Bronkhorst EX-FLOW Mass Flow Instrukcja Użytkownika Pobierz pdf (Strona 23)

BRONKHORST HIGH-TECH B.V.

6 TROUBLESHOOTING

6.1 General

For a correct analysis of the proper operation of a mass flow meter/controller it is recommended to remove

the unit from the process line and to check it without applying gas 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.

Energizing or de-energizing of the instrument may already indicate whether there is an electronic failure.

After that gas pressure is to be applied in order to check flow behaviour.

If there should be suspicion of leakage do not check for bubbles with a leak detection liquid as this may lead

to a short-circuit in the sensor capillary assembly or p.c. board.

6.2 Troubleshooting summary

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 high, or differential

pressure across meter too high

1d) lower supply pressure

Valve blocked/contaminated

1e) return to factory

Screen in inlet fitting blocked

1f) return to factory

Sensor/capillary failure

1g) return to factory

Maximum output signal

Output stage blown-up

2a) return to factory

Sensor/capillary failure

2b) return to factory

Output signal much lower than

setpoint signal or desired flow

Screen blocked/contamined

3a) return to factory

LFD blocked/contaminated and/or liquid

in meter

3b return to factory

Valve blocked/contaminated

3c) return to factory

Valve internals damage (swollen seat in

plunger)

3d) return to factory

Incorrect type of gas is used and/or

pressure/diff. pressure

3e) try instrument on conditions for which

it was designed

Flow is gradually decreasing

Condensation, occurs with

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 MFC

5b) increase length or diameter of piping

upstream

Pressure regulator is oscillating

5c) replace pressure regulator or try ‘5b’

Valve sleeve or internals damaged

5d) return to factory

Controller adjustment wrong

5e) return to factory

Small flow at zero setpoint

Valve leaks due to damaged plunger or

dirt in orifice

6a) return to factory

Pressure too high or much too low

6b) apply correct pressure

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