Bronkhorst FLOW-SMS Series - Manual (Page 24)

BRONKHORST HIGH-TECH B.V.
9.17.057 page 24
5.3 Troubleshooting summary general
Symptom Possible cause Action
No output signal No power supply Check power supply and hook‐up
Check cable connection and hook‐up.
Check status of LED’s
(see manual 9.17.023 chapter 10)
No setpoint For analog used instruments measure
between pin 3 and 8 of sub‐D9
connector.
For digital use make sure to perform a
read setpoint after sending
Cable damaged or hooked‐up wrong Check and compare signals at both ends
of cable.
PC‐board damaged due to long lasting
shortage and/or high‐voltage peaks Return to factory
No or too low inlet pressure Increase inlet pressure
Open shut‐off at inlet and outlet
Supply pressure too high, or differential
pressure across meter too high Reduce supply pressure
Valve blocked / contaminated Set control mode to valve fully open
and check if it opens
Sensor / capillary failure Return to factory
Maximum output signal Leakage of control valve Set control mode to valve close and
check if it closes
Sensor / capillary failure Return to factory
Output signal much lower than
setpoint signal or desired flow Incorrect type of gas or too low inlet
pressure Test instrument on conditions for which
it was designed
Oscillation Supply pressure / diff. pressure too high Reduce pressure
Pressure regulator of supply pressure is
oscillating or wrong sized Replace pressure regulator
Controller adjustment wrong Adjust controller with PID settings
Flow is gradually decreasing Condensation, can occur e.g. with NH
3
Decrease supply pressure and / or heat
gas to be measured
Small flow at zero setpoint Valve leaks due to damage or dirt Return to factory
Increased zero reading without flow
caused by raised zero‐point Perform an auto‐zero action
No digital communication Occupied or wrong bus address Change address with software or
rotary‐switches
No or wrong bus termination Check cabling and termination