Technical Guide
DAN-LIQ-TG-44-rev0813
November 2013
X
Z
Y
Needle Valve/Strainer
(Closing/Sensitivity Contol)
Pressure Reducing Pilot (N.O.)
Sensing Chamber Line
18
Model 750 Pressure Reducing Control Valve (N.O.)
Closes on increasing Outlet Pressure
A pressure reducing valve is normally open and throttles toward a closed position on increasing outlet pressure. It is a regulating
or positioning type valve that does not require any outside power source to operate.
The pilot control is normally open. It is an adjustable spring loaded variable orifice in the Z-port. The pilot is piston operated,
spring biased (loaded) with a pressure sensing chamber connected on the downstream (P2) side.
Pressure reducing valves are used for:
1. Precise pressure control in process streams.
2. Over-pressure protection of meters, pipe line manifold systems, etc.
= Inlet Pressure
= Outlet Pressure
= Pilot Spring Pressure
FULLY OPEN - NO CONTROL - The pilot is fully open. Open pressure (P2) is less than the pilot
spring setting. Y-port (P3) is open to Z-port (P2). The valve is floating the stream and is not
required to control.
P1
P3
P2
Figure 4-6
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