21
SEMPELL
MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
FUNCTION SIERION
In normal operation, pre-pilot disc 1 is closed
and disc 2 opened. Disc 3 is also closed
and system pressure predominates in the
chambers A, B and C. The system pressure in
the lower bellows attempts to push the flange
upwards, but this is prevented by the attached
disc spring package.
As system pressure rises in the bellows
chamber, the plunger is moved below disc 1
and attempts to detach it from its seat in disc 2.
Because of the Δp existing here, however, this
cannot be accomplished at first and disc 2 is
also lifted, up to its seat. Disc 2 is closed. Disc 1
is still closed and seals to the atmosphere.
Disc 1
Closed
Disc 2
Open
Disc 3
Closed
Chamber A
System pressure
Chamber B
System pressure
Chamber C
System pressure
Disc 1
Closed
Disc 2
Closed
Disc 3
Closed
Chamber A
System pressure
Chamber B
System pressure
Chamber C
System pressure
Summary of Contents for Sempell PSRV VS99
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