Troubleshooting Guides · Free Tool

Magnetic Flowmeter Fault Finder

Choose what the electromagnetic flowmeter is showing and get the likely causes with checks and fixes.

Empty pipe alarmNoisy readingZero offsetWrong value

What do you see?

SymptomEmpty pipe alarm with a full pipe

Most likely causeElectrode coating

First checkCheck electrode resistance or coating diagnostics

Causes in order of likelihood

Cause	How to check	Fix
Electrode coating	Check electrode resistance or coating diagnostics	Clean electrodes; consider an electrode cleaning option
Empty pipe detection set too sensitive	Check the empty pipe setting and conductivity	Adjust the empty pipe threshold
Air at the top of a horizontal pipe	Check meter position (high point?)	Relocate to a low point or vertical upward flow

Before You Start

Work under a permit, inform the control room and put the loop in manual or bypass the trip before touching a live instrument.
Read the transmitter diagnostics and alarm history.
Confirm the pipe is full at the meter location.
Check grounding: grounding rings or electrodes connected to the pipe.

Magnetic Flowmeter Fault Finder: All Symptoms

Empty pipe alarm with a full pipe

Likely cause	How to check	Fix
Electrode coating	Check electrode resistance or coating diagnostics	Clean electrodes; consider an electrode cleaning option
Empty pipe detection set too sensitive	Check the empty pipe setting and conductivity	Adjust the empty pipe threshold
Air at the top of a horizontal pipe	Check meter position (high point?)	Relocate to a low point or vertical upward flow

Noisy or unstable flow

Likely cause	How to check	Fix
Poor grounding	Check grounding rings, straps and pipe lining	Install grounding rings and straps as per the manual
Air bubbles or solids in the fluid	Check upstream pumps and tanks	Increase back pressure, relocate the meter
Low conductivity fluid	Measure conductivity (should be above the meter minimum, typically 5 µS/cm)	Use a different meter technology

Flow shown at zero flow (zero offset)

Likely cause	How to check	Fix
Fluid moving or convection in a closed pipe	Close upstream and downstream valves and observe	Perform zero adjustment with the pipe full and still
Electrical interference	Check cable separation and screen	Separate from power cables, correct screen earthing
Electrode leakage	Check electrode diagnostics	Repair or replace the sensor

Reading consistently too high or low

Likely cause	How to check	Fix
Wrong sensor calibration factor or pipe size	Compare transmitter settings with the sensor nameplate	Enter the correct calibration factor and size
Partially filled pipe	Check installation and empty pipe status	Ensure the pipe is always full
Liner damage or build up reducing the bore	Inspect the sensor	Clean or repair the liner

Coil or sensor error alarm

Likely cause	How to check	Fix
Damaged coil cable or connection	Measure coil resistance and compare with the factory value	Repair the cable or connection
Water in the terminal box	Inspect the terminal box seals	Dry out, replace seals, fit correct glands
Failed coil	Coil resistance open or shorted	Replace the sensor

Key insight: grounding is the first suspect for any unstable magmeter reading, especially in plastic or lined pipes where the fluid is not grounded through the pipe.