In PCV & SDV, in that there are two terms
a. Shut off pressure
b. Maximum differential pressure for Actuator sizing
The system sequence is
Vessel A ( Oper.Pres.= 4.5 barg)
-----> PCV( Press. Drop=4 bar)
-----> Vessel B (oper. Pres.=0.5 barg)
Vessel A design pressure = 12.0 barg
Vessel B design pressure = 4.0 barg
- PCV - Pressure control valve
** SDV - Shutdown Valve
Please suggest the values for the both terms for the PCV & SDV to fill.
a. Specify shut off pressure for valve tightness purpose… Worst case is design pressure-ATM = 12 bar.
b. Specify maximum differential pressure for actuator design. Large Differential Pressure across control valve, large torque required and larger the actuator (& cost). Actuator also increase with line size. In order to reduce cost, normally you put a small bypass for pressurization purpose…