Flowserve PMV D3 Digital Positioner - Manual (Page 11)

11
Single action positioner
(Direct function)
Actuator with closing spring
When the control signal increases, the
pressure C+ to the actuator is increased. The
valve spindle moves upward and rotates the
positioner spindle counter-clockwise. When
the control signal drops to zero, C+ is vented
and the valve closes.
Actuator with opening spring
When the control signal increases, the
pressure C+ to the actuator is reduced. The
springs press the valve spindle upward and
the positioner spindle rotates counter-
clockwise. When the control signal drops to
zero, C+ is vented and the valve opens.
Double action positioner
(Direct function)
Double action actuator
When the control signal increases, the
pressure C+ to the actuator is increased. The
valve spindle is pressed upward and rotates
the positioner spindle counter-clockwise.
When the control signal is reduced, the
pressure C- to the actuator increases and the
valve spindle is pressed downward. If the
control signal disappears, the pressure goes
to C-, C+ vents, and the valve closes.
C–
S
C+
C–
S
C+
C–
S
C+