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4-20 mA output will be set either below 4 mA or above 20 mA depending on the type of problem
found.
The following tables provide easy-to-follow instructions to troubleshoot flow indication problems
and interpret instrument fault codes.
TABLE I. Troubleshooting Guide - Flow Indication Problems
OBSERVATION
PROBABLE CAUSE
REMEDY
Flow indication continually
drifting downward with constant
flow.
1.
Coating forming on wetted
surface of sensor.
1.
Clean sensor periodically.
Flow indication saturates high or
low — will not respond to flow
change.
1.
Flow rate not within range
of meter.
2.
Calibration out of range of
actual flow.
3.
Partially failed component
in sensor or transmitter.
4. Setpoint set to High or Low
Flow
1.
Check flow range requirements.
2.
Return to factory for recalibration.
3.
Consult factory.
4.
Adjust setpoint away from High or Low range
Flow indication varies with flow
setpoint but is not stable.
1.
Fluid temperature not
stable.
2.
Fluid mixture not properly
blended.
3.
Gas mixed with liquid.
4.
Flow not fully developed.
1.
Tune temperature controller, add insulation and/or
add static mixer in front of sensor. Monitor
temperature indication. Refer to Installation
Section for discussion on thermal stabilizing flow
system.
2.
Add static mixer in front of sensor.
3.
Reduce gas pressure or check for air ingress on
suction side of pump. Refer to Installation Section.
4.
Check inlet for proper straight line length & freedom
from obstructions.
Display frozen, showing NaN,
display scrambled, or black
1. Unable to communicate with
flow sensor
1. Cycle power to instrument.
2. Contact factory for further assistance.
Flow never reaches setpoint.
1. Not enough pressure in flow
system.
1. Increase motive force, i.e. centrifugal pump speed or
air pressure.
Slow response on startup
1. Setpoint is set close to low
end of range
1. Increase setpoint temporarily or wait for flow to
stabilize.
