Technical Guide
DAN-LIQ-TG-44-rev0813
November 2013
37
7-3 CLOSED POSITION - The solenoid pilot is de-energized. This blocks the supply of pressure
and vents the power cylinder pressure (P3) to atmosphere. The power cylinder spring provides the
differential force to close the main valve piston and keep it seated. The valve will not allow flow
from the forward or reverse direction. 7-4 OPEN POSITION - The solenoid pilot is energized, thus
opening the supply pressure to the power cylinder (P3). The supply pressure is equal to or greater
than the total spring force. This keeps the valve in a full-open position. Product can flow through
the main valve in either direction.
Figure 7-4
OPEN POSITION - The differential pressure between (P1) and (P2) has exceeded the total spring
force of the power cylinder spring (P1 minus P2). This keeps the valve in a full-open position.
Figure 7-3
= Pump and Valve
Outlet Pressure
= Valve Inlet Pressure
Figure 7-2
= Inlet Pressure
= Outlet Pressure
= Power Cylinder Supply Pressure
= Power Cylinder Spring Force
P2
P1
3-Way Solenoid
Pilot (N.C.)
Opening
Speed
Closing
Speed
Supply
Pressure
Exhaust
Power
Cylinder
Vent
P2P1
P3
P2P1
P3
(Open)
(Closed)
Flow
Power
Cylinder
Sense
Line (HI)
Sense
Line (LO)
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