Maintenance; Valve Plug And Seat Ring - Fisher D4 Instruction Manual

D4 Valve
July 2015
Spring‐to‐Close
Refer to figure 4.
1. Loosen the adjusting screw nut (key 44).
2. Turn the adjusting screw (key 31) clockwise to compress the spring or counterclockwise to decrease spring
compression.
3. After adjustment, tighten the adjusting screw nut (key 44).
Spring‐to‐Open
Refer to figure 5.
1. Unscrew the spring case assembly (key 27).
2. Turn the adjusting stem nut (key 44) clockwise to compress the spring or counterclockwise to decrease spring
compression.
3. After adjustment, replace the spring case assembly (key 27).

Maintenance

Refer to figure 4.
Valve parts are subject to normal wear and must be inspected and replaced as necessary. The frequency of inspection
and maintenance depends on the severity of the service conditions.
WARNING
Avoid personal injury 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
on 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.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.

Valve Plug and Seat Ring

The D4 control valve is designed to allow easy access to the valve plug and seat ring without disturbing the packing.
Refer to other sections of this instruction manual if additional maintenance is required.
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Instruction Manual
D103042X012