Bronkhorst®
Instruction Manual EL-FLOW® Prestige
9.17.084N
53
5.3
Common issues
Symptom
Possible cause
Action
No power (LEDs not burning)
No power supply
Check power supply
Check cable connection
Internal fuse blown due to long lasting
shortage
Return to factory
Zero output signal
No setpoint accepted, incorrect control
mode
Check analog/digital control mode (see
section
No setpoint given, setpoint too low
Give setpoint >2%
Valve in 'Safe State' (normally closed
valves)
Remove cause of 'Valve Safe State' (see
section
Pcb/sensor failure
Return to factory
Laminar flow element
blocked/contaminated
Return to factory
Maximum output signal (131.07%)
Flow too high, valve fully open
Close valve
Pcb/sensor failure
Return to factory
Valve in 'Safe State' (normally open
valves)
Remove cause of 'Valve Safe State' (see
section
Setpoint cannot be achieved
Pressure difference across instrument
insufficient to achieve requested flow
rate
Check inlet/outlet pressure
Valve blocked or damaged
Return to factory
Stoppage
Remove contamination
Flow signal is gradually decreasing
without setpoint change
Pressure difference across instrument
insufficient to achieve requested flow
rate
Check inlet/outlet pressure
Process gas condensation occurs
Decrease pressure or increase gas
temperature
Oscillating controller output
Controller adjustment wrong, PID
settings too fast
Decrease
Inlet/outlet pressure too high or too
low
Adjust pressure/set correct instrument
pressure with FlowTune™
Wrong gas selected
Set correct process gas with
FlowTune™
Inlet pressure control is oscillating
Replace pressure regulator or increase
buffer volume between controlling
instruments (see section
'Cross-talk' with other controller
instruments in process line
Increase buffer volume between
controller instruments (see section
Valve is damaged
Return to factory
Non-zero output signal when valve is
closed
Valve is leaking (through valve)
Check valve specifications for leak-
tightness through valve
Non-zero offset signal (occurs at
upward/downward placement at higher
pressures)
See