Instruction Manual
D102602X012
657NS Actuator
November 2012
12
8. After the last bolt is tightened to 27 N
S
m (20 lbf
S
ft), all of the bolts should be tightened again to 27 N
S
m (20 lbf
S
ft)
in a circular pattern around the bolt circle.
9. Once completed, no more tightening is recommended.
10. Replace the tubing or piping to the top of the upper diaphragm casing.
Size 80 Actuators
The elastomeric parts in a size 80 actuator include the diaphragm and O-rings. Since replacement of these parts
necessitates complete disassembly, perform the steps outlined in Size 80 Actuators, disassembly and assembly
procedures.
Disassembly
Size 40, 45, and 70 Actuators
Key number references are shown in figure 2 for size 40 and 45 actuators and in figure 3 for size 70 actuators.
1. Isolate the control valve from the line pressure, release pressure from both sides of the valve body, and drain the
process media from both sides of the valve. Reduce the actuator loading pressure to atmospheric pressure, and
remove the tubing or piping from the top of the upper diaphragm casing (key 1).
2. To aid in assembly, record the position of the spring adjusting screw (key 12) relative to the actuator yoke (key 9).
Loosen the spring adjusting screw locking set screw (key 67), and thread the adjusting screw out of the yoke until all
spring compression is relieved.
3. If necessary, remove the actuator from the valve body by separating the stem connector (key 26) and removing the
eight bonnet stud bolt nuts. Separate the stem connector by loosening the stem hex nuts (keys 15 and 16) and
unscrewing the two cap screws.
4. Remove the diaphragm casing cap screws and nuts (keys 22 and 23), and lift off the upper diaphragm casing (key
1).
5. Take out the molded diaphragm (key 2).
6. The diaphragm plate and actuator stem (keys 4 and 10) can be taken out of the yoke as an assembly. This assembly
can be further disassembled, if desired, by removing the cap screw (key 3).
7. Take out the actuator spring (key 6) and the lower spring seat (key 11).
8. The lower diaphragm casing (key 5) can be removed from the yoke, if required, by removing the cap screws (key 8)
that hold the lower diaphragm casing in place.
9. Unscrew the adjusting screw (key 12) from the yoke to complete the disassembly. Be careful not to lose the straight
pin (key 89) since it could drop out of the yoke through the threaded adjusting screw hole.
Size 80 Actuators
Key number references are shown in figure 4.
1. Bypass the control valve. Reduce the actuator loading pressure to atmospheric pressure, and remove the piping or
tubing from the upper diaphragm casing connection.
2. Loosen the hex nut (key 50), and back the adjustable travel stop (key 34) away from the diaphragm casings (keys 1
and 5).
3. Unbolt the cap screws (key 8), and remove the spring case assembly (key 35).
4. Measure and record how much of the actuator stem (key 10) extends past the spring adjusting screw (key 12).
Using a hammer and a punch, loosen the spring adjusting screw locknut (key 91). Slip a 12.7 mm (1/2-inch)
