Bronkhorst CORI-FLOW - Manual (Page 26)

BRONKHORST CORI-TECH B.V.
7 TROUBLESHOOTING
7.1 General
For a correct analysis of the proper operation of a CORI-FLOW meter or controller it is recommended to
remove the unit from the process line and check it without applying fluid supply pressure. In case the unit is
dirty, this can be ascertained immediately by loosening the compression type couplings and, if applicable the
flange on the inlet side.
Furthermore remove the two covers and check if all connectors are fixed properly. Energising or de-
energising of the instrument indicates whether there is an electronic failure. When powering up the red LED
is on and the green LED is flashing for a second or two. Then the instrument should go in normal operation
mode. See document number 9.17.023 for detailed description of the LED indication.
After that, fluid pressure is to be applied in order to check behaviour.
7.2 Troubleshooting summary general
Symptom Possible cause Action
No output signal No power supply 1a) check power supply
1b) check cable connection
Output stage blown-up due to long lasting
shortage and/or high-voltage peaks
1c) return to factory
Supply pressure too low, or differential pressure
across meter too low
1d) increase supply pressure
Valve blocked/contaminated 1e) connect 0 .. 15 Vdc to valve and slowly
increase voltage while supply pressure is ‘on’.
The valve should open at 7V ± 3V; if not open,
then clean parts and adjust valve (qualified
personnel only)
Screen in inlet fitting blocked 1f) clean screen
Sensor failure 1g) return to factory
Maximum output signal Output stage blown-up 2a) return to factory
Sensor failure 2b) return to factory
Output signal much lower than
setpoint signal or desired flow
Screen blocked/contamined 3a) clean screen
sensor blocked/contaminated 3b) clean sensor with a gas or fluid
Valve blocked/contaminated 3c) clean valve
Valve internal damage (swollen seat in plunger) 3d) replace plunger assembly and adjust valve
or return
Incorrect type of gas is used and/or pressure/diff.
pressure is to low
3e) try instrument on conditions for which it was
designed
Flow is gradually decreasing
Condensation, occurs with NH
3 , hydrocarbons
such as C H ,C H
3 8 4 10 etc.
4a) decrease supply pressure and/or heat gas
to be measured
Valve adjustment has changed 4b) see ‘1e’
Oscillation Supply pressure/diff. pressure too high 5a) lower pressure
Pipeline too short between pressure regulator
and Cori-Flow
5b) increase length or diameter of piping
upstream
External vibration is present 5c) Remove external vibration
Valve sleeve or internals damaged 5d) replace damaged parts and adjust valve,
see ‘1e’ or return to factory
Controller adjustment wrong 5e) adjust controller
Software like FLOWPLOT can be used to do
this. Please contact the distributor for details.
Small flow at zero setpoint Valve leaks due to damaged plunger or dirt in
orifice
6a) clean orifice and/or, when replacing plunger
assembly, see ‘1e’
Pressure too high or much too low 6b) apply correct pressure
Zero procedure not done 6c) Zero the instrument
High flow at zero setpoint Damaged diaphragm (only applicable to valves
with membrane)
7a) replace membrane seal
Zero procedure not done 7b) Zero the instrument
Disturbances in the flow Gas in the system 8a) Purge the system
Expansion of liquids to gasses 8b) Check properties fluid used
Calibration error Zero procedure not done 9a) Zero the instrument
Gas in the system 9b) Purge the system
Measure time to short 9c) Measure long enough to get a reliable
measurement
Right reference instrument 9d) The Cori-Flow is a mass-flow
meter/controller and should not be checked with
a volume-meter.
Note: For other (more specific) problems see also troubleshooting parts in other documents.
page 26 9.17.031