50cc of CO2 = 25grams of CO2?

[Effervescent]

You guys know everything: I have a Hit Air vest now and was thinking about grabbing somw extra bottles. Hit Air sells them for $15 unshipped. I think I found them shipped on ebay for $11.

 

Anyone know a reasonable distributer? Anyone know if 50cc equals 25 grams?

 

Thanks,

-Eff

[Smoky]

50cc of water at a certain temp is 50 grams.

 

50cc of what?

[SPPlueckhahn]

CO2 Carbon Dioxide:

Its density at 25 °C is 1.98 kg m-3, about 1.65 times that of air

 

according to wikipedia , but the calculation to 50cc you got to do on your own

[Boffin]

CO2 Carbon Dioxide:

Its density at 25 °C is 1.98 kg m-3, about 1.65 times that of air

 

according to wikipedia , but the calculation to 50cc you got to do on your own

 

Lets call that 2kg per cubic meter, or 2kg per 1,000 litres which is 0.002g/cc At room temperature and 1 atmosphere of pressure.

 

That means 25grammes of CO2 is 25/0.002 = 12,500 cc.

 

Boyle's Law tells us that at a fixed temperature, the product of pressure and volume of a fixed quantity of gas are a constant, or PV=K where P = pressure, V= Volume and K= the Boyle's constant for the gas.

 

So we have volume 12,500, pressure 100kpa(nominal) which gives k = 1,250,000

 

So using p2 = p1v1/v2 25g may be 50cc (V2) if the pressure (P2) of the storage vessel is 1,250,000(p1v1) / 50 = 25000kpa or 3625psi

 

 

Andy

[Effervescent]

WHAT DA!?!

 

-Eff

[Boffin]

WHAT DA!?!

 

-Eff

 

Sorry - I am an engineer after all...

 

The simple answer is that you can't compare weight and volume when dealing with pressurised gas as they vary with each other.

25g is a lot of CO2 - 12500cc at normal atmospheric pressure, so that weight may include the container. A 50cc container would be about 2 inches long by 1/2 inch diameter - which is what a soda-syphon cartridge would be.

 

HTH, Andy

[Effervescent]

Hmm...my Japanese Hit air cartridge reads 50cc and is 4 inches by 1 inch.

The closest I could find were these on ebay: 25 grams.

http://cgi.ebay.com/CO2-Re-Arming-Kits-2...tem320047900642

 

-Eff

[Redbrick]

Quote:

 

So using p2 = p1v1/v2 25g may be 50cc (V2) if the pressure (P2) of the storage vessel is 1,250,000(p1v1) / 50 = 25000kpa or 3625psi...

 

Quote:

 

Wow.......I didn't know that !!!

 

Phil.........Redbrick

[Effervescent]

I leave here with more questions than answers!

-Eff

[ESokoloff]

Eff, don't definitively know the answer to your quest but based on this you need a 30 gram cartridge. Perhaps you could "get away" with using a 38 gram cartridge as seen here but being this is a life safety item you MUST be sure of compatibility issues & unfortunately that may mean OEM.

Unless you are TESTING the vest, in theory you should not need any spare cartridges.

If you are merely testing the vest then using a smaller (25 gram)charge cartridge should not be an issue, but don't take my word for this

[ESokoloff]

I leave here with more questions than answers!

-Eff

 

Another thing.

I'm ASSUMEing that the vest is of Japanese origin & thus the cartridge threads would be metric.

[Joe Frickin' Friday]

So using p2 = p1v1/v2 25g may be 50cc (V2) if the pressure (P2) of the storage vessel is 1,250,000(p1v1) / 50 = 25000kpa or 3625psi

 

these guys claim that cannister pressure is about 850 psi. Not only that, but their P-V diagram indicates a combination of liquid and vapor will be present in the vessel; the exact quantity of liquid and vapor is going to be a function of how much mass is crammed into the cannister (as well as temperature), so overall density is going to be impossible to know without knowing the mass and volume involved. And you're after mass anyway, so once you know that, don't bother measuring volume.

 

this site lists various cartridges and weights. The weight on the main page is apparently the CO2 weight; if you click on an item, the item description lists the total item weight, which is considerably greater. The first items on the list look like the cannisters that came with my RT, i.e. about 3 inches long. Don't know how big the cannisters are that you're looking at buying, but maybe you can gauge their size by comparing with what you see on this page.