Fisher 9500 - Manual (Page 8)

9500 Valve
Instruction Manual
Form 2433
November 2007
8
Table 4. Troubleshooting Guide
Fault Possible Cause Correction
1. Leakage out sides of
valve (at thrust plates)
between thrust bushings
and shaft. a. Hub seals require adjustment.
b. Taper pins are not sealed.
a. Adjust using Hub Seals portion of Adjustments
procedures.
b. Remove valve from line and re-seat taper pins or install
new taper pins using Maintenance procedures.
2. Leakage out sides of
valve (at thrust plates)
between valve body and
thrust bushings, leakage
at flanges, faces, or both a. Flange gaskets used.
b. Partial O-ring bead on liner faces damaged.
a. Check to see if flange gaskets are being used; if so,
remove gaskets.
b. Replace liner using Maintenance procedures.
3. Leakage through
disc/liner seal a. Hub seals require adjustment.
b. Linkage requires adjustment.
c. Actuator has insufficient torque output to close disc
against pressure drop. (Actuators are selected to have
sufficient torque output to shut off the flow against a
specific pressure drop, not necessarily against the
maximum allowable pressure drop. Be sure that the
pressure drop for which the actuator is selected is not
being exceeded.)
d. Liner has been damaged by flowing medium or other
valve parts damaged by being subjected to service
conditions beyond those for which valve is designed.
a. Adjust seals using Hub Seals portion of Adjustments
procedures.
b. Refer to Linkage portion of Adjustments procedures.
c. If possible, check shutoff at lower pressure drops. If
shutoff is obtained at low pressure drops, but actuator
stalls and does not produce full disc rotation at service
pressure drop, actuator output torque is too low. For piston
actuators, it may be possible to increase output torque by
increasing supply pressure. Do not exceed maximum
allowable supply pressure of actuator.
d. Inspect and replace parts using Maintenance
procedures.
4. Valve shaft will not
rotate a. If actuator does not stall, but shaft does not rotate, the
spline teeth on the valve shaft are sheared.
b. If actuator stalls, shaft is binding in bushings due to
linkage misalignment caused by excessive wear of linkage
parts.
c. If actuator stalls and linkage is not misaligned, actuator
may have insufficient output torque to rotate disc against
flow.
a. Refer to the actuator instruction manual to remove
actuator cover plate. Replace valve shaft using
Maintenance procedures if spline teeth are sheared.
b. Replace linkage parts.
c. Check actuator operation with no pressure applied to
the valve. If valve now functions properly, actuator is too
small.
5. Valve shaft rotates, but
valve does not control
process fluid Taper pins (or drive shaft spline for coated-disc
constructions) have been sheared due to obstruction to
disc rotation or other internal parts damaged by being
subjected to service conditions beyond those for which the
valve was designed. Inspect and replace parts using the Maintenance
procedures.
5. If taper pin (key 15) ends are peened, grind off
the peened portions. Driving from the smaller end of
the pins, drive the pins out of the disc (key 3) and
shaft (key 4).
WARNING
Once the shaft has been removed, the
disc may fall from the valve body,
causing personal injury or disc
damage. Support the disc before
removing the shaft.
6. Pull the shaft out of the valve body. If the shaft
cannot be pulled from the valve body, drive the shaft
out but use care to avoid upsetting the end of the
shaft.
7. Remove the disc from the valve body.
8. Remove the liner (key 2) from the valve body.
Some Type 9500 valves have the liner bonded to the
valve body. If the valve has a bonded liner, burn or
chip out the liner.
To strip the liner out with solvent, use Dynasolve
185, or equivalent solvent. (Dynasolve is a product
of DYNALOY
t Inc.). Cover the valve with solvent
bath or enclose the solvent bath around the liner.
Remove all adhesive after the liner has been
removed.