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Section 4
Model 351/352/353 Liquid Level Systems
CAUTION:
The sensor bellows can be damaged by contact with the housing.
When installing the sensor assembly, avoid unnecessary contact
with the housing.
Calibration
The actuated instrument is calibrated according to the procedure presented in
the installation and operation manual for that instrument.
IMPORTANT: During calibration, the sensor should be elevated to the exact position it
will occupy in the installa tion. Otherwise, calibration pressures must be
modified to compensate for the differences in hydro static pressures.
Troubleshooting
Troubleshooting procedures for the actuated instrument are presented in the
technical manual for that instru ment.
Troubleshooting procedures for the sensor are presented in Table 4.2.
Table 4.2—Sensor Troubleshooting Chart
Problem
Probable Cause
Corrective Action
Transmitter reading off zero
(±1%) with empty tank.
Minor elevation errors.
Re-zero transmitter according
to actuated instrument
technical manual.
Transmitter reading off zero
(exceeds ±1%).
Elevations of sensors (or
transmitter) are incorrect.
Raise/lower upper sensor.
Raise/lower transmitter (single
sensor system).
Transmitter remains at full-
scale.
Sensors are reversed.
Reinstall sensors, HP sensor
to top of tank.
Transmitter does not respond
to level changes.
Sensors contaminated.
Capillary tubing closed.
Transmitter inoperative.
Clean sensors carefully.
Replace tube.
Replace parts, see actuated
instrument technical manual.
Transmitter is slow or erratic.
Sensors contaminated.
Capillary tubing closed.
Clean sensors carefully.
Open or replace.
Transmitter drifts.
Leak in sealed system.
Repair.
