Primarily for general aviation discussion, but other aviation topics are also welcome.
By cockney steve
#1711859
In continuance of @patowalker 's tale.

Another motor-trader who later finished his PPL and led me astray :P
worked for a major auto- electrical supplier. The trade- counter had a wall behind dividing- off the workshop and stores. staff entered /exited either end of the counter . Now as recounted by Donald, CO2 extinguishers usually have a black cone-shaped delivery- nozzle, some 50 Cm long. Staff took full advantage, especially around the "annual service" time so, a nozzle would appear, a cloud of "smoke would issue, whilst a loud croaking voice was repeating "Exterminate, Exterminate" (Daleks were "hot" at the time)

Well, a bonfire in the yard got a bit out of hand, as a drainpipe up the wall of an adjoining unit had "sucked" up flames and was now blasting them at telephone wires, directly overhead.

Someone had presence-of -mind to grab the nearest extinguisher....aimed and a dying HAaaah, issued forth..drop, run across "stage " behind trade-counter..exit stage -left to retrace steps carrying a fire-extinguisher. HAaaaaah....bewildered customers spent many minutes watching employees ignoring them whilst scuttling back and forth ferrying extinguishers to the end of the building next to the yard. I STR the trusty hose settled that one and Post Office had to replace overhead wires that were strangely burnt above a drainpipe and guttering!
H&s was a secondary consideration in those days, but they made sure that at least some extinguishers were ready for their intended purpose :P
By riverrock
#1711860
Foam was fairly effective on an oil fire when I did the training - basically it forms a layer over the top, smothering it. You do need to get the foam in contact with the seat of the fire, which can be a problem, and its conductive so you don't want it near electricity.

CO2 has the issue of also smothering the pilot. They also don't last very long.

Standard water extinguishers are surprisingly weak. I've had more powerful water pistols.
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By VRB_20kt
#1711861
The "waste paper bin" demo is one that I remember to this day and it's one I do with the Scouts. Amazing that half an extinguisher won't kill even a small fire like that!

Sent from my K6000 Pro using Tapatalk
By Bill McCarthy
#1711878
In my early days in the mob we had ox blood (stowed in 10 gallon drums) as a foam making agent. A venturi pickup spill was spiked though the drum top, mixing took place in the nozzle. We used to pour a drumfull overboard whilst drifting with the tide on Beira patrol - to drive the sharks nuts.
On submarines, fire was our main fear and the fire fighting agent was AFFF (Aqueous Fire Fighting Foam) - there was very little foam produced and the principle was that the mixture adhered to any surface to smother the fire. Main switchboard breakers all had plug in points for CO2.
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By BoeingBoy
#1711886
Do not under any circumstances use the Halon in an enclosed space. If you discharge it inside the cabin in flight you will be dead before you hit the floor.
They have been outlawed for years.


They have indeed been outlawed for years but not for aviation use. It's the only extinguisher that effectively deals with electrical fires by starving them of oxygen, and that is the key to the other statement in that you are indeed unlikely to survive the use of one in flight.

Back in the eighties before the health and safety brigade came out from under their fairy grotto's the airline I worked for conducted its fire training at the local county fire service training centre. There, real firemen, using real fires and real smoke (not your imitation whale oil) trained us to evacuate real bodies (they usually fought back) using real breathing apparatus and eject them down the slide.

Part of that training included using BCF extinguishers on wall and pan fires measuring around two metres square. The first lesson we were taught was NEVER aim a BCF at the base of the fire. This was demonstrated by a fireman in a full metal suit releasing the extinguisher at a pan fire from about six feet away. The jet blast hit the flames curling them over the top back to engulf him from head to foot. Aim at the top of the fire and quickly work your way to the base. Don't forget the BCF robs the fire of oxygen and you are doing the same as putting a blanket over it.

The other demonstration that sticks with me to this day is what BCF smells like once it's hit the fire. Forget all the stuff above about how toxic it is. None of that matters. It's not toxic before it hits the fire but it smells exactly like tear gas once it has. (Yes, the airline used to spray us with that too in the security lectures so I know what the comparison is).

BCF is still the safest extinguisher for all round use in an aircraft but beware that when it says 'use in a ventilated space' they are not kidding. If you let one off on naked flames in a light aircraft cockpit, you will be dead before you hit the ground if you don't open a window or door and take a big breath first. Remember it's starving the fire of oxygen so that includes you too, along with filling the cabin with a gas that I guarantee you will not breath in twice!
By riverrock
#1711890
@BoeingBoy - Halon chemically interferes with the combusion process, stopping the fuel and oxygen interacting. It doesn't deprive or displace the air of Oxygen. As such, you can still breath.
It doesn't smell nice but it is significantly less toxic than the smoke which would have been coming from the fire.

