Hydrogen relief valve calculation

[snj_2000]

Hello,
I am having problems with a Pressure relief valve calculation due to a non ideal gas (hydrogen)

There is a high pressure vessel (410bar) hydrogen with 3mm ID process pipework leading to a 450bar PRV with 7mm ID orifice to atmosphere

My question is 2 part:

1) For the maximum flow rate of hydrogen out of the PRV @ 450bar should I use 3mm (process pipework) or 7mm (PRV orifice) ID as the tube size for the calulation? Logic says 3mm ID as this is the choking pipework before the PRV so will determin the max flow rate.

2) What woud be the calculated maximum flow rate for the hydrogen gas if the PRV lifted at 450bar and vented to atmosphere?

Thanks for your help in advance!

[admin]

I think discharge calculator will be the perfect tool for your problem:
http://www.pipeflowcalculations.com/gasleak/
Also you can find theory used in calculator at:
http://www.pipeflowcalculations.com/pip ... -and-pipes

I think that 3mm pipe max flow will give you lower flow rate than 7mm PRV but you can check it with calculator anyway.

Your feedback is welcome.