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Checking how full a gas bottle is?
locoboy - 12/7/07 at 10:20 AM

I have stumbled accross 2 W size bottles of Argoshield Heavy at work, one with a regulator on it and the one dial is reading 0.35 bar.

Does this determine how full it is?

If so what is 'full' pressure?

If not when how do i find out how full they are?

tks - 12/7/07 at 10:48 AM

It will depend on the size.

If you would read 0 bar then there would be 20liters left, but because of the fact that it won't come out!
you could say its empty..

sow 0,35Bar is empty..

200Bar = Full for a big size cilinder.

dunno the W types...

Hope it makes sense...
also the pressure rise isn't constant with the volume of gas in the bottle sow twice the pressure isn't twice the volume.
in the end every drop of gas more will raise allot of pressure..

Tks

asn163 - 12/7/07 at 11:45 AM

Hi,

As stated above, usual fill pressure will be 200 bar.

0.35 bar would be empty, the cylinder is probably fitted with a residual pressure valve to maintain a slight positive pressure to prevent ingress of water etc. when "empty".

Simon

Confused but excited. - 12/7/07 at 03:38 PM

quote:
Originally posted by tks

also the pressure rise isn't constant with the volume of gas in the bottle sow twice the pressure isn't twice the volume.
in the end every drop of gas more will raise allot of pressure..

Tks


Wrong!
If the tempurature is constant (isothermal compression), then twice the pressure does equal twice the volume.
Basic schoolboy physics.....
If you compress a volume of gas quickly to half it's volume then the pressure will more than double, this is because of the rapid compression raising the energy level of the gas. This is called adiabatic compression. It will however stabilse at twice the original pressure when it cools back down to the original gas temperature.

lsdweb - 12/7/07 at 04:18 PM

quote:

If not when how do i find out how full they are?


Easy. Open the valve and listen to the hissing. When the hssing stops you know how full it is (isn't!) Sorry - stupid reply!

NS Dev - 19/7/07 at 12:41 PM

.....................and all of this depends on the gas of course!!

If it is a compressed gas in there then all that holds true, but if you were talking about CO2, then that is a liquid in its bottle, and the pressure stays constant (vapour pressure) until all the liquid has vapourised, then it starts to drop.

Peteff - 19/7/07 at 01:10 PM

there's loads in it