Jim - your email isn't really clear....What do you want to check about the operating PSV???? Some things you might want to check(!):
1) Does it exist!!!!????
2) Is it installed correctly
3) Is it the right size
Those are some examples of WHAT to check........WHAT do you want to know....?
I want to check it size and installed correctly, such as if the inlet prossure drop if less than 3%,back pressure is not more than 110% for conventional PSV, etc. If not good, I have to size it again.