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CO2 Gauge?

Posted: Thu Jan 01, 2009 2:25 pm
by SP00K
I'm building a burst disk cannon where the disk is to be punctured instead of broken by air pressure. I was wondering if there's a special co2 pressure gauge. I took off the pressure gauge from my foot pump (which measures up to 200 psi).

I'm not sure it I should get a special kind of co2 pressure gauge or just use the one of the foot pump of go out and buy a new pressure gauge.

Topic title edited for lack of description.

MrC

Posted: Thu Jan 01, 2009 2:34 pm
by DR
Once again, I'm left wondering how (exactly) you intend to set up your charging system. - The pressure inside of a full CO2 bottle exceeds 800psi, so a 200psi gauge off of a 5 dollar foot pump, just won't cut the mustard.

Posted: Thu Jan 01, 2009 2:48 pm
by jonnyboy
Unless you have a regulator and then the gauge your out of luck.Co2 is over 900 psi so a 200 psi gauge will just max out.

Posted: Thu Jan 01, 2009 2:52 pm
by SP00K
That's 900 psi in a small 12 gram cylinder. My cannon is about three and a half feet of 3 inch pipe. I'm gonna be using a co2 inflator and using a gauge to check when I need to stop filling.

Posted: Thu Jan 01, 2009 2:54 pm
by skyjive
You don't need specific gauges for different gas types, but people are right that unregged co2 pressure is much higher than 200 psi. If you have a regulator or are using co2 cartridges that can be fed into a large chamber to lower their pressure than this 200 gauge should, in theory, be fine, but otherwise you're out of luck.

Posted: Thu Jan 01, 2009 2:59 pm
by john bunsenburner
i seriously doubt that a normal hand pump reg wont blow up under such pressures, jsut buy the normal kind nd be safe.

Posted: Thu Jan 01, 2009 3:22 pm
by jonnyboy
john bunsenburner wrote:i seriously doubt that a normal hand pump reg wont blow up under such pressures, jsut buy the normal kind nd be safe.
He's talking about a gauge from a bike pump.

@OP

You should be fine if your filling a large chamber. Although something that small is not going to fill something that big to a respectable pressure.

Posted: Thu Jan 01, 2009 5:10 pm
by Gippeto
You'll be fine with the gauge off of your pump, filling as you describe.

There are specific gauges for specific reactive gases (O2 for example), but that has more to do with the medium used for calibration than anything else. (You DON"T calibrate a gauge using oil and then put it on an O2 service.)

With inert gases, there is no problem as long as you are not over ranging the gauge.

Posted: Thu Jan 01, 2009 5:10 pm
by frankrede
john bunsenburner wrote:i seriously doubt that a normal hand pump reg wont blow up under such pressures, jsut buy the normal kind nd be safe.
A normal hand pump doesn't have a regulator...if you mean a gauge, then the gauge is made the same way a store bought gauge is.

Posted: Thu Jan 01, 2009 5:30 pm
by john bunsenburner
yes but it is not build to hold pressures like the ones from a CO2 Bulk.

Posted: Thu Jan 01, 2009 6:05 pm
by frankrede
john bunsenburner wrote:yes but it is not build to hold pressures like the ones from a CO2 Bulk.
He's not using co2 from a large canister.Even if he were, he would have a regulator.

Posted: Thu Jan 01, 2009 6:17 pm
by jonnyboy
The gauge will be on the chamber so the pressure should be below 200 psi.

Posted: Thu Jan 01, 2009 8:21 pm
by SP00K
Yeah, I'm making a coax and I have done the math. I'm only looking to get the thing filled up to about 100 psi max.

I thought about every zspect concerning gases. All I wanted to know was whether or not I would need a spcial kind of gauge for co2, and that question was answered. Thnx gippeto

Posted: Thu Jan 01, 2009 9:29 pm
by ThumbzUpTheoden
Co2 in a 12 gram cylinder is NOT even close to 900psi. What are you guys smoking??? Even the paintball cylinders are well below that.

Edit by MrC: After a few hateful emails from this guy, he has finally acknowledged he is wrong. Apparently he made the above claim on a whim with no evidence or knowledge of any kind backing up his statement.

Posted: Thu Jan 01, 2009 9:30 pm
by MrCrowley
ThumbzUpTheoden wrote:Co2 in a 12 gram cylinder is NOT even close to 900psi. What are you guys smoking??? Even the paintball cylinders are well below that.
You do realise the pressure of CO2 fluctuates depending on the temperature, right?

BTW, just looked it up and CO2 seems to be around 860PSI at 72* F, at 80* F, it rises to 970PSI. :roll: