Instruction Manual
D103799X012
685SE/685SR Piston Actuator
September 2014
8
connector slightly, tightening the locknuts together, and (with the valve plug off the seat) screwing the stem
connector either into or out of the stem connector by means of a wrench on the locknuts.
7. If the total travel is adequate, tighten the stem connector (key 18) securely, lock the stem locknuts (if present)
against the connector, and adjust the indicator scale (key 22) on the yoke (key 21) to show valve plug position.
8. Provide a gauge, if necessary, to measure the pressure to the actuator. Make a final adjustment on the positioner to
set the starting point of valve travel and to obtain full travel for the given instrument range.
Handwheel Operation
If manual operation is required, the actuator should be equipped with a manual handwheel for sizes 10 to 26.
CAUTION
To avoid damage to actuator parts and difficult operation of actuator handwheels, open the bypass valve (key 66) before
using a handwheel.
The bypass assembly is furnished only when a handwheel actuator is specified. The bypass allows the pressure to
equalize on either side of the piston, so that the manual actuator can be used to position the control valve. Flow
through the bypass tubing is controlled by an angle needle valve, which is operated manually. This valve should be
closed when air pressure is being used to operate the actuator.
Key numbers referenced in the following steps are shown in figure 4 and 5 . Refer to table 7 for handwheel
specifications.
1. Open the bypass valve.
2. Rotatethehandwheel(key45)topositiontheoverrideengagepin(key38)withtheholeinthestemconnector
(key 10). Turn the engage pin control knob (key 33) clockwise to insert the override engage pin into the stem
connector until it stops.
Note
Depending on construction , the h andwheel may have operation information stamped into the part. Always refer to steps 3 and 4
for operation information specific to pushdowntoclose and pushdowntoopen valves.
3. For a push-down-to-close valve: Rotate the handwheel (key 45) clockwise to close the valve and counterclockwise
to open the valve.
4. For a push-down-to-open valve: Rotate the handwheel (key 45) counterclockwise to close the valve and clockwise
to open the valve.
5. To disengage t he manual handwheel, rotate the handwheel (key 45) to relieve any load placed on the override
engage pin (key 38), turn the engage pin control knob (key 33) counterclockwise until it stops.
(28 paginas)
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