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Instruction Manual
D103472X012
5. If movement occurs before or after the upper bench set pressure is reached, adjust the spring adjusting screw (key
127) turn it clockwise to increase the preload in the spring (key 110) or turn it counterclockwise to decrease the
preload in the spring until the actuator stem (key 125) movement is first detected at the upper bench set pressure.
6. Slowly decrease the pressure on the bottom of the diaphragm (key 105) until the lower bench set pressure is
reached.
7. Mark a line on the actuator stem (key 125) and another on the leg of the actuator yoke or yoke/diaphragm casing
assembly (key 109), making sure the lines are level.
8. Slowly increase the pressure on the bottom of the diaphragm (key 105) until the upper bench set pressure is
reached.
9. Measure the distance between the two lines. This distance should be equal to the rated valve travel.
10. If the distance is correct, bench set is complete. Proceed to the Installing the Stem Connector Assembly
subsection.
11. If this distance differs from the rated valve travel, verify that the correct spring and actuator stem are being used
and verify that the upper bench set pressure is correct. Remember the freelength and load rate tolerances for the
spring may produce a slightly different span than specified. Contact your
replacing the spring, repeat the steps above.
12. Bleed the pressure from the bottom of the diaphragm (key 105), and remove the air hose from the port in the top
of the yoke (key 109) for size 45 and 70, or the bottom of the lower diaphragm casing for size 80.
Installing the Stem Connector Assembly
When installing the stem connector assembly (key 103), the actuator and valve stem threads should engage the
threads of the stem connector by a distance equal to the diameter of the stem.
1. If necessary, push the valve stem down so that the valve plug is touching the seat ring on directacting valves.
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 it, if present, before clamping the actuator and valve stems together.
2. If necessary, screw the valve stem locknuts down, away from the connector location.
3. Adjust the diaphragm pressure to the lower bench set pressure. This should be the same pressure used in the bench
set steps, and it is marked on the nameplate.
4. Place the stem connector half (key 103B) with the threaded holes, approximately halfway between the actuator and
valve stems. Refer to figures 4 to 9 to help locate the connector position.
WARNING
Incomplete engagement of either the valve stem or actuator stem in the stem connector can result in stripped threads, loss
of process control, and/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.
5. Attach the other stem connector half (key 103A) with the antirotator in the groove on the yoke or yoke/diaphragm
casing assembly and insert the hex cap screws (key 103C) and tighten them. If the actuator is to be used with a
positioner, the positioner feedback bracket will be held in place on the stem connector bolt half (key 103A) by the
667NS2 Actuator
Emerson sales office
for assistance. After
March 2022
11
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