Fire extinguishers

Thanks Roy - that is a help!

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

RoyJ wrote:

The way we learned it (U. S. Coast Guard) and was able to remember it was:

A = Ash (wood, paper, etc) B = Boil (liquids) C = Current (electricity) Nothing special for D, but is used for metals.

RoyJ wrote:

That may depend on where you live, and whether or not your shop is attached to your home. I'm talking residential in western WA..

My homeowners insurance co (Pemco) would *increase* my rates if I add a sprinkler system in my detached shop. They claimed that replacement cost of a sprinkler system would be more than not having one, hence the higher rates. I couldn't believe my ears. Same with a metal roof, security system, etc.

Now if my shop was attached to our house (primary residence) I'd get the discounted rates. Thinking about connecting the two with a covered walkway .

Snarl

Whoops. You got my 'draft' version of this. I had changed it to 'one of the reasons...' Yes it was banned because of Ozone depletion issues, but unless I'm misremembering, it had already been taken out of some applications because of it's excellent ability to remove the oxygen from an enclosed space (precisely the same reason it was a great fire extinguisher). Remember, as long as you have something to breathe, your mind won't give much warning that there's no Oxygen until you keel over unconscious....which is a point you made well. That means that while you're standing there admiring the great job you did knocking down the fire, unless you get some fresh air in the space, you're starving your body and brain of Oxygen, with predictable results.

Pete

This is not an issue with hand-held extinguishers. You cannot carry enough inert gas to displace oxygen to a dangerous degree in anything but a closet-sized room or blanket effect. You're talking about 10s of cubic feet released into 1000s or more.

Actually, properly designed "whole room" halon systems worked on about 8% concentration in the air. one of the reasons that halons were so good as extinguishants. In contrast, the Argon system we now use in our computer rooms works at a design concentration of 40%. This needed serious attention to over-pressure vents to avoid reducing the effect of the inert gas flooding by blowing all the doors, windows and roof out of the computer rooms!

Incidentally, the Argon system we are using dumps about .2% CO2 into the air as well. Allegedly, this will stimulate the Vagus nerve and make people in the room breath harder. Haven't yet been in the computer rooms during a fire, so I don't know weather it's true. I think I'd do a runner when the alarms went off anyway.

Mark Rand RTFM

I use carbon dioxide for one reason: because it's clean. Some people will argue that powder has a greater fire extinguishing capability than carbon dioxide. Per kilogram this is probably true, and powder guards against re-ignition, which carbon dioxide does not. But an extinguisher is only effective if you're prepared to use it. Having seen the abominable mess that powder extinguishers make, I would need to be faced with a fairly serious fire before I would be willing to use one. But carbon dioxide I'm happy to be a bit more casual with, which is a good thing as things often burst into flames when I'm around.

Best wishes,

Chris

It is CO2 buildup in our lungs that causes the breathing response. I saw a great demo of this years ago on TV where the person was breathing in and out the same air in a bag. When just the bag was used he couldn't do it for very long. When a CO2 filter was placed between the bag and his mouth he just breathed in and out until he passed out and fell off the couch he was sitting on. Really instructive. ERS

But the Halon isn't displacing the oxygen in the air of the confined space, it's chemically blocking the oxygen from reacting to whatever fuel and heat are trying to burn. If anything is "displacing the oxygen" in the room, it's the fire that was going pre-Halon-discharge that burned it all up.

If you started with normal 21% oxygen in the air without a fire, the Halon will displace some of the air, but the remainder (with the Halon mixed in) will still have a decent amount of oxygen left in it.

The rule is that if the Halon system discharges, fire or not, drop everything and get out of the room and worry about the why later.

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According to Bruce L. Bergman :

However, Halon is heavier than air, so what is inhaled will stay pooled in the bottom of your lungs, reducing the surface area available for oxygen intake.

And once you are out, put your head lower than your lungs and breathe for a few cycles to flush the Halon from the bottom of your lungs.

