Halon extinguisher for overfired stove?

[DanCorcoran]

The best I've heard from those who've done it was to toss in a couple inch thick bag of soaked newspapers, or a modest sized bath towel that was wet but not dripping. The steam displaces the oxygen an things dwindle down.

I'd like to hear from anyone who has tried 'Purple K'.

From what I remember in the Navy '68-'72, purple K was a very fine powder that was corrosive. I don't recall by what mechanism it put out fires, but it was horrible to clean up. I have an old, small, hand-held Halon extinguisher (the gauge still reads in the green) that I wouldn't hesitate to use (unless I was in a telephone booth).

Our mainframe computer room at work (not Navy) had a huge Halon-dump system which was intended to displace all of the oxygen. The dump switch was a large red button by the exit door. One of our cleaning contractors wasn't paying attention one day and mistook the red button for the button that released the door lock to exit the room. He hit the switch, released the Halon, sounded the alarms from Hell, and shut down the mainframes. Needless to say, everyone in that room ran for the exit asap. It only cost us $50,000 (in the early 1990s) to recharge the system.

We relocated the switch and labelled it in several languages...

 

[cwill]

We have halon fire suppression in all of our races cars. Its considered an ABSOLUTE last resort because it will knock the driver out from lack of oxygen. ie: car upside down with fire in the drivers compartment and you cant get out. in a home setting i agree with Jake. Go for a dry extinguisher first. Halon seems overkill....effective but really overkill

 

[remkel]

So I am sitting here thinking what would be the best way to quash an over fired stove problem happening or about to happen. How about a halon extinguisher??? Any thoughts....anyone use one already???

Dave

Although halon is an excellent extinguishing agent it is definitely not the way to go. Halon kills a fire by disrupting the chemical reaction between the fuel/air/heat in the fire. The wonderful thing about halon is that it does not leave any residue which is the reason it was used in many electronics fire protection applications, but becomes an asphyxiant at relatively low concentrations. If I remember correctly, a lot of electronics rooms were equipped with SCBAs in the event the system had to discharge. the more common forms of halon used for fire protection applications are Halon 1211 (BROMOCHLORODIFLUOROMETHANE) and 1301 (BROMOTRIFLUOROMETHANE).


Do I think the concentrations in a fire extinguisher would get to that level? Perhaps not, however, I would not use the halon without having the proper protections in place. Oh, and it is an ozone depleting material.

A dry chemical extinguisher (ABC) would probably be the better choice, or some people actually use the old water extinguishers. Watch out with the water depending on your stove material.

 

[firefighterjake]

The best I've heard from those who've done it was to toss in a couple inch thick bag of soaked newspapers, or a modest sized bath towel that was wet but not dripping. The steam displaces the oxygen an things dwindle down.

I'd like to hear from anyone who has tried 'Purple K'.

From what I remember in the Navy '68-'72, purple K was a very fine powder that was corrosive. I don't recall by what mechanism it put out fires, but it was horrible to clean up. I have an old, small, hand-held Halon extinguisher (the gauge still reads in the green) that I wouldn't hesitate to use (unless I was in a telephone booth).

Our mainframe computer room at work (not Navy) had a huge Halon-dump system which was intended to displace all of the oxygen. The dump switch was a large red button by the exit door. One of our cleaning contractors wasn't paying attention one day and mistook the red button for the button that released the door lock to exit the room. He hit the switch, released the Halon, sounded the alarms from Hell, and shut down the mainframes. Needless to say, everyone in that room ran for the exit asap. It only cost us $50,000 (in the early 1990s) to recharge the system.

We relocated the switch and labelled it in several languages...

Purple K is generally found in BC-rated fire extinguishers (good for flammable fuel and gas fires and electrical fires -- not so good for use on ordinary combustible fires which would include wood, paper, plastic, etc.) . . . most of the ABC and BC chemicals are corrosive -- perhaps not to the point of Aliens blood corrosive, but corrosive over time. Purple K affects the fire on a chemical basis.

