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Installation, Operation and Maintenance Manual
MAN 564 Rev. 6
June 2020
Operation and Use
Section 3: Operation and Use
Figure 20
Modulating service
When modulating control is required as a function of a pneumatic or electric control signal,
a positioned (5) is used, which controls the supply to the actuator cylinder to keep the valve
in the required angular position. The positioner has a mechanical linkage to the actuator,
for a feedback of the valve position.
Pneumatic
positioner
Pneumatic
control signal
Electric control signal
Electropneumatic
positioner
Pressurized air (supply)
Reduced pressure air (opening chamber)
Reduced pressure air (closing chamber)
2
P
3
4
5
1
P
