Discharge of PSV/PRV

**Ash1785** · 02-05-2010, 08:51 AM

Is it necessary to vent a balance bellows type PSV/ PRV always to the atmosphere ?

Can't the discharge be sent to a tank or line instead ?

**rathore_mbm2002** · 02-07-2010, 04:40 PM

Originally Posted by Ash1785

Is it necessary to vent a balance bellows type PSV/ PRV always to the atmosphere ?

Can't the discharge be sent to a tank or line instead ?

Vent pipe of PSV/PRV if diverted to tank then very purpose of valve will be defeated in view of back pressure on PSV. But vent can be sent to pipe which in turn connected to flare line open to atmosphere.

**armin35** · 02-07-2010, 05:27 PM

if is Steam you can vented to ATM but anything else but steam should be diverted to Flare and is always good idea to be a Balanced Bellows type valve.

**rathore_mbm2002** · 02-07-2010, 05:52 PM

Originally Posted by armin35

if is Steam you can vented to ATM but anything else but steam should be diverted to Flare and is always good idea to be a Balanced Bellows type valve.

As I have seen all critical plant safety valves are open to atmosphere as for steam and for Other pcocess fluid/toxic gases which needs to burn are connected to hot flare of plant.
For positive displacment pumps(like screw pumps) there is always pressure safety valve which diverts flow from discharge side to suction side if limit crosses.