Emerson Fisher 657C Instruction Manual page 8

657C Actuator (40i, 46i, and 60i)
November 2019
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 desuperheater assembly parts.
Also, provide a certified pressure gauge suitable to accurately read the diaphragm pressure from 0 through 0.3 bar (5
psig) above the upper operating range pressure marked on the nameplate. Apply loading pressure to the diaphragm.
CAUTION
Stroke the actuator a few times to ensure that the pressure gauge is working correctly, and that the actuator is functioning
properly. To prevent actuator damage, it is important to ensure that the actuator stem is stroking smoothly and not
exhibiting binding or excessive friction. Binding or excessive friction could be an indicator of incorrect assembly or
damaged parts.
1. If not already accomplished, provide a regulator to apply an adjustable loading pressure to the actuator during
bench set adjustments and a shut-off valve to isolate and prevent the unwanted movement.
2. Set the diaphragm loading pressure at 0 bar (0 psig). Then, slowly raise the pressure towards the lower bench set
pressure, as indicated on the nameplate, while checking for the first linear movement of the actuator stem. The
actuator stem should show movement at the lower bench set pressure. If movement occurs before or after the
lower pressure is reached, adjust the spring adjuster (see figure 5) into or out of the yoke until the actuator stem's
movement is first detected at the lower bench set pressure.
3. Be sure the spring adjuster is adjusted to meet the requirements of step 2 above.
4. Apply the upper bench set pressure, as indicated on the nameplate. This pressure extends the actuator stem down
toward the desuperheater. At the end of the actuator stem, use a marker or a piece of tape to mark the
desuperheater stem (see figure 5).
Note
The actuator stem may slide over the desuperheater stem as shown in figure 5. If the actuator stem does not pass over the
desuperheater stem, provide a method to mark this point of stem travel.
5. Slowly decrease the diaphragm loading pressure to the lower bench set pressure, as indicated on the nameplate.
6. Measure the distance between the marker or tape on the desuperheater stem to the end of the actuator stem. The
distance should match the rated travel indicated on the nameplate.
7. If the measured travel matches the nameplate travel, bench set is complete. Proceed to the Installing the Stem
Connector Assembly subsection.
8. If the measured travel is not exact, consider the spring free-length and spring rate tolerances may produce a slightly
different bench set than specified. Contact your
8
Emerson sales office for assistance.
Instruction Manual
D104496X012