Fisher 657 - Manual (Page 4)

Instruction Manual
D100307X012
657 Size 80 and 100 Actuators
December 2010
4
2. Screw valve stem locknuts (key 16, figure 4) all the way onto valve stem thread.
3. Connect an air supply to the diaphragm casing.
4. For push‐down‐to‐close valves, be sure the valve plug is on its seat. Apply pressure to ensure that the actuator stem
is fully extended. Reduce actuator loading pressure to retract the stem approximately 3.2 mm (1/8‐inch).
5. For push‐down‐to‐open valves, move valve plug to closed position. On large body sizes, this may require the use of
a pry bar inserted through the body line opening. If the body is installed in a pipeline, the bottom flange (if one is
used) can be removed and the valve plug pushed to the seat from the bottom opening. Pressure the actuator to
move the stem out 3.2 mm (1/8‐inch).
WARNING
To avoid personal injury due to the sudden uncontrolled movement of parts, do not loosen the stem connector cap screws
when the stem connector has spring or loading pressure force applied to it.
CAUTION
Incomplete engagement of both valve stem and actuator stem in the stem connector can result in stripped threads or
improper operation. Be sure that the length of each stem clamped in the stem connector is equal to or greater than the
diameter of that stem.
6. Clamp the actuator and valve plug stems between the two stem connector halves (key 26, figure 4). Insert and
tighten the stem connector cap screws.
7. Thread the stem locknuts against the stem connector.
8. Align the travel indicator scale (key 18, figures 4 and 5) to show valve position.
Loading Connection
1. Connect the loading pressure piping to the connection in the top of the diaphragm casing.
2. Remove the 1/4‐inch bushing (key 33, figure 4 and key 120, figure 5) to increase connection size, if necessary. The
connection can be made with either piping or tubing.
3. Keep the length of tubing or piping as short as possible to avoid transmission lag in the control signal. If an
accessory (such as a volume booster or valve positioner) is used, be sure that the accessory is properly connected to
the actuator. Refer to the positioner instruction manual as necessary.
4. Cycle the actuator several times to check that the valve stem travel is correct and that the travel occurs when the
correct pressure range is applied to the diaphragm.
5. If valve stem travel is incorrect, refer to the Travel procedure in the Adjustments section.
6. If the pressure range is incorrect, refer to the Spring procedure in the Adjustments section.
Adjustments
Travel
Make travel adjustments when the motion observed during actuator travel is different from the travel stamped on the
actuator nameplate. If the Actuator Mounting procedure was followed correctly, this adjustment should not be
necessary.