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psv for a LH2

psv for a LH2

psv for a LH2

I’m working with liquidized hydrogen that is stored in a vessel at cryogenic temperatures.

I'm trying to size a relief valve for that vessel. One of conditions where the safety or relief valve is needed is when the tank temperature rise close to ambient temperature due an issue with insulation or coolant media.

I need to know the relation between temperature and pressure in the vessel. Do you recommend any bibliography that cover that issue?

RE: psv for a LH2

Size the relief valve per CGA S-1.3. If your relieving pressure is below critical pressure (about 175#) it will be the saturation temperature. If it is above the critical pressure, then the relieving temperature is a bit more complicated to calculate. You will also have to account for the pressure drop and temperature increase from the PSV inlet piping.

I recommend you do not take this task lightly, and realize that for a loss of vacuum insulation event, you may have condensation of air on the vessel which is a substantial heat flux and safety risk.

RE: psv for a LH2

In USA you are required to follow all of OSHA 1910.103, which specifies the relief sizing csk62 referenced.

Special heat input equations. No fire credit factors. Use entire vessel's surface area for fire case.

Good Luck,

RE: psv for a LH2

thanks a lot for the answers.

RE: psv for a LH2

XX05, I see you are new here. Welcome!

There is a button on bottom, right of each post to reward a great post/show thanks.

Good Luck,

RE: psv for a LH2

Your assumption that relief may occur when LH2 approaches ambient temp may not be true - it may relieve at much lower temp, and this depends on the mechanical design pressure of the LH2 vessel. Check the thermo tables for saturated H2 to see what this temp will be.

RE: psv for a LH2


You mention running fire calculations for the entire vessel surface area. If the only fuel for a fire is the tank contents itself shouldn't that require a review of the possibility of a sustained pool fire? You may be referring to another fuell source but I just wanted to clarify the basis for complete fire calcs for a hydrogen vessel. It may be possible to develop a pool fire for liquid hydrogen just I wonder how much of a tank leak is needed to feed a sustained pool fire with hydrogen.


RE: psv for a LH2

Read OSHA 1910.103.

It tells you what is required by law.

Good Luck,
Pats' Pub's Proprietor

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