For normal household use . . . I stand by my earlier assertion . . . an ABC rated dry powder extinguisher would work well.

 

[henkmeuzelaar]

>
For normal household use . . . I stand by my earlier assertion . . . an ABC rated dry powder extinguisher would work well.

>

Does the "dry powder" act by cutting off the oxygen supply (i.e. by blanketing or by releasing a displacement gas) or does it react chemically with flames and/or hot surfaces?

In the last case (i.e. reaction with hot surfaces) could it leave any residue or cause permanent discoloration of the stove walls?

Henk

 

[Lumber-Jack]

So I am sitting here thinking what would be the best way to quash an over fired stove problem happening or about to happen. How about a halon extinguisher??? Any thoughts....anyone use one already???

Dave

Frankly I think using any kind of fire extinguisher for an "over-fire" is overkill. (A chimney fire is a different mater).

Here's what I do and why I do it.
We all know how hard it is to get a good hot fire with unseasoned wood, on the other hand we also know that really dry wood has a propensity to burn too fast and hot sometimes.
Well, because the wood I have is so dry it's often nip and tuck whether I'll get an over-fire condition happening when I load my woodstove up full for overnight burns, so because it is such a ongoing concern I had to come up with a reliable, yet simple, solution.
First of all. when I load the stove up for long burns, I always take care to watch the temperature gauge for a good while to see if continues to climb, drops, or remains steady before going to bed. Even with the air intake feed closed completely sometimes the stove temp will continue to climb if I loaded in some particularly dry wood, or some of the wood has a lot of resins or pitch in them which will burn like gasoline. If it continues to rise then I know I have the beginnings of a potential over-fire.
There have been a few suggestions already in this thread about how to either starve the fire by plugging the secondary air intake, or open the stove door to allow cold air in to cool the fire, however neither is a great solution if your goal is to let the fire burn on it's own and hit the sack or leave the house.
What I came up with, that works like a charm, is to keep some green (not seasoned) wood on hand and if I notice the stove temp continuing to rise into the "over-fire" zone, instead of remaining steady or dropping, I'll just place one (that's all it takes) of these green logs in the stove and the temperature will, without fail, start to drop. It's that easy, It has worked for me every time so far. No need to throw in any wet rags or douse the fire with fire extinguisher, just place in one unseasoned log and the over-fire condition starts to reverse itself nice and gently.
The one caveat with this system is I must leave enough room for that "one" more green log to fit in the stove.

Anyway, as I said already, because our wood is so dry we face this (over-fire) problem daily, and so everybody in the house is aware of the it and takes preventative steps to see that it doesn't happen, and really the only time it can usually become a serious problem is when loading up a hot stove with dry wood on a large bed of coals. (eg. over night burns)

 

[basod]

I'm pretty sure when halon was banned from manufacter the military specifically navy bought up stockpiles of it as thats whats used most shipboard control fire suppression.
every power plant control rm and processor rm I've seen built before the mid 90's had halon system installed, now most are looking a viable upgrade options due lack refill material.
Newer systems use FM200 not sure of its chemical compostion but believe its same principle without the toxicity issues of Halon.
Only been scared once a few weeks ago with the Clydesdale had all the secondary tubes glowing orange. It seemed counter intuitive at the time but i grabbed a piece of slab wood that had been rain soaked and threw it and fire quickly came down in temp.
Most extinguishers discharge with such velocity that i'd be scared of blowing everything out of the firebox, not to mention the mess from a dry chemical stuff goes everywhere. Iwas glad i had one under the sink when I truned the wrong stove burner on to boil water a few years ago, the cast iron pan on back burner had some bacon grease that lit up while I was in the other room- I pay attention when turning on the stove now.

 

[firefighterjake]

>
For normal household use . . . I stand by my earlier assertion . . . an ABC rated dry powder extinguisher would work well.

