Hi guys ;
I determined the discharge orifice area with hysys v8.8 ( the calculated area is equal to the result in API 520 example).
Trying to use pressure relief utility in Hysys v8.8 to Line size the inlet and the outlet tail pipes, i found that hysys uses these constraints :
Inlet pressure drop <3% Set pressure
outlet pipe avg velocity < 50 % of sonic velocity
outlet pipe exit < 90% of sonic velocity
Since i'm new, i want to know if this is correct , because i read on this forum and internet that generally we use these constraints :
Inlet pressure drop <3% Set pressure
pressure drop < 10 % of set pressure (if conventional)
pressure drop < 50 % of set pressure (if balanced)
pressure drop < 100 % of set pressure (if pilot)