Fisher 657 - Manual (Page 9)

Instruction Manual
D100307X012
657 Size 80 and 100 Actuators
December 2010
9
3. Position the lower spring seat (key 11), and slide the actuator spring (key 6) squarely onto the spring seat.
4. If the diaphragm plate and actuator stem (keys 4 and 10) were separated, fasten them together using the cap
screw (key 3) and tighten to a torque of 544 N Sm (400 lbfSft).
For actuators without a hydraulic snubber, slide upper sleeve (key 34) onto the actuator stem, and then slide upper
sleeve, actuator stem and diaphragm plate into the spring case (key 29) so that the spring (key 6) fits squarely
between the diaphragm plate and the spring seat (key 11).
For actuators with a snubber, thread the actuator stem and upper spring seat (keys 10 and 90) into the piston/piston
rod assembly (key 27). Install the snubber assembly and attached actuator stem into the upper sleeve, spring case
adaptor, and spring case (keys 34, 72, and 29). Secure with cap screws (key 85).
5. Place the diaphragm (key 2) with pattern side facing away from the diaphragm plate (key 4). Align the holes in the
diaphragm and the lower diaphragm casing (key 5).
6. Position the upper diaphragm casing (key 1) on the diaphragm (key 2), and align the holes.
Note
When you replace actuator diaphragms in the field, take care to ensure the diaphragm casing bolts are tightened to the proper
load to prevent leakage, but not crush the material. Perform the following tightening sequence with a manual torque wrench for
size 80 and 100 actuators.
CAUTION
Over‐tightening the diaphragm casing cap screws and nuts can damage the diaphragm. Do not exceed the following
maximum torque values for the appropriate diaphragm material:
EPDM/Meta‐Aramid: 95 N Sm (70 lbfSft) Nitrile, Silicone, FKM (fluorocarbon)/Meta‐Aramid: 68 NSm (50 lbfSft)
Table 2. Maximum Torque Values
DIAPHRAGM MATERIAL
INITIAL TORQUE
N Sm (lbfSft)
FINAL TORQUE
N Sm (lbfSft)
EPDM/Meta‐Aramid 41 (30) 82, +/-13 (60, +/-10)
Nitrile, Silicone, FKM/Meta‐Aramid 34 (25) 68 (50)
Note
Do not use lubricant on these bolts and nuts. Fasteners must be clean and dry.
7. Insert the cap screws (key 22) into the diaphragm casing, and tighten the hex nuts (key 23) in the following
manner. The first four hex nuts tightened should be diametrically opposed and 90 degrees apart. Tighten these four
hex nuts to the initial torque value found in table 2 for the diaphragm material being used.
8. Tighten the remaining hex nuts in a clockwise, criss‐cross pattern to the initial torque value found in table 2 for the
diaphragm material being used.
9. Repeat this procedure by tightening four hex nuts, diametrically opposed and 90 degrees apart, to the final torque
value that is specified in table 2 for the diaphragm material being used.