Emerson Process Management FISHER 657 - Manual (Page 8)

Instruction Manual
D100306X012
657 Actuator (30-70 and 87)
December 2010
8
5. Slowly decrease the diaphragm loading pressure until the lower bench set pressure is applied. Measure the distance
between the marker or tape on the valve stem to the end of the actuator stem. The distance should match the
travel span shown on the travel indicator scale (key 18). If the span of travel is correct, bench set is complete.
Proceed to the Installing the Stem Connector Assembly subsection.
6. If the travel span is not correct, a wrong or damaged spring has been installed in the actuator. To obtain the correct
spring sizing information, refer to Catalog 14, Actuator Sizing and Sample Calculation sections to determine the
correct spring selection for your application. Or, contact your Emerson Process Management sales office for
assistance. After replacing the spring, repeat the steps above.
Installing the Stem Connector Assembly
When installing the stem connector assembly (key 26), the actuator and valve stem threads should engage the
threads of the stem connector by the distance of the diameter of the stem.
Note
Replacement stem connectors are an assembly of two stem connector halves, cap screws, and a spacer between the connector
halves. Remove the spacer and discard, if present, before clamping the actuator and valve stems together.
1. If necessary, push the valve stem down so that it is touching the seat ring on direct acting valves. For reverse acting
valves, push the stem down to the open position.
If necessary, screw the valve stem locknuts down, away from the connector location. For all actuators except size 87,
ensure that the travel indicator disk (key 14) is located on top of the locknuts.
2. Slowly increase the diaphragm pressure to the upper bench set pressure. This should be the same pressure used in
the bench set steps, and it is marked on the nameplate.
3. Place the stem connector half with the threaded holes, approximately half way between the actuator and valve
stems. Refer to figures 6, 7, and 8 to help locate the connector position.
Be sure that the actuator and valve stem threads are engaging the threads of the stem connector by the distance of
one diameter of the stem.
CAUTION
Incomplete engagement of either the valve stem or 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 one
diameter of that stem. Damage to threads on either stem or in the stem connector can cause the parts to be replaced
prematurely.
4. Install the other half of the stem connector and insert the cap screws and tighten them. If installing a positioner,
also attach the feedback bracket at the same time.
5. Screw the valve stem locknuts up until the indicator disk contacts the bottom of the stem connector, or for size 87
actuators, the stem connector. Do not overtighten the locknuts.
6. Slowly decrease and then increase pressure several times stroking the valve from the lower bench set pressure to
the upper pressure.
Be sure that the valve is in closed position (up or down, depending on valve action). Loosen the screws on the travel
scale, and align it with the travel indicator disk or stem connector. Stroke the valve full travel to ensure that the travel