Altering the test medium of PSV 1

[Gadam B]

Hello everyone,
I have a question regarding PSV testing medium altering. I have PSV testing bench with capacities 900 barg for water medium and 250 barg for air medium. What if I test the PSV installed at nitrogen line with water at 420 bag, instead air. This is due to limitation of my test bench. For short term mitigation can I test my PSV at 420 barha with water, instead of air. Much appreciate your feedback on this clarification. Looking forward your soonest possible response.
Kind regards,
Gadam B

 

[The Obturator]

Its not recommended you do this. API-527 clearly states that Pressure-relief Valves on non compressible fluid service be tested on water, and compressible fluids on air (or nitrogen). For a start, you would get different results between the two tests. Also, many modern PRV's for liquid service have different trims and ring settings to those on compressible fluids and react differently when opening. If the valve is coded, then this is further not permitted. why do you want to take short cuts for a safety valve there for the protection of life and property?


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[gguliye]

Hello,
In the manufacturer that i am working, we have different trim styles for the water and gas. Point is that our liquid trim is certified for the gas also, but spring becomes different at different CDTPs. In other words, the valve on gas service is not the same valve on liquid service and the spring range becomes different together with trim styles
Not recommended!

 

[Gadam B]

Hello guys,

First of all, thank you very much for your quick feedbacks.
Actually I also don't want to do so. Due to pressure output limitation of my test bench (max.250 bar for nitrogen compartment) I am looking for the opportunity that allows by Codes/Standards to alternate the testing medium from gas to water. While my PSV requires set pressure @ 420 bar, my test bench can supply pressure with water upto 1000 bar and with nitrogen only 250 bar. Therefore, I decided to ask in the forum if somebody practiced successfully such kind of medium altering.
I guess, I need to expedite purchasing the pressure booster to compensate nitrogen compartment of my testing bench.
Thank you!

Kind Regards,
Gadam B.

 

[Gadam B]

Hello guys,

First of all, thank you very much for your quick feedbacks.
Actually I also don't want to do so. Due to pressure output limitation of my test bench (max.250 bar for nitrogen compartment) I am looking for the opportunity that allows by Codes/Standards to alternate the testing medium from gas to water. While my PSV requires set pressure @ 420 bar, my test bench can supply pressure with water upto 1000 bar and with nitrogen only 250 bar. Therefore, I decided to ask in the forum if somebody practiced successfully such kind of medium altering.
I guess, I need to expedite purchasing the pressure booster to compensate nitrogen compartment of my testing bench.
Thank you!

Kind Regards,
Gadam B.