Emerson Daniel 700 Series Technical Manual page 37

Technical Guide
DAN-LIQ-TG-44-rev0813
November 2013
OPEN - CONTROL POSITION - The normally closed solenoid is closed. The normally open solenoid is closed.
Y-Port (P3) to Z-port (P2) is closed. X-port (P1) to Y-port (P3) is closed. The product cannot flow to or from
the top of the piston. The piston is hydraulically locked in position until the electronic preset commands the
Limit
Switch
Position
Y
Indicator
Y
Z
X
= Inlet Pressure
= Outlet Pressure
= Controlled Pressure
X
OPEN POSITION - (no control) - The normally closed solenoid is open. The normally open solenoid is closed.
Y-port (P3) is open to Z-port (P2). X-port (P1) is closed off by the normally open solenoid. The pressure on the
bottom of the piston (P1) is greater than the pressure at (P3) plus the spring force; (P1 minus P2) is equal to
or greater than the spring force. Therefore, (P1) pressure pushes the piston open. No flow control is required.
= Inlet Pressure
= Outlet Pressure
Solenoid Pilot (N.O.)
Strainer
P1
Limit
Switch
Position
Y
Indicator
Y
Z
Solenoid Pilot (N.O.)
Y
X
Strainer
P1
Solenoid Pilot (N.C.)
P3
Y
Z
X
Figure 6-2
X
Solenoid Pilot (N.C.)
Z
P3
Y
Z
X
Figure 6-3
35
Needle
Valve
P2
Y
Z
Needle
Valve
P2