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3710 and 3720 Positioners
accessories. Be sure the actuator
cannot suddenly open or close the
valve.
D Use bypass valves or completely
shut off the process to isolate the
valve from process pressure.
D Vent the actuator loading
pressure.
D Use lock-out procedures to be
sure that the above measures stay in
effect while you work on the
equipment.
D Check with your process or safety
engineer for any additional measures
that must be taken to protect against
process media.
Positioner Maintenance
Replacing the Standard or Beacon
Indicator
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
1. Remove the positioner cover assembly (key 7).
2. Remove the four machine screws (key 8) that
hold the indicator scale (key 14) to the positioner
cover. Remove any other external indicator parts
such as the pointer (key 13).
The standard, low-profile indicator
uses a retaining ring (e-clip) (key 12)
inside the positioner cover. The
retaining ring holds the indicator. After
28
Note
removing the external scale, remove
the internal retaining ring to free the
indicator.
The optional beacon indicator uses a
retaining ring (e-clip) (key 12) on the
outside of the positioner cover. The
retaining ring holds the extension
shaft. After removing the beacon
indicator, remove the external
retaining ring to free the extension
shaft.
3. Remove the internal or external retaining ring that
holds the indicator/extension shaft. Remove the
indicator/extension shaft from the positioner cover.
4. Install the new indicator/extension shaft and
secure it with the retaining ring. Install other indicator
parts and properly align the indicator using the
procedure given in this instruction manual.
Removing the Type 3722 Converter
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
See figure 24.
1. Be sure all safety procedures have been
followed. Remove the input wiring and supply
connection from the installed Type 3722 housing.
2. Remove the two mounting screws (key 84) and
carefully separate the converter from the positioner
base plate. Locate the two O-rings (key 85) and
inspect them. Save or replace as necessary.
3. Be sure the input and supply ports in the
positioner base plate are clean. Apply sealant (key
64) to the threads of any pipe nipples or other
connectors to be installed in the ports in the
positioner base plate. Connect pneumatic input and
supply pressure to the positioner, if necessary.
Instruction Manual
Form 5300
July 2005
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