Fisher 685SE Instructions Manual page 11

Instruction Manual
D103799X012
1. Remove the lower head (key 9) from the yoke (key 21) by removing hex head cap screws (key 20) and lock washers
(key 10).
2. Loosen tie bolt hex nuts (key 11) in a crisscross pattern. Remove tie rod hex nuts and lock washers (key 10).
3. Remove lower head (key 9) from cylinder (key 4) and place the O­ring side down onto wooden blocks or other
material that will not scratch or gouge the lower head.
4. Extract bearing assembly (keys 12, 13, 14, and 15) from lower head (key 9) by removing the bearing retaining ring
(key 16).
5. Remove the piston wiper seal (key 15), O­ring (key 13), and quad seal (key12) from the bearing (key 14).
6. Clean bearing (key 14) with a light degreaser, if needed.
7. Lightly grease the new O­ring (key 13) and quad seal (key 12), then install onto bearing (key 14). Without grease,
install a new piston wiper seal (key 15) onto the bearing.
8. Reinstall bearing assembly (keys 12, 13, 14, and 15) into lower head (key 9) and secure in place with the bearing
retaining ring (key 16).
9. Remove the O­ring (key 2) from the lower head (key 9) and clean the groove with a light degreaser.
10. Lightly grease the new O­ring (key 2) and install on lower head (key 9).
11. Remove tie bolts (key 3) from upper head (key 1).
12. Lift piston assembly (keys 5, 6, 7, 17, and 19) out from cylinder (key 4) and place on a flat surface.
13. Remove the wear ring (key 6) and quad seal (key 7) from the piston (key 5).
14. Thread locking compound is applied to the threads by the manufacturer during initial assembly. As a result,
disassembly will require heating to loosen the thread locking compound. To remove the piston rod O­ring (key
19), heat the piston assembly using a torch and unthread the piston rod (key 17) from the piston (key 5).
15. After the piston rod (key 17) has completely cooled, remove the piston rod O­ring (key 19). Clean the piston rod
O­ring groove with a light degreaser. Lightly grease a new piston rod O­ring and install onto the piston rod.
16. Reinstall piston rod (key 17) onto piston (key 5) using thread locking compound.
17. Clean piston seal grooves. Install new lightly greased quad seal (key 7) onto piston (key 5).
18. Without grease, trim to length and then install a new wear ring (key 6).
19. Lift cylinder (key 4) vertically and place on a flat surface. Take extra precaution to avoid scratching or gouging the
inner diameter of the cylinder.
20. Remove O­ring (key 2) from the upper head (key 1) and clean the seal groove. Install lightly greased new O­ring
into upper head seal groove.
21. Install cylinder (key 4) onto upper head (key 1), making sure the O­ring (key 2) does not move out of its groove.
22. Carefully install the piston assembly (keys 5, 6, 7, 17, and 19) into cylinder (key 4), making sure all seals and
O­rings stay in place on the outside diameter of the piston (key 5).
23. Install tie bolts (key 3) into upper head (key 1).
24. Carefully install lower head (key 9) onto cylinder (key 4), taking care not to damage threads on the tie bolts
(key 3). Be sure the O­ring (key 2) is in place during this step.
25. Install lock washers (key 10) and tie bolt hex nuts (key 11) onto tie bolts (key 4). Torque in a crisscross pattern
according to table 8.
26. Refer to the Actuator Mounting section of this manual for instructions on mounting and installing the actuator
onto a valve.
685SE/685SR Piston Actuator
June 2017
11