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Introduction
Open controlled position
Figure 1-2
illustrates the valve partially open. Differential pressure (P1 minus P4) has
slightly exceeded the pilot spring setting. Z-port (P2) is being opened by the throttling of
the pilot, reducing the pressure on the Y-port (P3). The decreasing pressure at Y-port (P3)
plus the main valve spring force positions the valve piston so that it balances the pump
differential pressure (P1 minus P4) equal to the pilot setting (Plus or minus 2 psid).
Figure 1-2:
Open controlled position
Fully open - no control
In
Figure 1-3
the valve is fully open. Differential pressure (P1 minus P4) has exceeded 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.
User Manual
5
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