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2.
See WARNING in this section. Sequentially loosen
fasteners securing base to frame. Base pops up from
frame when fasteners disengage.
3.
When tension is relieved, remove fasteners and base.
4.
Install new base assembly.
5.
Reinstall fasteners.
Reassemble Actuator assembly by following
6.
procedure in Steps 1 and 2 in reverse order.
Reinstall air lines and restore system to service.
7.
REPLACE ACTUATOR MAIN
SPRING
Remove the main spring
by following the procedure in REMOVE ACTUATOR
COVER under MP953A, C, E DIRECT-ACTING
ACTUATORS in REPLACE MAIN DIAPHRAGM
section. This procedure relieves all internal spring force and
makes the spring fully accessible.
See PARTS for the proper replacement spring.
Remove the main spring on reverse-acting Actuators
safely by following the procedure in MP953B, D, F
DIRECT-ACTING ACTUATORS in REPLACE MAIN
DIAPHRAGM section. This procedure relieves all internal
spring force and makes the spring fully accessible.
See PARTS for the proper replacement spring.
REPLACE GRADUTROL RELAY/
POSITIVE POSITIONER
When using the following procedure, see Figure 8 for an
exploded diagram and Table 6 for parts.
To prevent damage to the MP953E, wrench force must only
1.
Disconnect all air lines.
2.
Unscrew Relay/positioner counterclockwise from
Actuator cover and remove.
on direct-acting Actuators
NOTE: Considerable force may be required before
3. Remove feedback spring. Retain old spring for
4. Install original feedback spring in diaphragm cup
when Relay/positioner is being replaced with an
identical device.
5. When replacing Gradutrol Relay with a new-style
positive positioner, discard original spring and install
feedback spring with proper range from appropriate
retrofit kit. For part number, see POSITIONER
RETROFIT AND SPRING KITS in PARTS AND
ACCESSORIES.
6. Position new O-ring in groove of Relay/positioner
base and install new Relay/positioner in Actuator
safely
cover.
NOTE: Compress feedback spring as the Relay/
7. Tighten Relay/positioner only enough to seat large O-
of position and damage Actuator diaphragm and
feedback spring when unit is destroked.
8. Reinstall air lines and restore system to service.
9. Adjust range (MP953A only) and/or start point. See
MAINTENANCE.
When using the following procedure, see Figure 9 for an
exploded diagram and Table 7 for parts
Disconnect all air lines, including short tube from
Relay/positioner to side of Actuator cover.
Remove three screws that locate the Relay/positioner
bracket assembly on the Actuator cover.
Remove bracket assembly. Retain original bias and
feedback springs when Relay/positioner is being
replaced with an identical device,
When replacing Gradutrol Relay assembly with new-
style positive positioner assembly, discard original
bias and feedback springs and install springs with
proper range from appropriate retrofit kit. For part
number, see POSITIONER RETROFIT AND
SPRING KITS in PARTS AND ACCESSORIES.
the positioner begins to turn because of the
large O-ring that seals the Relay/positioner
to the Actuator cover.
positioner is screwed in place. Check that
both ends of the feedback spring are located
in the spring cups, one in the Relay/
positioner and one cemented to the Actuator
diaphragm.
75-5500
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