Actuator Removal; 685Se Seal And O-Ring Replacement - Fisher 685SE Instructions Manual

685SE/685SR Piston Actuator
June 2017
WARNING
The outer and inner spring cartridge (keys 23 and 57) contains a spring under compression. Do NOT attempt to dismantle
any part of the spring cartridge without first consulting your local
personal injury.
Instructions are given below for complete disassembly of the actuator, seal replacement, and O­ring replacement. When
inspection or repair is necessary, disassemble the actuator only as far as is required to accomplish the job. Key numbers
referenced in the following steps are shown in figures 3, 4, 5, and 6.

Actuator Removal

The following procedure is for the removal of the actuator from a valve.
For 685SE actuators only: It may be necessary to apply a temporary loading pressure to the bottom cylinder pressure
connection to move the piston rod away from the valve stem during removal. If it is not possible to provide a
temporary loading pressure, exercise caution when removing the actuator to prevent damage to the valve stem or
piston rod.
1. Disconnect the actuator tubing from the pressure connections on the upper/lower head and outer spring cartridge
(keys 1/9 and 23) and positioner.
Note
Refer to the appropriate instruction manual for any maintenance or adjustments that need to be made on the positioner.
WARNING
To avoid personal injury due to the sudden uncontrolled movement of parts, do not loosen the stem connector hex nuts
when the stem connector has spring force applied to it.
2. Break the stem connection by removing hex nuts (key 62), studs (key 63) and lock washers (key 10) from the stem
connector (key 18).
3. Depending on the yoke boss size, there is either a yoke locknut or bonnet­to­actuator bolting securing the actuator
to the valve bonnet. Remove whichever is present.
4. For 685SE Actuators: Using the lifting points along the outside perimeter of the outer spring cartridge (key 23),
attach appropriate rigging gear to both lifting points and lift the actuator away from the valve bonnet and stem.
For 685SR Actuators: Thread two lifting eyes into the free ports on the upper head (key 1) 180 degrees apart.
Reference tables 4 and 5 for approximate weights of the actuator to select an appropriate lifting eye. Attach
appropriate rigging gear to both lifting eyes and lift the actuator away from the valve bonnet and stem.
5. Refer to the Actuator Mounting section of this manual for instructions on mounting and installing the actuator onto
a valve.
685SE Seal and O­ring Replacement
The following procedure is for the replacement of the internal piston seals, bearing seals, and O­rings.
10
Emerson sales office or Local Business Partner to avoid
Instruction Manual
D103799X012