>

Does the "dry powder" act by cutting off the oxygen supply (i.e. by blanketing or by releasing a displacement gas) or does it react chemically with flames and/or hot surfaces?

In the last case (i.e. reaction with hot surfaces) could it leave any residue or cause permanent discoloration of the stove walls?

Henk

Mostly the dry powder affects the fire on a chemical basis.

I suppose it's possible it could leave some discoloration . . . more likely it's just going to leave one helluva mess as the powder is wicked fine and will get everywhere . . . word to the wise . . . if you're pushing your firegear into the back of your SUV and it's being pushed up against a fire extinguisher make sure the pin has not fallen out unless you enjoy spending quality time vacuuming up dry powder from the back of your SUV . . . just saying . . .

 

[remkel]

>
For normal household use . . . I stand by my earlier assertion . . . an ABC rated dry powder extinguisher would work well.

>

Does the "dry powder" act by cutting off the oxygen supply (i.e. by blanketing or by releasing a displacement gas) or does it react chemically with flames and/or hot surfaces?

In the last case (i.e. reaction with hot surfaces) could it leave any residue or cause permanent discoloration of the stove walls?

Henk

Mostly the dry powder affects the fire on a chemical basis.

I suppose it's possible it could leave some discoloration . . . more likely it's just going to leave one helluva mess as the powder is wicked fine and will get everywhere . . . word to the wise . . . if you're pushing your firegear into the back of your SUV and it's being pushed up against a fire extinguisher make sure the pin has not fallen out unless you enjoy spending quality time vacuuming up dry powder from the back of your SUV . . . just saying . . .

Dry chemical extinguishers do nothing more than smother a fire- they create a barrier on the surface of the fuel and interrupt the fuel's access to oxygen. If you have a bucket of sand you would get the same extinguishing effect as a dry chemical extinguisher. The only effect is the starving of oxygen to the fire. Halon, on the other hand, actually interrupts the chemical reaction between the fuel/oxygen/heat.

 

[NH_Wood]

Were talking over fire not chimney fire right?
The first thing to do is turn the blower on high ( assuming you have one).
If you can plug the secondary air intake with some aluminum foil that will usually shut down the fire pretty quickly. I have tried this once and it worked well, temp started dropping almost immediately.

+1 - choking the secondary inlets with foil really worked here as well. Cheers!

 

[firefighterjake]

>
For normal household use . . . I stand by my earlier assertion . . . an ABC rated dry powder extinguisher would work well.

>

Does the "dry powder" act by cutting off the oxygen supply (i.e. by blanketing or by releasing a displacement gas) or does it react chemically with flames and/or hot surfaces?

In the last case (i.e. reaction with hot surfaces) could it leave any residue or cause permanent discoloration of the stove walls?

Henk

Mostly the dry powder affects the fire on a chemical basis.

I suppose it's possible it could leave some discoloration . . . more likely it's just going to leave one helluva mess as the powder is wicked fine and will get everywhere . . . word to the wise . . . if you're pushing your firegear into the back of your SUV and it's being pushed up against a fire extinguisher make sure the pin has not fallen out unless you enjoy spending quality time vacuuming up dry powder from the back of your SUV . . . just saying . . .

Dry chemical extinguishers do nothing more than smother a fire- they create a barrier on the surface of the fuel and interrupt the fuel's access to oxygen. If you have a bucket of sand you would get the same extinguishing effect as a dry chemical extinguisher. The only effect is the starving of oxygen to the fire. Halon, on the other hand, actually interrupts the chemical reaction between the fuel/oxygen/heat.

With all due respect I believe this statement is wrong (but only partly wrong) . . . according to my "Bible" . . . The Fire Protection Handbook (19th edition, 2003) "Smothering, cooling and radiation shielding contribute to the extinguishing efficiency of dry chemical, but studies suggest that a chain-breaking reaction in the flame is the principal cause of extinguishment." (Chapter 4, Section 11 "Chemical Extinguishing Agents and Application Systems")

That said . . . I could always be wrong . . . perhaps a newer edition has revised this statement.

