Sciencemadness Discussion Board

Is compressed oxygen in a cylinder a supercritical fluid ?

metalresearcher - 4-10-2023 at 07:52

A supercritical fluid is a substance over its critical temperature and its critical pressure. So water above 221 bar and 374 C is critical. So is CO2 on Venus (93 bar and 460 C) and even hydrocarbons on Jupiter and Saturn.
O2 has a critical point of -118 C and 50 bar which means that these cylinders have a supercritical content as these are 200+ bar and room temperature. Even the single use small 90 bar cylinders are supercritical.
Is my assumption true ?

Tsjerk - 4-10-2023 at 11:11

Do they contain liquid? Isn't it just compressed?

DraconicAcid - 4-10-2023 at 11:33

Quote: Originally posted by Tsjerk  
Do they contain liquid? Isn't it just compressed?

You can't liquify a gas above its critical temperature.

j_sum1 - 4-10-2023 at 17:12

If your data is correct, then yes. It is supercritical.

unionised - 5-10-2023 at 04:47

It is; indeed compressed air is often supercritical.

Morgan - 5-10-2023 at 09:49

Tidbit
"Instead of having to install protection for circuit breakers, the high pressure can be turned to our advantage. High pressure on the sea floor, combined with the low critical temperature of nitrogen, means that nitrogen is supercritical under sea floor conditions!"
https://blog.sintef.com/sintefenergy/supercritical-nitrogen/