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SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
FUNCTION DPDE
Motors Close signal
Disc 1 Closed
Disc 2 Closed
Chamber A System pressure
Motors Open signal
Disc 1 Open
Disc 2 Open
Chamber A Reducing pressure
The DPDE consists of a body with two valve
inserts for reliable closing function. Both valves
function differently. Disc 1 closes the valve
through the system pressure and the pressure
spring below the disc, while disc 2 closes the
valve against system pressure by means of a
motor. In normal operation, both valve discs 1
and 2 are closed and therefore, so is the pilot
line A to the main valve.
If the motors receive the signal to open from
the pilot chamber, disc 1in the first valve is
pushed open by the plunger. In the second
valve, disc 2 is raised. The pressure in pilot line
A to the main valve is reduced.
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