Instruction Manual
D102602X012
657NS Actuator
November 2012
8
Adjustments
Travel
WARNING
When moving the actuator stem with diaphragm loading pressure, use caution to keep hands and tools out of the actuator
stem travel path. Personal injury and/or property damage is possible if something is caught between the actuator stem and
other control valve assembly parts.
Make travel adjustments when the motion observed during actuator travel is different from the travel stamped on the
actuator nameplate. If the Actuator Mounting procedure was followed correctly, this adjustment should not be
necessary.
When adjusting travel of a reverse-acting (push-down-to-open) valve, apply sufficient loading pressure to move the
valve plug off of the seat. This procedure reduces the chance of damaging the valve plug or seat during adjustments.
1. Back the stem locknuts and travel indicator disk away from the stem connector, and slightly loosen the stem
connector cap screws.
CAUTION
Do not use wrenches or other tools directly on the valve stem. Damage to the stem surface and subsequent damage to the
valve packing might result.
2. Tighten the locknuts together using a wrench, then screw the valve stem either into the stem connector to
lengthen travel or out of the stem connector to shorten travel.
3. Cycle the actuator to check the travel. If actual travel is not equal to the specified travel, adjust and check travel
until correct. Tighten the stem connector cap screws when correct travel is obtained.
4. Raise the travel indicator disk by threading the stem locknuts against the stem connector.
Spring
Bench Set
The bench set pressure range is used to adjust the initial compression of the actuator spring with the actuator
assembly “on the bench”. The correct initial compression ensures that the valve-actuator assembly will function
properly when it is put in service and the proper actuator diaphragm operating pressure is applied.
The bench set range is established with the assumption that there is no packing friction. When attempting to adjust
the spring in the field, it is very difficult to ensure that there is no friction being applied by “loose” packing.
Accurate adjustment to the bench set range can be made during the actuator mounting process (see the Actuator
Mounting procedure) by making the adjustment before the actuator is connected to the valve.
