CO2 cylinder pressure

[Justikanz]

Ehh... I accidentally toppled the CO2 cylinder when trying to find out what is wrong with my Ehiem external filter (another thread). Upon uprighting it, I realised the pressure indicated on the regulator has increased to double the normal! It shows 100kg/cm2 (PSI?) rather than the 50kg/cm2 just before it toppled... I dun dare to on the CO2 now... Is it ok? Will the pressure drop over time or would I need to release the CO2 to relieve the pressure?

[hwchoy]

PSI = Pound per Square Inch

100 kg/cm2 = 1422 PSI which is WAY too much. and that is something not right because 1000 PSI is the vapour pressure of CO2 meaning the cylinder internal pressure should stay around 1000 PSI as long as there is liquid CO2 inside. Pressure starts dropping only after you deplete the liquified CO2.

Maybe your meter is out of calibration after being dropped?

[|squee|]

Shut off the valve and quickly bring to a industrial gas company for check up?

[Justikanz]

Would the liquid CO2 be stirred up and expanded during the topple? In that case, would it be ok to just let it sit? I can't seem to shut the main valve now... and really dun dare to turn on the needle valve to release the gas...

[hwchoy]

halamak, the liquid CO2 cannot expand one lah, remember it is in liquid form BECAUSE of the cylinder holding it in under high pressure. just make sure you don't heat the cylinder.

Just sit the cylinder upright, the liquified portion will be at the bottom. Since you can't shut the main valve then better don't remove the regulator. Better bring it for checks since the main valve is so strong and yet you can jam it, must have been a bad fall.

alternatively sacrifice the gas, bring it to somewhere open, remove the regulator and let the gas run out.

[Justikanz]

But I just toppled it over... Think I will bring it out of the flat and turn on the needle valve and hope for the best... Hopefully it is the regulator gone bonkers... Safety is more important...

[hwchoy]

don't understand what you try to imply by "but I just toppled it over…". do you mean it wasn't a bad fall, or do you mean you think the gas is still all swirled up?

*confused*

[hwchoy]

the needle valve is way too slow, the outlet pressure is only 40PSI. just open the regulator lah.

anyway the worry here is you have damaged your regulator and the pressure might be passing through to the needle valve, although very unlikely scenario.

there is NO WAY the pressure could have increased by dropping the cylinder, only way to increase pressure is to heat it.

[Justikanz]

Oops... Sorry, I meant it is not a fall, it just toppled over on the floor... Today really not my day... My filter problem still has not settle yet...

[hwchoy]

that's why I think it is the meter that is off calibration. but then you say the main valve cannot close, that sounds pretty bad.

[Justikanz]

I'm confused too... The main valve just cannot be turned... Maybe I didn't open it fully previously?...

[hwchoy]

well, can you turn it THE OTHER way?

[Justikanz]

Ok, latest report... I've tried to turn the valve in the direction to close it tight and then I opened the needle valve... The indicated pressure dropped to zero as the gas was released. I turn the main valve a little to open and the pressure indicate 1500psi again... I dun dare to open the main valve fully now...

[hwchoy]

dun worry lah, your pressure gauge screwed liao. how can an enclosed body of gas gain pressure? cannot right?

[Justikanz]

yup... The pressure in the cylinder should be maintained at an equilibrium and not higher... which was slightly more than 50kg/cm2 previously... So, the gauge must have gone bonkers after the topple...

Thanks, Choy!

[hwchoy]

besides your previous pressure (assuming your gauge not screwed to begin with) was about 700 PSI which is below CO2 vapour pressure, meaning there is NO MORE liquid CO2 inside liao lah. time to go top up.

[Justikanz]

Gee... it always show slightly more than that number when it was fully topped up... You mean the gauge was spoilt in the first place and the topple actually knocked the sense back to it??

The pressure inside a full cylinder should be more than 1000psi, eh?...

[hwchoy]

swipe this info off the net, supposed to be from a professor, but you can go verify more sources.

vapour pressure (PSI) of CO2 at given temperature (°C), this is the pressure in a cylinder WITH LIQUID CO2, doesn't matter whether full or not. I think they normally weigh the cylinder to calculate the amount of liquid CO2 rather than check the pressure (which doesn't tell you anything about the amount of liquid CO2).

0-----------------506
5-----------------576
10----------------653
15----------------738
20----------------830
25----------------933
30---------------1046

[Justikanz]

If so, then I think I just knocked the senses back to the gauge...