Emerson Daniel 700 Series

Technical Guide
DAN-LIQ-TG-44-rev0813
November 2013
33
OPEN CONTROLLED POSITION - The solenoid pilot is closed (de-energized). The back pressure
pilot is partially open, bypassing the solenoid pilot. Inlet pressure has slightly exceeded the back
pressure pilot spring setting. Z-port (P2) is being opened by the throttling of the pilot, reducing the
pressure on Y-port (P3). The decreasing pressure at Y-port (P3) plus the main valve spring force
establishes a position of the valve piston such that it balances inlet pressure (P1) equal to the pilot
setting (Plus or minus 2 psi).
FULL OPEN - NO CONTROL - The solenoid pilot is open (energized), bypassing the back pressure
pilot which is closed. As long as the solenoid pilot is open, the back pressure control function is
bypassed and cannot perform, even though inlet pressure (P1) 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.
X
Z
Y
X
Z
Y
X
Z
Y
Figure 5-5
P3
P2
P1
X
Z
Y
X
Z
Y
X
Z
Y
Figure 5-6
P3
P2P1
= Inlet Pressure
= Outlet Pressure
= Pilot Spring Force
= Inlet Pressure
= Outlet Pressure
= Controlled Pressure
= Pilot Spring Force
Solenoid Pilot (N.C.)
Pressure Reducing Pilot (N.C.)
Sense Line
Needle Valve/Strainer
(Closing/Sensitivity Control)
Solenoid Pilot (N.C.)
Pressure Reducing Pilot (N.C.)
Sense Line
Needle Valve/Strainer
(Closing/Sensitivity Control)