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Posted: Tue Feb 12, 2008 8:37 am
by psycix
paaiyan wrote:Steel wool catch on fire...

Right...

I don't believe I've ever seen steel catch fire.
:)
"How to start a Fire with Steel Wool and a Battery"
[youtube][/youtube]

Posted: Tue Feb 12, 2008 12:46 pm
by jimmy101
paaiyan wrote:Steel wool catch on fire...

Right...

I don't believe I've ever seen steel catch fire.
Yes, actually you have seen steel wool on fire... its called "rusting".

If you want to see steel wool burn more vigorously then light a piece with a match or torch. It does burn. Watch it closely and you'll see that it is not just melting, it is burning. You can remove the heat source and it will continue to burn for a short time.

Light a wad of steel wool and drop it in a jar of pure oxygen gas and the steel will burn almost instantly and give off a very bright flash of light.

Steel wool burring in a jar of oxygen;
Image
from here

Bottom line, steel (iron), copper, aluminum etc. all burn. Usually it is a very slow process (rusting), but given the right conditions most metals will burn vigorously.

Using steel wool in an oxygen + hydrogen torch as a "anti-flame-suck-back" device is probably not a good idea. In a pure oxygen environment the steel wool will burn vigorously (and explosively if it is confined) if there is an ignition source. Glass wool might be a better idea. Best of all would be a water trap or bubbler.

Posted: Tue Feb 12, 2008 12:47 pm
by paaiyan
They make glass wool?

Posted: Tue Feb 12, 2008 1:34 pm
by jimmy101
paaiyan wrote:They make glass wool?
Fiberglass

Most chemistry labs have a supply of glass wool. It is used as a filter and as a support for solids in systems that have fluids running through them.

Posted: Tue Feb 12, 2008 4:00 pm
by psycix
jimmy101 wrote: Using steel wool in an oxygen + hydrogen torch as a "anti-flame-suck-back" device is probably not a good idea. In a pure oxygen environment the steel wool will burn vigorously (and explosively if it is confined) if there is an ignition source. Glass wool might be a better idea. Best of all would be a water trap or bubbler.
Yup, using steel wool as anti-flame-suck-back system is only suited for people who have a strong wish to die.

I wouldnt do glass wool, the burning speed (well, burning?, more like exploding) of an H2 + O2 mixture is extremely high and poweful.
I think that there are chances that your flame will get trough the wool.

Use a bubbler, maybe even two of em and MAKE 100% sure it works fine.
Or (as I would do) separate the H2 and the O2 during the electrolysis and mix em at the nozzle.

Mistakes with hydrogen tanks and suckbackflames are only made once in a lifetime, at the end of a life that is.

Posted: Tue Feb 12, 2008 10:00 pm
by rp181
For example:

I was doing electrolysis a while ago, it was a glass jar with a metal lid, and a heavy brass T haappen to be sitting on it. I lit the gas, there was a big boom and the T flew across the room. The lid was deformed beyond repair.

Do a bubbler or two. Easy and cheap.
Mabey a oneway valve?

Posted: Wed Feb 13, 2008 9:21 am
by psycix
I think that a oneway valve isnt fast enough to stop the flames and secondly:
Will it hold the enormous shockwave of exploding H2+O2?

Posted: Wed Feb 13, 2008 10:31 am
by rp181
i think it might stand a chance, with the small dia. tube. For a hho torch, people use ball needle as the tip. They have bubblers and a chamber with a porous material in it, whats it for? Its right before nozzle, ive seen bronze wool, porous plastic and cotton. If you stuffed a bottle with cotton so the hydrogen and oxygen would have to force through, i think it could prevent or even slow a blowback.

Posted: Wed Feb 13, 2008 11:48 am
by jimmy101
rp181 wrote:i think it might stand a chance, with the small dia. tube. For a hho torch, people use ball needle as the tip. They have bubblers and a chamber with a porous material in it, whats it for? Its right before nozzle, ive seen bronze wool, porous plastic and cotton. If you stuffed a bottle with cotton so the hydrogen and oxygen would have to force through, i think it could prevent or even slow a blowback.
Blowback that reached a cotton filled chamber containg pure oxygen would be a grenade.

Anything used to stop blowback really should be non-flammable and have as a high a heat capacity as possible.

In this application, steel wool would be considered flammable. Glass is the only thing I can think of that is sufficiently non-flammable in pure O<sub>2</sub>.

Posted: Thu Feb 14, 2008 6:59 am
by psycix
Indeed, just do a two bubblers and no other stupid things that cant be trusted.