 

[henkmeuzelaar]

+1

The dry chemical in ABC dry powder extinguishers appears to be most often mono ammonium phosphate, a popular fire retardant.
As Jake says, there are chemical reactions going on as well. One of the reactions promoted by mono ammonium phosphate is increased char formation during the combustion process of solids (e.g. plastics and wood).

Chars are amazingly difficult to burn, especially at low oxygen levels. Similar char formation reactions in heat shields allowed the re-entry of space capsules without burning up in the atmosphere. Even today, many of the booster rockets carrying things into space use synthetic throat materials that turn into char and keep the extremely hot exhaust flames from eating through the rocket's metal housing, I believe.

Henk

 

[DanCorcoran]

"“Smothering, cooling and radiation shielding contribute to the extinguishing efficiency of dry chemical, but studies suggest that a chain-breaking reaction in the flame is the principal cause of extinguishment.†(Chapter 4, Section 11 “Chemical Extinguishing Agents and Application Systemsâ€)

Wouldn't a chain-breaking reaction include both smothering (physically breaking the chain of oxidation, by starving the fire of oxygen) as well as chemical reactions which generate substances which also prevent oxygen from getting to the fire (another type of smothering)? In other words, isn't this sentence saying that of smothering, cooling, and radiation shielding, smothering is the principle cause?

If so, then a bucket of sand would provide the physical smothering, but not the chemically-induced smothering.

 

[henkmeuzelaar]

"“Smothering, cooling and radiation shielding contribute to the extinguishing efficiency of dry chemical, but studies suggest that a chain-breaking reaction in the flame is the principal cause of extinguishment.†(Chapter 4, Section 11 “Chemical Extinguishing Agents and Application Systemsâ€)

Wouldn't a chain-breaking reaction include both smothering (physically breaking the chain of oxidation, by starving the fire of oxygen) as well as chemical reactions which generate substances which also prevent oxygen from getting to the fire (another type of smothering)? In other words, isn't this sentence saying that of smothering, cooling, and radiation shielding, smothering is the principle cause?

Dan, trying to distinguish between what exactly is "chemical" and what is "physical" in combustion processes is often extremely difficult. Although most people understand combustion as primarily a chemical process (i.e. fuel plus oxygen produces combustion products plus heat). Under everyday combustion conditions the size of the objects being burned and the supply of oxygen (i.e. both physical factors) tend to control the combustion rate, not the chemical composition or even the temperature.

So, yes, when talking about the combustion of a material such as char, almost completely consisting of carbon, I can choose to talk about how strong the bonds between the carbon atoms in char are (they are!) and how that protects the char in a rocket throat from burning away (to some extent, yes!). Nonetheless, at temperatures of thousands of degrees Fahrenheit, it is also clear that these strong chemical bonds (typically breaking around 1200 F, or so, in the presence of oxygen) could not do so for more than an instant if not the very limited access of oxygen to the deeper char layers would slow the oxidative bond-breaking reactions down, notwithstanding the very high temperatures. After all, breaking these carbon bonds in the absence of oxygen takes many, many thousands of degrees F.

So, yes, you could try to make the argument that it is all "smothering" (which most people would probably understand to be a physical process) but without the very strong carbon-to-carbon bonds, the solid char would probably melt, or even evaporate, thus adding more fuel to the fire (or at least to the discussion.... .

If so, then a bucket of sand would provide the physical smothering, but not the chemically-induced smothering.

+1

(but that's not what Remkel said.......)


Henk

 

[DanCorcoran]

"If so, then a bucket of sand would provide the physical smothering, but not the chemically-induced smothering.

+1

(but that’s not what Merkel said…....)

Henk "

Yes, that's the point I was making: that Remkel was correct that sand would smother a fire, but incorrect in that ABC extinguishers do indeed do more than sand does. I was agreeing with you, but not referring to char.