Cashco 988-MB - Manual (Page 16)

16 IOM-988/989-BODY
VII. TROUBLE SHOOTING GUIDE
1. Valve is “jumpy” in stroking.
SECTION VII
Possible Cause Remedy
A. Excess packing friction. A1.
A2.
A3.
A4. Realign body–stem–actuator.
Packing follower too tight for optional packing designs.
Install positioner.
Increase bench set by changing to stiffer actuator range spring.
Will require positioner if not installed. May require different air-
set.
B. Installed backwards. B. Install per fl ow arrow.
2. Valve makes “screeching” noise.
Possible Cause Remedy
A. Excess pressure drop. A. Bring pressure drop within design limits.
B. Lower guide bushing wear. B. Replace upper and lower guide bushings.
C. Misalignment. C. Realign body–stem–actuator.
3. Valve exhibits “excess” vibration.
Possible Cause Remedy
A. Excess pressure drop. A. Bring pressure drop within design limits.
B. Lower guide bushing wear. B. Replace upper and lower guide bushings.
C. Excessive cavitation in liquid service. C1.
C2. Change operation parameters to relieve causes of cavitation.
Replace valve with valve equipped for cavitational control.
D. High outlet velocity. D1.
D2.
D3. Reduce fl ow rate and/or pressure drop.
Use multiple valves in series or parallel.
Increase outlet pipe size.
4. Valve exhibits “excess” seat leakage.
Possible Cause Remedy
A. Excess pressure drop. A1.
A2. Reduce pressure drop conditions.
Convert to reduced trim.
B. Improper actuator bench setting. B1.
B2. Calibrate actuator-to-valve.
Ensure proper engagement of actuator stem-to-valve stem.
Adjust as calibration dictates.
C. Metal seat design instead of composition seat
design. C. Convert valve to composition seat design.