API 520 PRV Reaction Force Calculation
API 520 PRV Reaction Force Calculation
(OP)
For the API 520 All Vapor Flow case reaction force calculation (API 520, PArt II, 4.4.1.1), a component P is referenced as the static pressure in discharge pipe at point of discharge. What value is this? Is this 0 psig for all discharges to atmosphere? Is it the built up back pressure due to the discharge at the time of discharge minus the pressure drop due to friction along the discharge pipe?





RE: API 520 PRV Reaction Force Calculation
This is the static pressure at the point of discharge, so for instance if the PSV is discharging to atmosphere this value will be 0, if on the other hand it is discharging to a vessel operating at 14 psig, this value will then be 14 psig.
Or at least it is what I would have done.
Regards.
RE: API 520 PRV Reaction Force Calculation
RE: API 520 PRV Reaction Force Calculation
Can you give me an example of a situation that you are talking about? Maybe a sample calculation on where the static pressure is not 0 PSIG for an atmospheric discharge.
Thanks.
RE: API 520 PRV Reaction Force Calculation
API 521 (or 520?) shows how to calculate the critical pressure (Pc) at which the fluid reaches Mach 1. That is the pressure that I would use.