Fault Finding Guides · Free PDF

Radar and Ultrasonic Level Fault Finding Guide

A one page guide to non contact level problems: lost echoes, false echoes, foam, condensation, buildup and configuration.

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A one page A4 guide to print for the workshop or keep on your phone in the field. The full content is also shown below.

Symptom	Likely causes	Checks and fixes
Lost echo	Foam, turbulence, low dielectric, antenna buildup	Check echo curve; clean antenna; consider GWR or stilling well
Reads constant level	Locked on a false echo from internals	Redo false echo mapping at low level
Reads full when empty	Echo inside blocking distance, condensation on antenna	Check blocking distance; heat or purge antenna
Jumps between values	Agitator, filling stream, multiple echoes	Move sensor; map; increase damping slightly
Ultrasonic reads wrong in closed tank	Vapour changes speed of sound, temperature gradient	Use radar; check temperature compensation
Offset error	Wrong reference height or tank height	Measure ullage manually; correct reference

Status	Meaning	Action
F Failure	Output invalid	Repair or replace; check loop goes to safe state
C Function check	Simulation, calibration or maintenance active	Finish the work, return to normal mode
S Out of specification	Operating outside limits or uncertain	Check process conditions and sensor
M Maintenance required	Still valid but degrading	Plan maintenance before failure

What is false echo mapping?

Recording fixed echoes from internals so the transmitter ignores them.

Why does foam cause problems?

Foam can absorb or scatter the signal.

When should GWR replace radar?

For foam, low dielectric, chambers and interface measurement.

Guided wave radar vs non contact radar

A practical guide on instrumentationblog.in with more background on this equipment.