OK, my mistake was that I read this on wikipedia: "
Liquid carbon dioxide forms only at
pressures above 5.1
atm,.." but they are talking about dry ice changing to liquid.
Thanks for the correction. If the on-boad electronics can keep the CO2 warm then it should work down to 1600 feet.
The really good news is that 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 will produce: 20 oz * 553 = 11060 ounces or / 957.5 oz per cubic feet = 11.55 cubic feet. Very good compared to the 3 cubic feet contained inside a "spare air" bottle that is about the same size. And there is a huge and low cost selection of tanks, valves and gauges for CO2 thanks to paintball.
An excellent layman's explanation of CO2 from warpig including a Pressure/Volume diagram. This also explains why we could get some really big whelps from playing paintball as the afternoon temps increased and nobody bothered to cron their gun :)
You will need to keep in mind the orientation of the tank. You do not want the liquid to enter the valve or line because it will quickly ice up. Another valuable and paintball lesson :)
--Doug J
In a message dated 10/17/2006 3:42:53 PM Central Daylight Time, gslaterp@hotmail.com writes:
Co2 Liquifies at about 750psi at room temperature
Temperature being the biggest variant the lower the temp the lower the pressure.
----- Original Message -----
Sent: Tuesday, October 17, 2006 4:17 PM
Subject: Re: [PSUBS-MAILIST] Pressure compensation - CO2 vs Air
I think at room temp CO2 goes liquid at close to 60 atmospheres. 60 bar actually which is pretty close to 60 atmospheres.
I'd just read something interesting about it, in that it gives a pretty constant pressure out of a bottle while discharging most of its volume. The bulk of the CO2 stays liquid and just vaporizes as it's valved off - so the pressure ends up staying at 60bar. I don't know if that's true but it seems to make sense.
Paul
On 10/17/06, DJACKSON99@aol.com <DJACKSON99@aol.com > wrote:
Dean
It's more of a question than advise. If CO2 will work at 5 atm, someone on this list will hopefully correct me.
Thanks --Doug J
In a message dated 10/17/2006 1:34:48 PM Central Daylight Time,
Recon1st@aol.com writes:
to a liquid at just over 5 atm
Doug great info. Ya just saved me time investigating the issue. I new it
remained liquid at a fairly low pressure but did not think it was that low.
I do plan on making 300 to 400 foot working depth.
Nitrogen sounds good and maybe argon, quite a ways to that stage but
for right now I know I want the volume of this pressurized area to be minimal
Dean