Actuator Mounting; Loading Connection; Adjustments; Travel - Fisher 657 Sizes 80 Instruction Manual

When an actuator and valve body are shipped togeth-
er, the actuator is normally mounted on the valve. Fol -
low the valve body instructions when installing the
control valve in the pipeline. If the actuator is shipped
separately or if it is necessary to mount the actuator
on the valve, perform the Actuator Mounting proce-
dures as described below.
For information on mounting valve positioners, refer to
the appropriate valve positioner instruction manual.

Actuator Mounting

1. To permit adjustment of the actuator spring, the
size 100 actuator must be installed in a vertical posi -
tion above the valve body. Mount the actuator on the
valve bonnet. Insert the cap screws, and tighten the
hex nuts, securing the actuator to the bonnet.
2. Screw valve stem locknuts (key 16, figure 5) all the
way onto valve stem thread.
3. Connect an air supply to the diaphragm casing.
4. For push-down-to-close valves, be sure the valve
plug is on its seat. apply pressure to ensure that the
actuator stem is fully extended. Reduce actuator load-
ing pressure to retract the stem approximately 1/8 inch
(3.2 mm).
5. For push-down-to-open valves, move valve plug to
closed position. On large body sizes, this may require
the use of a pry bar inserted through the body line
opening. If the body is installed in a pipeline, the bot -
tom flange (if one is used) can be removed and the
valve plug pushed to the seat from the bottom open-
ing. Pressure the actuator to move the stem out 1/8
inch (3.2 mm).
WARNING
To avoid personal injury due to the sud-
den uncontrolled movement of parts, do
not loosen the stem connector cap
screws when the stem connector has
spring or loading pressure force applied
to it.
CAUTION
Incomplete engagement of both valve
stem and actuator stem in the stem con-
nector 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.
Type 657 Sizes 80 & 100
12B6508-A / DOC
Figure 3. Type 657 Actuator Nameplate
6. Clamp the actuator and valve plug stems between
the two stem connector halves (key 26, figure 5). In-
sert and tighten the stem connector cap screws.
7. Thread the stem locknuts against the stem connec-
tor.
8. Align the travel indicator scale (key 18, figures 5
and 6) to show valve position.

Loading Connection

1. Connect the loading pressure piping to the connec-
tion in the top of the diaphragm casing.
2. Remove the 1/4-inch bushing (key 33, figure 5 and
key 120, figure 6) to increase connection size, if nec-
essary. The connection can be made with either piping
or tubing.
3. Keep the length of tubing or piping as short as pos-
sible to avoid transmission lag in the control signal. If
an accessory (such as a volume booster or valve posi-
tioner) is used, be sure that the accessory is properly
connected to the actuator. Refer to the positioner in-
struction 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 dia-
phragm.
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.

Adjustments

Travel

Make travel adjustments when the motion observed
during actuator travel is different from the travel
stamped on the actuator nameplate (figure 3). 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 a slight pressure on the actuator
diaphragm. This moves the valve plug off the seat,
reducing the chance of damaging the valve plug or
seat during adjustments.
3