Extinguisher for gases

[vinaydeep]

I was going through NFPA -10 and it is stated that Dry chemical powder can be used for flammable gase fires.
I wonder under what conditions will it be applicable as gases dont have shape and they will occupy the whole volume. The best remedy will be to cut off the fuel source

can anyone elaborate on the usage and the conditions of use

Afd

[fire49]

Maybe if it was In an enclosure???

Otherwise use appropriate extinguisher for what is actualy on fire

[DeputyChiefGonzo]

Dry Chem can be used to extinguish a flammable gas fire coming from either a pipe or an enclosure, such as an appliance.

[GTRider245]

Dry Chem can be used to extinguish a flammable gas fire coming from either a pipe or an enclosure, such as an appliance.

This. Most people don't understand or believe that it is possible, however it can be done. If you have a flammable gas fire that is under pressure, let's say a puncture in the sidewall of a tank or maybe a relief valve, you can apply ABC to the base of the plume and the pressure of the leaking gas will carry the agent through the plume and extinguish the fire. Onviously, you would then be left with a leaking flammable gas that will follow the properties of physics, so hopefully you have a plan as to what to do at this point.

The situations where I have done this (in training) were when you have a faulty relief valve on a LP tank and want to replace it (under pressure) and when you want to plug a leak in the side of a tank. Both can be done under the cover of a hose stream with little risk to the firefighter performing the task.

I will see if I can find the videos.

[vinaydeep]

Thank you very much. I hope you get a video to demonstrate application.

Afd

[BennyT373]

I believe NFPA claims this as Dry Chemical because the fumes are burning on the chemical. The Dry chemical displaces the oxygen in the air in the immediate area... hence why it chokes you up so much, even without direct contact.

[DeputyMarshal]

I believe NFPA claims this as Dry Chemical because the fumes are burning on the chemical. The Dry chemical displaces the oxygen in the air in the immediate area... hence why it chokes you up so much, even without direct contact.

NFPA doesn't "claim" this, that it's just the way it is.

FWIW, dry chem works by inhibiting the chemical chain reaction between fuel, oxidizer, and heat -- not by excluding oxygen. When you introduce it into the flames, it's interferes with the reaction and stops the chain of combustion.

[BennyT373]

Claims was definitely the wrong word usage... and I didn't mean it excludes it, but the CO2 smothers the O2...

I probably should have used some bigger terminology lol. But with flammable liquids its the vapors of the air burning. Take the O2 away from the fumes...no fire.

Thanks Marshal for keeping me straight lol