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Vortex and Ultrasonic Flowmeter Fault Finding Guide

A one page guide to vortex and ultrasonic meter problems: low Reynolds number, vibration, signal quality, pipe data and installation.

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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
Vortex reads zero at low flow	Below minimum velocity or Reynolds number, cutoff high	Check sizing; consider smaller meter; review cutoff
Vortex reads with no flow	Pipe vibration counted as vortices	Adjust filter or trigger level; improve supports
Vortex reads low	Wrong K factor or ID, two phase flow, short straight run	Check configuration; check process; straight run
Ultrasonic no signal	Air, solids, poor coupling, wrong spacing	Recouple sensors; check spacing and pipe data
Ultrasonic reads wrong	Wrong pipe OD, wall, material or liner	Measure wall thickness; correct pipe data
Ultrasonic unstable	Short straight run, partly full pipe	Move sensors; check fill; use two paths

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

Why does a vortex meter stop at low flow?

Vortices become weak below a minimum Reynolds number, so the meter cuts off.

Why does a clamp on meter need wall thickness?

It calculates the sound path and flow area from pipe dimensions.

Can vibration cause false flow?

Yes, on vortex meters.

Types of flow meters

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