BRONKHORST FLEXI-FLOW Compact Instruction Manual page 25

Symptom
Control behavior unstable
No flow (sending a setpoint has no
effect)
Flow rate never reaches setpoint
Pressure signal gradually decreasing
without setpoint change
Measured value or output signal
indicates flow, while there should
be none
9.17.158G
Bronkhorst®
Possible cause
Measurement disturbed by
vibrations
Upstream pressure unstable
Upstream and/or downstream
pressure too high or too low
Wrong process gas selected
Wrong controller settings
Control valve damaged
No fluid supply
Wrong control mode selected
Valve(s) in default state (normally
closed)
Upstream pressure or differential
pressure out of bounds
· Fluid system clogged or blocked
Sensor obstructed or
·
contaminated
Upstream pressure too low
Downstream pressure too high
Differential pressure too low
Process outlet blocked
Process gas condensation
Supplied fluid type does not match
selected fluid type
Process gas condensation
Fluid system leakage
Zero point adjustment performed
incorrectly
Instruction Manual FLEXI-FLOW™ Compact
Corrective action
· If possible, avoid installation in close
proximity of mechanical vibration
Reduce sensitivity to vibrations by using a
·
mass block, shock absorbers, and flexible
tubing
Install pressure regulator or increase buffer
volume between controlling instruments
Adjust pressure and/or set instrument pressure
in accordance with actual process pressure
Select correct process gas
Adjust settings (e.g. with Bronkhorst FlowSuite)
Contact your Bronkhorst representative
Check upstream components for obstruction,
e.g.:
fluid lines
·
· valves
· filters
Check parameter Control mode
·
· Make sure instrument accepts setpoint from
actual setpoint source (bus)
Check if valves are in default state; solve cause if
necessary (see Default valve state
Set upstream pressure to a value within
specifications
Flush the fluid system:
Liquid lines with a non-aggressive cleaning
·
liquid (e.g. ethanol or isopropyl alcohol).
· Gas lines with clean, dry air.
Increase upstream pressure (to a value within
specifications)
Decrease downstream pressure (to a value within
specifications)
Make sure differential pressure is within
specifications
Check process outlet and downstream piping
Decrease upstream pressure or increase gas
temperature
Supply equipment with other fluid or change
fluid type in instrument configuration
Decrease upstream pressure or increase gas
temperature
· Check fluid system for leakage
· Follow mounting instructions when installing
third party components (e.g. adapters, tubing,
valves)
Readjust zero point, following instructions in
Adjusting zero point
22
46
)
24
25