We had Halon in our computer center (where I worked for quite a while), but the Army rules made us shut it down and replace it with dry-pipe water instead. It never was tripped, but the cost of an unneeded trip was always in everyone's minds. (I don't know where that Halon went -- two big tanks of the stuff, but it was somewhere which had a higher priority than we did. :-)

Where my wife worked, however (a tri-service agency), they had

Enjoy, DoN.

Lots of gases in air are heavier than air. They don't pool in your lungs.

Did a little more digging, and found this, which seems to be a good synopsis of the whole thing.

Basically, the newer versions of Halon are much less nasty that the original. Halon 104 (carbon tet) was discontinued because of its nastiness (not just as an extinguisher) Halons don't 'displace' the oxygen, they 'steal' it, and the process is driven by the heat of the fire. Newer Halons, and the compounds created by their use in fighting a fire are much friendlier to humans than 104 was, but are just as hard on Ozone.

Pete

Smokers and computer rooms do not mix.

If they can pin it on him, the $100,000.00 bill for refill gas, parts (squibs and rupture discs) and labor from one of the dumps and a gentle "Don't worry, we'll just deduct 10% from your salary for the next forty years..." should do the trick. Cure him of his drug addiction right fast.

After the first dump, I'd have installed video surveillance everywhere, then for the second dump you'd have proof. That stuff is WAY too expensive to play around.

Though that system sounds like it was improperly designed - the ones at the phone company had both smoke detectors and rate-of-rise heat detectors, and you had to trip both to initiate an automatic dump. The fire would get another minute or two to build before one of the heat sensors went, but a simple dusty smoke detector wouldn't cause a false dump. And the fire would still be small enough to stop.

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This is true in the chemistry of the fire and its extinguishment. But in your lungs respiring, the mechanism is simply displacement, which is not going to approach anything like suffocation potential from dumping Halon

Amen!

She now says that only one was a smoker. The other was "an idiot" (no more details), and this was perhaps twenty years ago that the last one happened.

As for the video surveillance -- this place worked with highly classified materials, so such surveillance would be a serious no-no.

That sounds like a good design.

Enjoy, DoN.

Wow those sound nice!

Yep - a machine a company I worked for and helped to design (high level design) used Taunt caps in it. Remember the PC's catching on fire - caps in backwards - We had some marked backwards. It dumped a whole room full and ran off some workers. We got to replace the boards and the Halon.

At GM outside the paint storage shop was a massive CARDOX (r) liquid CO2 system. It had 100,000 US Gallons in it. It dumped 25,000 upon the alarm and you had about 5 seconds to get out the doors or be frozen. In 5 seconds the 75,000 gallons of CO2 hit the room and turned to gas! Naturally in the paint shop was only brass but wow.

I'd rather not shatter on a floor if I were to die in a fire!

Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Mark Rand wrote:

D = Dumbbell works for me - good one!

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Dave Young wrote:

CO2 works great, but you need a LOT of the stuff. It has to blanket the flammable material until it has cooled off. A 50 Lb bottle on wheels is quite good. A 5 Lb hand-held bottle is too small when you have large amounts of fuels around. 5 Lbs in an engine compartment or vehicle interior, where the CO2 is confined can work well.

Not just aluminum and electronics, it will corrode EVERY bare metal surface, with the possible exception of hard chrome, and do it way faster than you can clean everything up. I had a dry powder bottle burst in a closed car, and it was quite a mess.

I got a bunch of retired water/air units on eBay. They are expired, so you can't use them where required for code or insurance. These have 5 gallons of water pressurized with compressed air. I have only used one once, when turkey grease caught fire in the kitchen oven while heating a pizza. I have to say, it put that fire out in milliseconds! You wouldn't want to use it on live electrical equipment or a lake of fuel, but for putting a lot of water onto a burning substance, it sure did the job. I'm thinking of putting garden hose nozzles on them so I can get a mist or a stream, as needed. You can, of course, get these new and certified by the fire extinguisher outfit. Depending on the hazards at your place, you may need several types, for combustible metals, fuels, electrical, etc.

Jon

Yeah, heat carbon tet to the right temperature and it forms Phosgene! Not too nice to have around. No immediate effects, about an hour later you drop dead.

Jon