2 replies to this topic

[Hankj]

Hello,

 

We have Helium-4 at room temperature pressurized to 32,000 PSIG in a 11.9 cubic foot vessel. This is well above the critical point of He-4, in regards to both temperature and pressure. How can I go about calculating the standard volume at a more workable pressure or mass of the supercritical fluid? I'm having problems finding compressibility information at this high of a pressure.

 

Thanks,

Hank

[MrShorty]

Perhaps some clarification: What do you mean by standard volume? Off the top of my head, the main "reference" or "standard" volume for gases is usually ideal gas (where z=1).

 

Where have you looked for compressibility information at these pressures? My first reaction was to check my copy of NIST's REFPROP (9.1) which allows me to calculate compressibility for Helium up to 1000 MPa. Checking NIST's website (http://webbook.nist....hemistry/fluid/ ) based on REFPROP 7, it only allows the calculation up to ~100 MPa, suggesting to me that NIST believes they have enough data for helium between version 7 and version 9.1 to justify increasing the pressure limit. If you have access to REFPROP, that could be a resource to consider. It might be worth researching where they are getting their data.

[Bobby Strain]

I would ask whomever filled the cylinder. They probably know how much they put into it.

 

Bobby