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I got a small, portable, propane tank for my bbmg. I just attached it directly to the gun. and it was working BUT it was so cold it was freezing up the gun. the hoses and everything started frosting over. do you think I need a regulator?

Nope.

A regulator really won't do much unless you regulate the pressure way down to say 50 PSI or less.

boom_o_matic_2.0 wrote:I got a small, portable, propane tank for my bbmg. I just attached it directly to the gun. and it was working BUT it was so cold it was freezing up the gun. the hoses and everything started frosting over. do you think I need a regulator?

Propane under pressure in a bottle is a liquid. It takes heat to boil it. If you take liquid out of the bottle and drop the pressure, it will boil cooling the surfaces, which is why you got frosty gun and hoses. Keep the tank upright so the liquid stays in the bottle. Let it boil in the bottle, not the gun. As you use gas, the bottle will cool just the same as CO2

A regulator won't change the fact propane will evaporate to turn to a gas and this takes heat away making things colder.

You could try to use some sort of heatsink-ed (cold-sink) expansion chamber between the tank and the gun. The propane will boill off and expand in this chamber, and the heatsink will warm it up, taking heat from the environment.
For continuous firing, you will need a large heatsink though.

Another thing is to fire in bursts and taking it easy instead of emptying the whole mag in one go - reload - empty again - and so on.

There's no need to regulate propane- at standard temperatures the pressure is near ideal.

The perfect gas law states that as a gas expands it will cool. As propane is stored as a liquid this is greatly exaggerated. CO2 also has the same problem. Gasses that are not liquefied handle tasks a lot better than this.



Good luck

Edit: try a thermostat (or heat source). For an improvised bbmg I used ages ago (and is now non-existant) I wrapped a hot bean/water bag around it for moar.

inonickname wrote:There's no need to regulate propane- at standard temperatures the pressure is near ideal.

The perfect gas law states that as a gas expands it will cool. As propane is stored as a liquid this is greatly exaggerated. CO2 also has the same problem. Gasses that are not liquefied handle tasks a lot better than this.



Good luck

Edit: try a thermostat (or heat source). For an improvised bbmg I used ages ago (and is now non-existant) I wrapped a hot bean/water bag around it for moar.

For high volume an old air conditioner coil can take liquid propane and convert it while keeping the bottle and system pressure up.

Gas engines (not the little ones) use the engine cooling water to heat a "vaporizer" to boil the liquid.
http://www.altenergy.com/2006/Vaporizers.htm
You don't need anything that big so building your own to be even a coil of copper tube in a cooler filled with warm water will work. The downside is this limits mobility.

I ran the propane source (from a deoderant can, lol!) through boiling/very hot water.

This increases the vapor pressure dramatically, for moar.

I was also toying with the idea of a portable thermostats for paintball gun mounted CO2 tanks, but dropped it because:

1. I don't play paintball.

inonickname wrote:I ran the propane source (from a deoderant can, lol!) through boiling/very hot water.

You know how the can says keep below 120 degrees Fahrenheit?
that might be a good idea... that said, it didn't blow up in your face, so the safety factor might be higher than I thought...

I think that heating the propane tank with the popoff exhaust would be a good idea. (now I sound like a hypocrite ) Maybe use a ballast chamber for a sustainable flame, perhaps build an aspirated burner for it. The higher the temperature will decrease gas consumption and increase the available pressure will be. A regulator would be a good idea.

ramses wrote:

inonickname wrote:I ran the propane source (from a deoderant can, lol!) through boiling/very hot water.

You know how the can says keep below 120 degrees Fahrenheit?
that might be a good idea... that said, it didn't blow up in your face, so the safety factor might be higher than I thought...

I think that heating the propane tank with the popoff exhaust would be a good idea. (now I sound like a hypocrite ) Maybe use a ballast chamber for a sustainable flame, perhaps build an aspirated burner for it. The higher the temperature will decrease gas consumption and increase the available pressure will be. A regulator would be a good idea.

It's why I mentioned warm, not hot.

ou don't need anything that big so building your own to be even a coil of copper tube in a cooler filled with warm water will work. The downside is this limits mobility.

Maybe I should have covered this in more detail. Most propane tanks don't like the pressure of over 120 degree weather... Now that I think about it, I don't either.

I think that heating the propane tank with the popoff exhaust would be a good idea.

Make sure the pop off you use is less than the one in the propane tank.

yea I just had the tank connected directly onto the gun. and it was horozontal. thats probably my problem. I"ll just run a hose from it to the gun and try that.

Technician1002 wrote:

ramses wrote:

inonickname wrote:I ran the propane source (from a deoderant can, lol!) through boiling/very hot water.

You know how the can says keep below 120 degrees Fahrenheit?
that might be a good idea... that said, it didn't blow up in your face, so the safety factor might be higher than I thought...

I think that heating the propane tank with the popoff exhaust would be a good idea. (now I sound like a hypocrite ) Maybe use a ballast chamber for a sustainable flame, perhaps build an aspirated burner for it. The higher the temperature will decrease gas consumption and increase the available pressure will be. A regulator would be a good idea.

It's why I mentioned warm, not hot.

ou don't need anything that big so building your own to be even a coil of copper tube in a cooler filled with warm water will work. The downside is this limits mobility.

Maybe I should have covered this in more detail. Most propane tanks don't like the pressure of over 120 degree weather... Now that I think about it, I don't either.

I think that heating the propane tank with the popoff exhaust would be a good idea.

Make sure the pop off you use is less than the one in the propane tank.

The can was below 120 fahrenheit. I simply ran a tube coming from it through very hot water, though they can explode if the can gets too hot.

Note that if you fill your gun up with warm or hot propane, and it cools down, the propane will condense and become fluid again.

You really don't need hot water, you just need a large thermal mass. There are a couple fairly easy ways to do it.

Drop the propane tank in a bucket of water. Water has fairly high "thermal inertia" (heat capacity). In addition, heat transfer fairly quickly from the water. A large hunk of metal would work to but it won't transfer heat as effectively or as fast as will water.

Put a longish coil of hose between the tank and the gun. The hose has a large surface area and will absorb heat form the air fairly efficiently. This is generally called an "expansion" chamber. A coil of copper pipe would work well and hold it's shape. For more / better heat transfer put the coil in a bucket of water. Rubber pressure hose will work to but rubber doesn;t transfer heat as fast as a metal pipe will.

well today I got a hose for it. the coiled kind....and I was just gonna use it to fill up my pneumatic rifle...and it was to high pressure for the tire fill valve to stay on. =\

psycix wrote:Note that if you fill your gun up with warm or hot propane, and it cools down, the propane will condense and become fluid again.

Only down to the vapor pressure of the saturated liquid vapor. Unless you keep the cannon on ice, it should provide plenty of go. To prevent condensation, (which releases heat) stop filling when the filling warms the cannon indicating condensation.

well today I got a hose for it. the coiled kind....and I was just gonna use it to fill up my pneumatic rifle...and it was to high pressure for the tire fill valve to stay on. =\

I had the same problem and switched to quick couplers.