Instruction Manual
D102602X012
657NS Actuator
November 2012
6
CAUTION
Incomplete engagement of the valve stem and/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 the
diameter of that 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, if present, before clamping the stems together.
9. Reduce loading pressure until the temporary mark on the actuator stem is parallel with the top mark on the
indicator scale.
10. Pull the valve stem firmly against its seat, and be sure that it remains firmly against the seat. Clamp the actuator
stem and valve stem between the two stem connector halves. If necessary, increase loading pressure slightly to
allow the valve stem, actuator stem, and stem connector threads to match.
Insert and tighten the stem connector cap screws.
11. Raise the travel indicator disk to the stem connector (sizes 40 through 70 only). For all sizes, thread the stem
locknuts against the stem connector.
12. Remove all loading pressure. Move the travel indicator scale so that the indicator disk (or pointer) is in line with the
top mark of the travel indicator scale.
13. Check the valve travel to be sure that the valve travels fully with no overtravel.
Loading Connection
1. Connect the loading pressure piping to the NPT internal connection in the top of the actuator yoke.
2. For size 70 actuators, remove the 1/4-inch bushing in the 1/2 NPT internal connection 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 a volume
booster, valve positioner or other accessory is used, be sure that it 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.