Either your training was wrong, or you're miss remembering.
By dangerous pete
#1711905
I'm merely passing on the instructions given to me in fire crew training. We have a Halon extinguisher on one of the fire trucks and we are instructed not to use it. . It will be removed in due course.
By Bill McCarthy
#1711915
When HMS Splendid was in build at Barrow-in-Furness we had temporary Halon bottles distributed throughout the boat - set off one and it would trigger a group of them. Some Herberts, fancying a breath of fresh air would set the group off leading to an evacuation. No real hurry, just thin out and get up top. Nobody died.
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By BoeingBoy
#1711936
riverrock wrote:@BoeingBoy - Halon chemically interferes with the combusion process, stopping the fuel and oxygen interacting. It doesn't deprive or displace the air of Oxygen. As such, you can still breath.
It doesn't smell nice but it is significantly less toxic than the smoke which would have been coming from the fire.

Either your training was wrong, or you're miss remembering.


I'm not going to argue over the finer points of a chemical reaction. We were taught that the fire can no longer function due to it not being able to source oxygen. Same thing.......??

You can't breath it in post contact with flames. I don't care if there's oxygen in the air or not. We were instructed to stand downwind of a tray fire and breath in the fumes post contact. One breath was enough! I don't know anyone who stood there admiring the view.

I stick by my post.
By cockney steve
#1712205
In the 1960's (and many years prior) buses carried "Pyrene" brass syringe-type extinguishers. They were about a foot long with a nozzle at one end and a tee- handle( pump) at the other. They squirted Carbon Tetrachloride, which is an extremely good extinguishant....unfortunately, when burnt, it produces highly toxic, not to say lethal, Chlorine gas. They were outlawed, as were Thawpit and Dabitoff home "dry- cleaning" products, which were simply bottles of the same stuff.

Legend has it that a smoker in a pub had a drink spilled on him.....The helpful licensee produced a bottle of said cleaner and proceeded to clean the customer's clothing with it....the man was smoking and the fumes were drawn through the cigarette...he dropped dead. That precipitated the ban.
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By Paul_Sengupta
#1712207
cockney steve wrote:Dabitoff home "dry- cleaning" products


Hmm, used to use that a lot in the '70s and '80s. Possibly still got some hidden away in the back of the cupboard...
By riverrock
#1712208
I qualified as a ship based (not navy) firefighter in 2002 but Halon was already banned then so wasn't part of our practical training (ship I worked on also didn't have any BCF / Halon extinguishers).

All the literature says Halon smoke has been shown to be considerably safer than "normal" smoke. Hydrogen Bromide and Hydrogen Fluoride can be produced in small quantities which aren't nice (at all) but the original smoke is still much worse.
Halon itself is pretty safe in the quantities required to put out fire.
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By Muzzlehatch
#1712275
Halon/BCF was by far the most efficient and safe in confined spaces extinguisher but has been banned for general use extinguishers world wide in 1993 as part of the ban on CFC's which were depleting the ozone layer. BUT there are exceptions where no other practical extinguisher exists. In practice that means in aircraft, the military and in tunnels (the channel tunnel has a Halon System). Although classed as toxic, it is a very low level of toxicity, less than CO2 and it puts out fire by chemical reaction rather than by blanketing or cooling which most other systems use. A fortune has been spent since 1993 trying to find an extinguishant as safe and effective as Halon but none has yet been found although they are getting closer. Get on any airliner and look at the onboard hand held extinguishers, almost certainly they will be Halon. It's illegal to sell Halon/BCF extinguishers in Europe and most of the rest of the world to individuals other than for aircraft use. (In most of Europe excluding the UK its illegal to use a Halon/BCF extinguisher other than in an aircraft even if you have one!)
When rallying in the late 80's when Halon extinguishers we compulsory equipment, we had the halon extinguisher accidentally go off inside the car. Other than a couple of seconds confusion whilst we worked out what had happened, it didn't affect us at all and we just carried on. I can't remember any noticeable effects on our performance.
For more authoritative aircraft related info see https://www.skybrary.aero/index.php/Halon_Fire_Extinguishers
By riverrock
#1712281
Muzzlehatch wrote: It's illegal to sell Halon/BCF extinguishers in Europe and most of the rest of the world to individuals other than for aircraft use.
and the other "critical" applications - which are mainly built into the infrastructure of large industrial / petrochemical plants and military installations (including ships).
In the UK, my understanding is that there is no compunction to change a system from Halon, but new installations wouldn't be approved (and as new Halon hasn't been produced for the Fire protection industry since 2004 - all Halon available is recycled so prices will go up as supply runs out).