
Consolidated 2900-40 Series POSRV Maintenance Manual | 19
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X. Operating Principles
Figure 4: Pilot Valve (Closed)
A. PV Valve Closed (Normal Position)
System pressure from the main valve inlet is fed to the dome by the pilot through interconnecting tubing. This
equalizes the pressure on the top of the piston with inlet pressure on the seating surface (bottom) of the disc.
Since the area of the top of the piston is larger than the area of the seating surface, the differential area results in a
net downward force keeping the main valve tightly closed.