Bronkhorst Mass Flow - Manual (Page 27)

BRONKHORST HIGH-TECH B.V.
5 Troubleshooting
5.1 General
For a correct analysis of the proper operation of a flow/pressure 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 cover and check if all connectors are fixed properly. Energizing or de-energizing of
the instrument of the instrument indicates whether there is an electronic failure.
After that, fluid pressure is to be applied in order to check behaviour.
If there should be suspicion of leakage in case of a gas unit, do not check for bubbles with a leak detection
liquid under the cover as this may lead to a short-circuit in the sensor or p.c.board.
5.2 Troubleshooting summary
Symptom Possible cause Action
No output signal No power supply 1a) Check power supply
1b) Check cable
PCB failure 1c) Return to factory
Valve blocked 1d) Clean valve (qualified
personnel only)
Filter or screen blocked 1e) Clean filter or screen
Sensor failure 1f) Return to factory
Maximum output signal PCB failure 2a) Return to factory
Sensor failure 2b) Return to factory
High setpoint vs. output offset PCB failure 3a) Return to factory
Valve blocked 3b) Clean valve (qualified personnel only)
Stoppage 3c) Remove cause
Pressure not correct 3d) Check pressure
Signal lower than expected System stoppage 4a) Remove cause
Flow is gradually decreasing (Gas) Condensation 5a) Decrease supply pressure or increase
temperature
Valve adjustment has changed 5b) Check valve adjustment
Oscillation Controller adjustment wrong 6a) Check controller setting
Input pressure wrong 6b) Adjust pressure
Valve damaged 6c) Check valve
Volume / tubing between controller and
pressure controller too small/ short 6d) Improve situation
Small flow occurs when valve is supposed
to be closed Valve is leaking 7a) Check valve
9.17.001 page 27