Seal Ring Maintenance For Nps 3 Through 12 - Fisher A41 Instruction Manual

Clean all accessible metal parts and surfaces to remove particles that would prevent the packing from sealing.
Assembly
Inspect the shaft. If it is damaged, it cannot make a good seal with the packing and it must be replaced. If the leakage
comes from the outside diameter of the packing, it is possible that the leakage is caused by nicks or scratches around
the packing box wall. Inspect the packing box wall for nicks and scratches when performing the following procedures.
If the valve is equipped with the ENVIRO-SEAL packing system, refer to the separate ENVIRO-SEAL Packing System for
Rotary Valves Instruction Manual (D101643X012) for assembly.
Note
Except with oxygen service, lightly lubricate new PTFE V-rings with silicone-base lubricant to aid in assembly.
WARNING
Do not lubricate parts when used in oxygen service, or where the lubrication is incompatible with the process media. Any
use of lubricant can lead to the sudden explosion of media due to the oil/oxygen mixture, causing personal injury or
property damage.
1. Install the new packing parts (see figure 6). Install the packing follower and finger tighten the packing flange nuts
onto the studs only enough to stop leakage.
2. If the valve was equipped with a bonding strap assembly (figure 5), re-install the assembly.
3. Refer to the Actuator Mounting section of this manual. If necessary, refer to the separate actuator instruction
manual for adjustment procedures.
4. When the valve is being placed into operation, check around the packing follower for leakage.
For PTFE-filled or graphite standard packing arrangements covered in this manual, often leakage from the packing can
be stopped by tightening the packing flange nuts just enough to stop the leak.
CAUTION
Use caution when tightening the nuts, overtightening nuts can damage packing box parts and result in increased drive
shaft friction.

Seal Ring Maintenance for NPS 3 through 12

Perform this procedure if the control valve is not shutting off properly (that is, if it is leaking downstream). It is
recommended, but not required, to remove the actuator for easier handling of the valve during the following
procedures.
Key numbers are shown in figure 12 unless otherwise noted.
13