Maintenance - Fisher 685 Instruction Manual

685 Piston Actuator
June 2017
Figure 2. Engage Pin Control Knob Operation
OVERRIDE
ENGAGE
PIN (Key 38)
S28909

Maintenance

WARNING
Avoid personal injury from sudden release of process pressure. Before performing any maintenance operations:
D Do not remove the actuator from the valve while the valve is still pressurized.
D Always wear protective gloves, clothing, and eyewear when performing any maintenance operations to avoid personal
injury.
D Disconnect any operating lines providing air pressure, electric power, or a control signal to the actuator. Be sure the
actuator cannot suddenly open or close the valve.
D Use bypass valves or completely shut off the process to isolate the valve from process pressure. Relieve process pressure
on both sides of the valve. Drain the process media from both sides of the valve.
D Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
D The valve packing box may contain process fluids that are pressurized, even when the valve has been removed from the
pipeline. Process fluids may spray out under pressure when removing the packing hardware or packing rings, or when
loosening the packing box pipe plug.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
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 and 4.
8
PULL PIN (TO LOCK OVERRIDE
ENGAGE PIN INTO PLACE)
DISENGAGED
POSITION
Instruction Manual
ENGAGED
POSITION
D103626X012
ENGAGE PIN
CONTROL
KNOB (Key 33)