not a concern of "pushing" the fire onto the other party.

    I have a friend who works on cooking equipment for Burger King, and his take on it was that if the Ansul system fails to extinguish it, then a serious neglect of routine maintenance is usually a culprit. Not necessarily maintenance of the Ansul system, but infrequent cleaning of the actual hood and vent to remove grease buildup. I've helped him install some of these fryers in the past, and it sure does get nasty around them........
    Last edited by SWLAFireDawg; 01-21-2007 at 10:31 AM.

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    Even the burger-flippers at McDonald's probably have some McWackers.

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    Now that's a bad azz toy!!

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    Or a seriously huge restaurant
    I am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.

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