Co2 for PCP, may have a solution?

[Shuck.]

I have no experience at all with PCP rifles but does anyone do any homebrew here? Can you see where I'm going? Is it a stupid idea to use the fermentation process to full up your tank?

Mods if this is a stupid idea please spare me the embarrassment and delete this thread

[MM]

And you have been smoking what exactly?

[Billy.]

I can't quite see liquid carbon dioxide being made by the fermentation of fruit, alcohol or anything else for that matter in a confined space.

 

If you did attempt it, you'd be lucky to get above 1 bar. 231 left to go...

[Shuck.]

You need liquid CO2? This I didn't know Worth a mention though eh... No? Oh. ok

 

It seemed flawless a minute ago... damn

[Shuck.]

How about blowing up footballs, on masse? no?

[Ozzy Fudd]

could be a use for it

[Billy.]

You need liquid CO2? This I didn't know Worth a mention though eh... No? Oh. ok

 

It seemed flawless a minute ago... damn

 

Compressed CO2 is always in liquid form in gas canisters. It's the same as lighter fluid, you always see that as a liquid, but when it depressurises it turns to a gas. Something to do with very cold gases remaining a liquid if kept under pressure.

 

Anyway, PCP airguns use oxygen/nitrogen mix. So it might be worth taking a load of green plants, shoving them in a pipe, sealing it and wait for your free air... Or go to your local diving shop/firestation (Tight bastar.....)

Edited August 10, 2009 by harfordwmj

[casts_by_fly]

Compressed CO2 is always in liquid form in gas canisters. It's the same as lighter fluid, you always see that as a liquid, but when it depressurises it turns to a gas. Something to do with very cold gases remaining a liquid if kept under pressure.

 

Anyway, PCP airguns use oxygen/nitrogen mix. So it might be worth taking a load of green plants, shoving them in a pipe, sealing it and wait for your free air... Or go to your local diving shop/firestation (Tight bastar.....)

 

 

 

Actually, CO2 is rarely a liquid when it is bottled up. CO2 does not liquify easily at all, in fact liquid carbon dioxide is considered supercritical because it is outside of its normal thermodynamic properties as a liquid. CO2 behaves like an ideal gas, and ideal gasses don't liquify. At standard atmospheric conditions, CO2 goes gas to solid (and back) and completely skips the liquid phase (sublimination). In a tank/bottle/canister CO2 is compressed to very high pressures so that you can get more molecules into the bottle and thus go longer without refilling.

 

The difference with lighter fuel is that butane and other hydrocarbons have a boiling point just a bit below ambient temperature and a vapor pressure that isn't terribly high. That means that you can compress them a little (3-8 barr for lighter fluid mixtures) and they turn liquid. It also means that as long as you have the smallest amount of liquid in your container the pressure will be at the vapor pressure of that mix. Doesn't matter if you have 1 gram or 100 grams of liquid, the pressure is the same. In theory, if you had a mixture that provided the same pressure as you needed in the rifle, you could get one fill of that mixture and it would las a lot longer than CO2 of the same fill. It would also give a constant pressure output for 99% of the bottle. At the same time though you'd be hauling around a bomb that if it ever leaked could blow up on you as soon as it hit an ignition source (hope you don't smoke).

 

Thanks,

Rick

[Billy.]

Actually, CO2 is rarely a liquid when it is bottled up. CO2 does not liquify easily at all, in fact liquid carbon dioxide is considered supercritical because it is outside of its normal thermodynamic properties as a liquid. CO2 behaves like an ideal gas, and ideal gasses don't liquify. At standard atmospheric conditions, CO2 goes gas to solid (and back) and completely skips the liquid phase (sublimination). In a tank/bottle/canister CO2 is compressed to very high pressures so that you can get more molecules into the bottle and thus go longer without refilling.

 

The difference with lighter fuel is that butane and other hydrocarbons have a boiling point just a bit below ambient temperature and a vapor pressure that isn't terribly high. That means that you can compress them a little (3-8 barr for lighter fluid mixtures) and they turn liquid. It also means that as long as you have the smallest amount of liquid in your container the pressure will be at the vapor pressure of that mix. Doesn't matter if you have 1 gram or 100 grams of liquid, the pressure is the same. In theory, if you had a mixture that provided the same pressure as you needed in the rifle, you could get one fill of that mixture and it would las a lot longer than CO2 of the same fill. It would also give a constant pressure output for 99% of the bottle. At the same time though you'd be hauling around a bomb that if it ever leaked could blow up on you as soon as it hit an ignition source (hope you don't smoke).

 

Thanks,

Rick

 

that was what I meant to say

[Shuck.]

Compressed CO2 is always in liquid form in gas canisters. It's the same as lighter fluid, you always see that as a liquid, but when it depressurises it turns to a gas. Something to do with very cold gases remaining a liquid if kept under pressure.

So you're saying you can't use CO2 at all even if it's at the right temperature because of its physical storing state?

I was thinking along the lines of those industrial strength cylinders originally made for conditioning Coke

 

... Or go to your local diving shop/firestation (Tight bastar.....)

 

Edited August 11, 2009 by Shuck.