Fisher A41 Instruction Manual page 20

1. Isolate the control valve from line pressure, and relieve pressure from the valve body. Shut off and disconnect all
lines from the power actuator.
WARNING
The edges of a rotating disc have a shearing effect that may result in personal injury. To help prevent such injury, stay clear
of the disc edges when rotating the disc (key 3).
CAUTION
Damage to the disc (key 3) may occur if the disc is not closed when the valve is being removed from the pipeline. If
necessary, pressure the actuator temporarily to retain the disc in the closed position while removing the valve from the
pipeline.
2. Unscrew the flange bolts, and remove the valve from the pipeline.
3. Unscrew the machine screws (key 8), and remove the seal retainer (key 2). Also remove the retainer clip (key 34).
4. Remove the seal ring or seal ring assembly (key 4). The spring (key 5) is removed with a PTFE seal ring.
5. For S31600 stainless steel seal ring assemblies, replace the gaskets (key 4C) if the entire seal ring assembly is not
replaced. Scrape off the old gaskets from both sides of the seal ring and the seal ring sides of the valve body (key 1)
and seal retainer. Clean the gasket surfaces.
6. Reconnect or mount the actuator (if it was removed) before proceeding.
For an actuator with adjustable travel, also adjust the actuator before proceeding. This is necessary due to the
measurements that must be made during the actuator adjustment process.
Refer to the Actuator Mounting section of this manual and to the separate actuator instruction manual for mounting
and adjusting instructions.
7. The valve should be closed during seal ring installation to permit accurate centering of the seal. To install the new
seal ring:
For a PTFE seal, if the spring (key 5) was disassembled, hook the spring ends together. Work the spring into the recess
in the seal ring (key 4). Install the seal ring and spring assembly into the recess in the valve body as shown in figure 13.
For a complete S31600 stainless steel seal ring assembly, install the seal ring assembly as shown in figure 13.
8. For an S31600 stainless steel seal ring on which the gaskets will be replaced, lay the following parts down in order so
that they are accurately centered on the valve: one new gasket; the seal ring oriented as shown in figure 13; and the
second new gasket.
9. Attach the seal retainer and, if used, the retainer clips and washers to the valve body and secure with the machine
screws. Tighten the machine screws evenly so as not to crack or break the S31600 stainless steel seal ring gaskets, if
used.
Be certain the disc is closed before installing the valve according to the Installation section of this instruction manual.
Disc, Drive Shaft, and Bearing Maintenance for NPS 3 through 12
This procedure is to be performed when replacing the valve disc, drive shaft, taper pins, hollow pins, and bearings due
to wear or damage to one or more component parts.
Part locations and key numbers are shown in figures 9 and 11 unless otherwise noted.
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