Actuator Mounting; Direct-Acting (Push-Down-To-Close) Valves - Emerson FISHER 657NS Instruction Manual

657NS Actuator
November 2012
The control valve assembly normally may be installed in any orientation; however, the assembly must not be installed
so that water can collect in the actuator yoke and lower diaphragm casing areas.
Note
The 657NS actuator will not mount on a standard valve bonnet; it requires a style NS bonnet having eight bonnet-to-yoke stud
bolts.
If the actuator and control valve body are separate, mount the 657NS actuator on the valve body by following the
procedures in the Actuator Mounting section of this manual.

Actuator Mounting

Direct-Acting (Push-Down-to-Close) 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 close 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. Thread the spring adjustor (see figure 1 for sizes 40 through 70 and key 12, figure 4 for size 80) until the actuator is
at the full up 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 top 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, and 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. Verify that the mark on the actuator stem is even with the
bottom mark on the travel indicator scale. This is the fully closed 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.
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.
4
Instruction Manual
D102602X012