SpudFiles

It's getting colder (mid 40's F) around here now, and I like to shoot my ABS combustion gun in the winter. Snowballs and such...
At 40F, it takes the propane about a minute and a half to get up to 70psi (my meter pressure).

I'm wondering about wrapping nichrome wire (such as the wire heating element in cheap electric toasters) around the propane tank, connected to a 12v lantern battery with a variable resistor (dimmer) to bring the propane tank up to, say 75F. At that temperature, the meter pipe gets up to pressure much quicker.

The problems I see are:
You can't simply wrap the tank with nichrome wire, because then the 12v current would pass through the tank instead of the heating wire. So something will have to be used for electrical insulation between the wire and the tank.
Something will also have to be used to insulate the 3" pipe I use to hold the propane tank, from the heat of the wire. A layer of thick canvas maybe?
Providing a powerful enough electric source to be mounted on the gun may be a slight issue.

Is it a stupid idea to start with, or can it be done?

Just throwing one out there.

Peace,
Pete Zaria.

I wouldn't risk it. a spark, a fume, and BOOM! the tank's exploded, and your head is separated from your body. just wait the minute and a half.

hey I saw a tank warmer for co2 tanks at wal-mart, why dont you try one of those? im assuming you use the blue 400 gm. bernzomatic tanks

Heard of enamelled wire?

Its whats used on coil windings for transformers and motors, the insulation's enough to stop a few KV while only being a few micrometers thick.


I'd rather not do it though.

lol why would they sell co2 tank warmers co2 the colder the better for co2. but I would just wrap some duct tape or something around the tank then use the toaster stuff then some insulation around that.

no, warmer co2 = higher pressure, rapidly discharging a pressurized tank will cool it down and possibly freeze it. That makes the pressure lower and you dont want the pressure to drop off.

schmanman wrote:I wouldn't risk it. a spark, a fume, and BOOM! the tank's exploded, and your head is separated from your body. just wait the minute and a half.

There's no oxygen in a propane tank. A spark couldn't ignite it. You'd have to get the bottle amazingly hot to "detonate" it.

nicholai wrote:hey I saw a tank warmer for co2 tanks at wal-mart, why dont you try one of those? im assuming you use the blue 400 gm. bernzomatic tanks

Link please?

Hotwired wrote:Heard of enamelled wire?

Its whats used on coil windings for transformers and motors, the insulation's enough to stop a few KV while only being a few micrometers thick.
I'd rather not do it though.

Yes, but how well does the enameled wire transfer heat? Could it take the heat the nichrome produces without melting? I'm looking for something like a thin sheet of asbestos, but much less carcinogenic/cancerous.

Thanks for the input, guys.

Peace,
Pete Zaria.

I'd personally try using half the meter pressure and injecting two lots of propane. You should get enough pressure from the tank to manage that.

It's barely any more trouble, and doesn't cost you anything.

Run the pressure much lower such as 30psi and have to shots of propane instead of one to get to the 4.03% mixture it would work and its easy.

^ Beat you to that one!

But no matter - at least it confirms the idea.

DAMN!..Touche! good chap,looks like were kinda on the same level.

Pete Zaria wrote:

schmanman wrote:I wouldn't risk it. a spark, a fume, and BOOM! the tank's exploded, and your head is separated from your body. just wait the minute and a half.

There's no oxygen in a propane tank. A spark couldn't ignite it. You'd have to get the bottle amazingly hot to "detonate"

I said a fume, I ment from the tank. I never said anywhere that I ment the tank itself.

So what? How do you expect that to travel back into and detonate the tank when it contains no oxygen.

I don't think he expects it to detonate the tank, but you don't want random explosions or flames near your launcher.

Propane and electricity don't mix.

I already do two shots at 70psi :-p It'd take 4 shots at 35psi. My chamber volume is 250ci, it takes a fair bit of propane.

I'm going to try duct taping a layer of thick canvas or denim around the tank, then wrapping with a loose spiral of nichrome wire connected to a 12v lantern battery with a dimmer. I'll test to find a setting that will get the propane warm (around 75 or 80F) but below 100 (don't want to over pressurize it). I'll let you know how it goes.

Peace,
Pete Zaria.