
TROUBLESHOOTING
Issue Possible Cause Remedy
Meter indicates higher flow than actual. Cavitation. Increase back pressure.
Meter indicates high flow. Dirt blocking flow area rotor. Clean meter; add filter.
Meter indicates low flow. Dirt dragging rotor. Clean meter; add filter.
Meter indicates low flow. Worn bearing. Replace bearing; recalibrate when
required.
Meter indicates low flow. Viscosity higher than calibrated. Change temperature; change fluid;
recalibrate meter.
Erratic system indication; meter alone
works well.
Ground loop is shielding. Ground shield one place only. Watch for
internal electronic instrument grounds.
Indicator shows flow when shut off.
Mechanical vibration causes rotor to
oscillate without turning.
Mechanical vibration. Isolate meter; use potted pickoff.
No flow indication. Full flow of fluid
opened into dry meter. Impact of fluid
on rotor causes bearing separation.
Fluid shock. New bearing failed. Move meter to position where it is full
of fluid at start-up.
Erratic indication at low flow; good
indication at high flow.
Low instrument sensitivity. 10
mV rms turbine signal is being
lowered by loading of electronics or
instrumentation cannot sense low level
signals.
Amplify signal.
No flow indication. Faulty pickoff. Replace pickoff; recalibrate as
necessary.
System works perfectly, except
indicates lower flow over entire range.
Bypass flow, leak. Eliminate bypass valves, leak. Faulty
solenoid valves.
Meter indicating high flow. Upstream
piping at meter smaller than meter.
Fluid jet impingement on rotor. Critical
in gas.
Change piping.
Opposite effects as above. Viscosity lower than calibrated. Change temperature; change fluid;
recalibrate meter.
Mass flow indication wrong. Turbine
meter is volumetric; density correction
is electronic; must change with
temperature.
Wrong fluid density. Critical in gas. Check fluid, electronics.
Erratic or wrong indication of flow. Loose pickoff. Tighten pickoff.
Indicates high flow two hours after
installing new bearing.
Bearing wear-in; small meters critical. Recalibrate. 20…30 min. run-in is
required to stabilize friction.
Cannot reach maximum flow rate;
meter selection was with Delta-P at 0.75
sp. gr., now using on 1.0 sp. gr. Delta-P
is proportional to specific gravity.
High pressure drop. Install larger meter.
Does not repeat at low flows. Repeats at
high flows.
System resolution readability. Increase resolution, for example:
1 out of 100 = 1%
1 out of 1000 = 0.1%
Table 1: Troubleshooting
Precision Meters, Turbine Flow Meters
Page 10 May 2014