Fisher 657 - Manual (Page 7)

Instruction Manual
D100307X012
657 Size 80 and 100 Actuators
December 2010
7
tools away from the spring and spring seat, slowly decrease loading pressure until the spring force holds the spacers
firmly between the spring seat and lower diaphragm casing (key 5, figure 5).
5. Loosen the jam nut. The adjusting nut can now be rotated clockwise (when viewed from the diaphragm casings) to
increase the loading pressure required to start actuator stem travel or counterclockwise to decrease the pressure
required to start travel.
6. Pressure the actuator to move the spring seat away from the spacers, and carefully remove the spacers.
7. If the total adjustment required was greater than valve travel, repeat the procedure. It will be necessary to make
new spacers using the new dimension B and the remaining adjustment required or valve travel, whichever is less.
Tighten the jam nut when adjustment is complete.
Maintenance
WARNING
Avoid personal injury or property damage from sudden release of process pressure or bursting of parts. 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
from both sides of the valve. Drain the process media from both sides of the valve.
D Vent the power actuator loading pressure and relieve any actuator spring precompression.
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.
The maintenance instructions are divided into four sections: actuator (sizes 80 and 100); side‐mounted handwheel
assembly (manual operator); hydraulic snubber; and top‐mounted handwheel assembly (adjustable‐up travel stop).
Actuator
This procedure describes how the actuator can be completely disassembled and assembled. When inspection or
repairs are required, disassemble only those parts necessary to accomplish the job; then, start the assembly at the
appropriate step.
Key numbers refer to figure 4 for size 80 actuators and figure 5 for size 100 actuators.
Size 80 Disassembly
1. Bypass the control valve. Reduce the loading pressure to atmospheric, and remove the tubing or piping from the
top of the diaphragm casing (key 1).