Forums > Technical Discussion > chemicals to extinguish fire props during a performance

Posted: 26th Mar 2008
Sometimes when its very misty/cold/humid fire poi burn all the available oxygen in the air immediately around them and spontaneously go out.

If you could recreate this effect with some consistency it might be what your looking for. I guess something like a container of dry ice might work if the air was still enough and you got a large enough area of 02-less air around the container. I suspect it might be difficult to do it with consistency though. Failing that a box filled with CO2 from a canister would work, although wouldnt recreate your desired effect of waving the poi over a container and them going out.

GL keep us posted

Posted: 26th Mar 2008
As many have said, i think dry ice will be your best substance. On another note, you may want to try getting a metal bax with a nice lid that you can toss yer toys into and close to get them to go out.

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Posted: 26th Mar 2008
Well...there is a gas which eats oxygen, it's what they use in labs/offices where they can't have sprinklers - but I doubt it's readily available as it tends to make people die from suffocation...
Can't remember the name of it either - haly-something?

You basically need a way to starve the props of oxygen safely - water isn't suitable as it'll mess your wicks about, fuel (paraffin or less-volatile fuels) do work but there's just no way you'd get it past a health and safety check. Plus, if you don't smother the wick you're gonna be in trouble
If you're quick - a quick water dunk mightn't be too bad, as residual heat would steam some of it out and you won't be leaving it in the water. If there's enough fuel left on the wick it will help to repel the water and stop it seaping further into the wick.

Hrrrm... I'm not sure about dry-ice. Isn't it liquid hydrogen? How flammable is hydrogen once it's up to temperature?

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Posted: 27th Mar 2008
Dry ice is frozen CO2 and is perfectly safe providing you dont handle it (its pretty cold). The idea would be not to place the wicks direcly into the dry ice but to starve the wicks of oxygen, thus the actual extremes of temperature wouldnt be that high, providing you could create a large enough O2-less area around the wicks for it to work. Same principle as the box of CO2 gas, which is pretty easy to get hold of too (soda stream canisters or fire extinguishers - though of couse not the same one your using as safety). Any other inert gas would also work, e.g. nitrogen but would be more difficult to get hold of. liquid nitrogen would be too dangerous, dont even go there (its way too cold and can cause burns -200C or so).



Durbs, hydrogen is indeed a very bad idea, the Hindenburg was filled with hydrogen...
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Posted: 27th Mar 2008

 Written by :Durbs


Well...there is a gas which eats oxygen, it's what they use in labs/offices where they can't have sprinklers - but I doubt it's readily available as it tends to make people die from suffocation...
Can't remember the name of it either - haly-something?

I think you mean Halon, its not used much anymore I dont think because it depletes ozone.

Posted: 28th Mar 2008
Dry ice in a container is definitely the way to go. It'll fill the airspace in the container with carbon dioxide, no oxygen so the flame should go out straight away. And it's only gas, so it won't cool your kit down that rapidly.

It's pretty safe stuff unless you hold it against your flesh for a while. I've been putting it in drinks for that bubbling mist effect for years.

Posted: 6th Apr 2008
The dry ice bucket sounds like a good idea. We used a CO2 fire extinguiser for a little while for the same reason (to try and speed up prop swaps) but found that a fire safety officer who knows whats going on is much more practical.

A fire safety can take your lit prop off you and hand you the next one already lit so the only time it takes to switch is walking to the back of the stage. Plus the obvious safety advantages of having someone watching your back while you are performing.

"Don't do it naked!"

Posted: 11th Apr 2008
You could always try argon, its readily available as it's used in welding, i use the stuff every day. The glory of argon, is that it's inert and heavier than air, so if you were to fill a container full of it, it should stay put for a fair while, and not just float off.

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Posted: 11th Apr 2008
If my chemistry is right and its been a few years, any of the group 18 elements would suffice... the further down the group you go the more unstable/expensive they become.

You could even use helium but its lighter than air so would disperse unless you inverted the bucket over your head, filled it with helium and did a stall into the bucket to put them out! Helium also has a bad reputation when it comes to fire (Hindenburg!) although some chemists would argue that point!

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Posted: 11th Apr 2008
Durbs, I think you mean Halon. It's featured in Terminator 2 when they are in the cyberdyne office, and they say films don't teach you anything

Could somebody stop the room please... I'd like to get off