CVS 1051 Series, Instruction Manual

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Principle of Operation
As the loading pressure is increased on top of the
diaphragm the diaphragm rod moves down. As the
loading pressure is decreased, the diaphragm rod is
forced upward by the spring.
The spring and diaphragm have been selected to
fulfill the requirements of the application. When in
service the actuator should produce full travel of the
valve with the diaphragm pressure as indicated on
the nameplate (Figure 2)
For principle of operation of the actuator with a valve
positioner, refer to the separate positioner manual.
Maintenance
Actuator parts are subject to wear and tear which
requires inspection and replacement as necessary
according to the severity of service conditions. The
following instructions outline adjustment,
disassembly and reassembly of parts. Refer to
Figures 7 & 8 for Key Numbers.
Warning: The sudden release of process
fluid can cause personal injury or property
damage. Prior to starting adjustment
procedures:
• Isolate the valve from the process,
•
Release the process pressure, and
• Vent the actuator loading pressure.
Disassembly
The CVS Type 1051 Actuator can be completely
disassembled by following these procedures. When
inspecting or repairing the actuator, perform only
those steps necessary. Under normal conditions,
the cap screws (Keys 2, 42 and 43) should not be
removed.
Note: Cap screw (Key 12) must be
disengaged from the lever (Key 33) prior to
removing the diaphragm casing (Key 26).
Failure to do so will allow the spring
compression to rotate the valve beyond its
fully open or closed position. This could
cause damage to the valve seal.
1. Bypass the control valve, relieve all loading
pressure and remove the tubing or piping from
the top of the actuator.
2. If the control valve assembly includes a valve
positioner, remove it from the assembly.
3. Remove the cap screws and washers (Keys 8
and 9) as well as the cover (Key 41).
4. Remove the retaining ring and then the hub
(Keys 36 and 30) from the cover.
5. Inspect the bushing (Key 40). If replacement is
necessary, remove the travel indicator scale
(Key 39) by first unscrewing the self-tapping
screws (Key 37).
6. Remove the cap screw and hex nut (Keys 12
and 31).
7. Note the orientation of the lever/valve shaft, and
then loosen the cap screw (Key 10).
Note: Avoid using a hammer to drive the
lever (Key 33) off of the valve shaft. On some
valve types this could cause the valve ball
and bearings to move from their centered
position, causing damage to valve parts
during operation.
If using a tool is necessary, use a wheel
puller to remove the lever. Tapping the wheel
puller screw lightly to loosen the lever is
permissible, but hitting the screw with
excessive force could also cause damage to
valve parts or disrupt the positioning of the
valve ball and bearings.
Warning: Before proceeding further, remove
the cap screws and relieve the spring
compression. Failure to do so may cause
personal injury if the compressed spring
force suddenly thrusts the upper diaphragm
casing away from the actuator.
8. Loosen but do not remove the casing cap screws
(Key 45). Ensure that all spring force in the
upper diaphragm casing has been relieved.
Unscrew and remove the cap screws and hex
nuts (Keys 45 and 44) then remove the upper
diaphragm casing and the diaphragm (Key 25).
9. Refer to the warning on the CVS Controls
nameplate (Key 27) located on the diaphragm
plate (Key 1).
10. Remove the diaphragm plate (Key 1) and the
attached parts from the actuator. The following
parts will be attached to the diaphragm head:
spring (Key 21), diaphragm rod (Key 22), cap
screw (Key 24), spring seat (Key 19), hex nut
(Key18), turnbuckle (Key 16), hex nut (Key 14)
and rod end bearing (Key 13).
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