GE Masoneilan 4700E, Maintenance Manual

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Masoneilan 4700P/E & 4800P/E Positioners Manual =
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Troubleshooting
The following conditions must exist to ensure satisfactory operation of the positioner:
The valve must be properly mounted in the line so that the actuator counters
the dynamic torque and the valve operates as desired on air failure.
Supply pressure is adequate for valve operation. See pressure drop tables in
valve catalog.
Correct positioner installation.
Correct positioning of the feedback (cam, bearing lever, etc.).
Proper cam selection.
Supply, instrument signal and output connections must be correct for the
positioner action (i.e., direct or reverse).
Air tight connections.
Correct position of the bypass.
In case of malfunction, check following in order given:
1. Check zero adjustment and adjust the zero nut (4B) if necessary. Lock with locknut
(4C).
2. Check span adjustment and adjust if necessary.
3. Adjust instrument signal pressure from minimum to maximum and observe the
corresponding gauge. If Instrument gauge reading does not respond to the signal,
the diaphragm S/A may be broken. Replace the defective part.
4. Positioner insensitivity may be the result of a sticking pilot spool whose movement
may be impeded by:
a. Foreign matter such as dirt, metal particles, etc.
b. Partial blockage of air passages caused by too much oil in the air lines.
c. Blocking of vent holes.