Level Transmitter Troubleshooting and Calibration Guide
Accurate level measurement depends on proper calibration and timely troubleshooting. This guide covers calibration procedures and common level transmitter problems.
I. Calibration Procedures
Differential Pressure Transmitter Calibration
- Isolate the transmitter from the process using the manifold valves
- Vent both high and low pressure sides to atmosphere for zero check
- Apply a known pressure corresponding to the full-scale level using a pressure calibrator
- Adjust the span trim until the output matches the reference
- Verify linearity at intermediate points
- Return the transmitter to service following proper manifold valve sequence
Radar/Ultrasonic Transmitter Calibration
- Verify the empty distance measurement with no product in the tank
- Fill to a known level and verify the distance measurement
- Adjust the speed-of-sound compensation (ultrasonic) if the vapor space temperature differs significantly from ambient
- Suppress false echoes from tank internals using the echo suppression function
II. Common Problems
Level Reading Incorrect: Check tank geometry configuration. Verify that the process fluid density (DP) or dielectric constant (radar/capacitance) has not changed.
Level Reading Fluctuates: Increase damping. Check for turbulence or agitation near the sensor. Install a stilling well if necessary.
Loss of Echo (Radar/Ultrasonic): Check for foam, heavy vapor condensation, or antenna contamination. Increase the transmitted pulse strength if supported.
