Different Between Shut Off Pressure & Differential Pressure for Actuator Sizing

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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)
-----> SDV
-----> 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...
by JoeWong

Reference :
i) Requirements of SDV Bypass Pressurization Line