Sizing PSV with dual discharge lines

[rinats]

Hi all,
Doing PSV evaluation originally done by another company I found that instead of 8X10 PSV (we are using some in house software plus I run software by another PSV Vendor to confirm results) (psv to be installed on compressor discharge line with compressor capacity around 520 MMSCFD, methane service, block flow case) they recommended to install 6X8X8 PSV. They recommended to use Anderson Greenwood Pilot Operated PSV model 200. What are the advantages going with smaller psv other than reducing cost associated with smaller line (pipe, connections, etc. )? How do we size this type of PSV (dual discharge)? Do we use a modified formula for Gas/Vapour critical flow ? If this is the case can you provide some info on sizing technique for this type of applications?


Thanks in advance,

 

[BenThayer]

not sure why you sized for a 8x10 vs. 6x8 but one of the most common "mistakes" for a compressor is to assume that the "all" the flow needs to exit.

you really just need the minimum flow to get to a safe state on the compressor's operational curve. this typically results in a significantly smaller PSV.

is there a link to a cut sheet for the A-G PSV you could reference?