Loading Connections - Fisher 655 Instruction Manual

Type 655 and 655R
g. Lower the actuator onto the valve body bonnet,
and tighten the yoke locknut.
h. Stroke the actuator, and measure the stem
movement to check travel. If the movement is more
than full travel, turn the valve stem into the actuator
stem the amount of over-travel. If the movement is
less than full travel, turn the valve stem out of the
actuator stem the amount of under-travel.
3. After correct travel has been obtained, tighten the
hex nuts (key 12) against the actuator stem (key 8),
and tighten the yoke locknut with a hammer and
punch.
Changing the spring adjustment will not
change the actuator pressure range for
that particular spring (see table 2).
Changing the spring adjustment merely
shifts the position of the spring either
up or down so that valve travel can
coincide with the actuator pressure set-
ting range.
4. While monitoring loading pressure with a pressure
gauge, stroke the actuator, and then turn the adjusting
screw until the valve begins to travel at the desired
pressure. Turn the adjusting screw out of the yoke to
decrease spring compression and thus allow the valve
to begin travel at a lower loading pressure. Turn the
adjusting screw into the yoke to increase spring com-
pression and thus allow the valve to begin travel at a
higher loading pressure.

Loading Connections

Install the control line following the steps listed below.
Typical installations are shown in figure 3.
1. Connect the control line into either the upstream
pipeline for pressure-relief service or into the down-
stream pipeline for pressure-reducing service as
shown in figure 3. Make the pipeline tap at least four
to eight pipe diameters away from the regulator or re-
lief valve, or any elbow, swage, or nipple, to avoid ab-
normal velocities or turbulence.
2. Connect the other end of the control line to the
1/2-inch NPT connection in the center of the upper
diaphragm casing (key 1) or to the connection in the
handwheel body (key 28, figures 6 and 7; key 142,
figure 8).
3. Fit the control line with a large-port needle valve.
Partially closing or throttling this valve will tend to
dampen any cycling or pulsating action of the regula-
tor. Never completely close the needle valve while the
regulator is in operation.
6
Note
Startup
The procedures for placing into operation and adjust-
ing the equipment for both pressure-reducing and
pressure-relief applications are described below. Typi-
cal installation schematics are shown in figure 3.
Startup For Pressure-Reducing Service
1. Open the needle valve in the control line.
2. Open the downstream shutoff valve.
3. Close the valve in the bypass line.
4. Slowly open the upstream shutoff valve.
Startup For Pressure-Relief Service
1. Open the needle valve in the control line.
2. Open the downstream shutoff valve.
3. Slowly open the upstream shutoff valve.
4. Close the valve in the bypass line.
Adjustment For Pressure-Reducing or
Pressure-Relief Service
The actuator is factory-set as specified on the order,
and the pressure range is stamped on the nameplate
(figure 2). If a pressure setting other than the one spe-
cified is desired, change the pressure setting by fol-
lowing the procedures listed below. Be sure to change
the nameplate to indicate the new pressure setting.
The new pressure setting must not exceed the limits
given in tables 1 and 2 or in any applicable codes.
CAUTION
To protect equipment in the process
system from a sudden release of pres-
sure, always use a pressure gauge to
monitor pressure when making adjust-
ments.
To adjust the downstream pressure setting for pres-
sure-reducing service, or the upstream pressure set-
ting for pressure-relief service, proceed as follows. To
decrease the pressure setting, turn the adjusting
screw (key 10, figure 5) clockwise; to increase the
pressure setting, turn the adjusting screw counter-
clockwise. If the spring does not provide the required
pressure setting, replace it through the following steps:
1. Disassemble the actuator by following steps 1, 3
and 4 of the Disassembly portion of the Maintenance
section.
2. Remove the diaphragm (key 2). Then, unscrew the
cap screw (key 3), and lift the diaphragm plate (key 4)
out of the actuator body.