Minimum PSV Set Pressure for API 520 Equations
Minimum PSV Set Pressure for API 520 Equations
(OP)
I'm calculating the capacity of an existing PSV with a set pressure of 0.8 barg. It is a conventional spring operated pressure relief valve. I'm using the PSV sizing equations from API 520 Part 1.
My concern is the validity of the API equations at the low set pressure of 0.8 barg. Is there a minimum set pressure at which the API 520 sizing equations can be applied?
Thanks.
My concern is the validity of the API equations at the low set pressure of 0.8 barg. Is there a minimum set pressure at which the API 520 sizing equations can be applied?
Thanks.





RE: Minimum PSV Set Pressure for API 520 Equations
select the correct set according your application,
the problem there could be the valve (make sure it works as expected)
RE: Minimum PSV Set Pressure for API 520 Equations
Low set pressure applications create problems for PSVs. It's often impossible to size a PSV that has the necessary capacity while satisfying the inlet pressure drop limit.
I'm assuming you're protecting a pressure vessel and not a tank. If you can raise the set P to 1 barg or higher (the higher the better) you'll have more options. You could then use a remote sensing pilot operated PSV to eliminate the inlet loss problem. Check with a couple of suppliers to explore specific options.
RE: Minimum PSV Set Pressure for API 520 Equations
RE: Minimum PSV Set Pressure for API 520 Equations
the problem for that application would not be the design but the selection of a suitable valve
RE: Minimum PSV Set Pressure for API 520 Equations