Instruction Manual
D102602X012
657NS Actuator
November 2012
5
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. Push 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.
10. Raise the travel indicator disk to the stem connector (for sizes 40 through 70). For all sizes, thread the stem
locknuts against the stem connector.
11. 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.
12. Check the valve travel to be sure that the valve travels fully with no overtravel.
Reverse-Acting (Push-Down-to-Open) Valves
See figure 1.
1. Screw the stem locknuts all the way onto the valve stem. Put the travel indicator disk (not used with the size 80
actuator) on the stem locknuts. The concave side of the disk should face the valve.
2. Push the valve stem down to open the valve.
3. Lift or hoist the actuator onto the valve bonnet.
4. Insert the cap screws and tighten the hex nuts (not shown), securing the actuator to the bonnet. Tighten the cap
screws to the torque shown in table 5.
5. Apply actuator loading pressure until the actuator is at the full down position.
6. With the travel indicator scale attached to the actuator yoke, make a temporary mark on the actuator stem at a
point parallel with the bottom mark on the travel indicator scale. This is the fully open position.
7. Refer to the actuator nameplate to determine the bench set pressure range of the actuator. Apply the lower bench
set pressure to the actuator. Turn the spring adjustor until the actuator stem mark is even with the top mark on the
travel indicator scale.
8. Apply the higher bench set pressure to the actuator and verify that the mark on the actuator stem is even with the
bottom mark on the travel indicator scale. This is the fully-open position. The distance from the top mark on the
scale to the bottom mark is equal to the travel of the valve.
If the marks are in line, the actuator is properly bench set.
If the marks are not in line, the spring is not correct for the specified bench set. It is necessary to use a different spring
or a different bench set.
WARNING
To avoid personal injury due to the sudden uncontrolled movement of parts, do not loosen the cap screws when the stem
connector has spring or loading pressure force applied to it.
