velocity criteria for PSV suction line

[KVVS]

Dear All,

there is any guideline regarding velocity criteria for PSV suction .
thanks in advance

 

[Latexman]

You mean the inlet line to the PSV, right?

Good luck,
Latexman

 

[KVVS]

right sir, there is any guideline regarding velocity criteria for inlet PSV line. Some where i read that 70% of sonic velocity can treat as for same. can i take this for all time ?
please help me.

thanks in advance

 

[joerd]

No, there is just the "3%" rule, see API 520. 70% of sonic is way too high.

Cheers,
Joerd

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Petroprocess]

I would agree with joerd. There is just the "3%" rule for the grass root design as per API guideline. Although I have seen engineers take slightly higher pressure drop acceptabe in older/existing facilities.
So when you design for 3% od set pressure of PSV as pressure drop (inlet line)the velocity you get is the acceptable velocity.