Pierre: Do you guys play in the winter? I can't imagine what a hand
or head shot would feel like when your skin is half
frozen!
I like the idea of
CO2. Freezing is only a problem if you were to use a
buch all at once and then close the valve. Even then, you are not going to be using the same type of valve that we use on
paintball guns. The bottom line is you will get a more blow volume, although not much more if my
calculations below are right, for the same storage capacity. Jay makes a good point about breathable air but it could make the difference as to weather you surface or sit on the bottom too. You would also want all of the valves and lines exterior the hull so you have no chance of breathing it.
CO2 Liquefies at about 750psi at room
temperature, so as long as the cylinder has some liquid in it and it is kept
warm, it will have about 750 psi. 750 psi / 15psi (1 atm) = 50 atm - 1
atm for sea-level = 49 atm * 33 feet = 1617 feet max operating depth.
A "full" tank contains about 34% liquid CO2. If it is filled any
more, the CO2 will become very sensitive to temperature changes, with a small
increase in temperature causing a large increase in pressure. This is a
dangerous situation which is avoided by only partially filling the CO2 bottle.
|
Bottle Volumes:
|
Bottle size (oz)
|
Volume (cu in)
|
|
3.5
|
9.0
|
|
7.0
|
18.0
|
|
12.0
|
31.0
|
|
20.0
|
51.0
|
|
CO2 liquid to gas expansion ratio is 1:553 according to
www.chemistry.ohio-state.edu/ehs/handbook/gases/cryosafe.htm
So a 20 ounce CO2
paintball tank has a volume of 51 cubic inches * 37%
full-fill = 18.8 cubic inches of liquid * 1:553 expansion ratio = 10435 cubic
inches of gas / 1728 cubic inches per cubic feet = 6 cubic feet of gas.
I think that at low temperature liquid CO2 doesn't work...
That is why we can't do paintball here in cold canadain winter.
Pierre
----- Original Message -----
Sent: Saturday, February 24, 2007 1:01
PM
Subject: Re: [PSUBS-MAILIST] on-board
air.
Hi Guys. Has anyone considered using compressed CO2 for blowing ballast?
It seems to me that a liquid CO2 tank would have a lot more volume than an air
tank.Frank D.
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