New gas setup problem (Newbie)

[JA3llis]

Hi all right just bought my pub gas setup of my tool man. It included new gauges twin dial co2 ones made by parweld piping and a pub gas bottle. I rigged all the gauges up (Not to my welder has it hasnt arrived yet) So I loosend the large knob on the gauges and cranked the bottle knob on full. Now either I am daft or the bottle or gauges are faulty. On the gauges one reads bottle pressure the other reads lpm. The bottle pressure reads only just off the stop! and this is ment to be full if i open the gauge valve c02 comes rushing out. Am I doing something wrong or is the bottle nearly empty I have tried blanking the end of the pipe off and the lpm reads fine but the bottle pressure is still only just reading on the scale.

Many thanks

 

[wyn]

With gauges you need to tighten the knob on them inwards/clockwise to increase the flow out of them.

 

[pedrobedro]

CO2 doesn't show much pressure in the cylinder as it is stored as liquid and only the top is gas as the liquid vapourises. They are usually filled by weight not pressure.

 

[voipio]

In a filled pub gas cylinder, most of the gas will be in the liquid state. The vapour pressure of liquid CO2, and thus cylinder pressure, is around 60 atmospheres (900psi) at 22 degC, 40 atmospheres (600psi) at 6 degC and 20 atmospheres (300psi) at minus 19 degC. The pressure in the cylinder will remain close to this temp vs pressure curve until all of the liquid has evaporated as the contents of the cylinder are released. Beyond this point, the cylinder pressure will fall as the last of it's contents are exhausted. The way to measure the contents of a pub gas CO2 cylinder is to weigh it and subtract from that weight the tare weight stamped on the cylinder. If the cylinder has been stored outside, with the current cold weather, the cylinder pressure will be low. A lot of gauges seem to underestimate cylinder pressure anyway, so your observations are not really surprising. If you brought the cylinder indoors and allowed it to warm up fully, and the gauge reading increased by little or not at all when the cylinder reached room temperature, it is likely the cylinder is nearly empty.

 

[JA3llis]

I have bought the cylinder indoors from my workshop which is reading -12 atm. I will report my findings tomorrow many thanks for all the help

 

[slimjim]

In a filled pub gas cylinder, most of the gas will be in the liquid state. The vapour pressure of liquid CO2, and thus cylinder pressure, is around 60 atmospheres (900psi) at 22 degC, 40 atmospheres (600psi) at 6 degC and 20 atmospheres (300psi) at minus 19 degC. The pressure in the cylinder will remain close to this temp vs pressure curve until all of the liquid has evaporated as the contents of the cylinder are released. Beyond this point, the cylinder pressure will fall as the last of it's contents are exhausted. The way to measure the contents of a pub gas CO2 cylinder is to weigh it and subtract from that weight the tare weight stamped on the cylinder. If the cylinder has been stored outside, with the current cold weather, the cylinder pressure will be low. A lot of gauges seem to underestimate cylinder pressure anyway, so your observations are not really surprising. If you brought the cylinder indoors and allowed it to warm up fully, and the gauge reading increased by little or not at all when the cylinder reached room temperature, it is likely the cylinder is nearly empty.

I never new that, my CO2 guage never had a cylinder pressure guage, I just used it untill it ran out, then I changed it!