Aalborg DFM Digital User Manual

Page 52

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NO.

INDICATION

LIKELY REASON

SOLUTION

Gas flows through the
DFM, but LCD Display
reading and The output
voltage 0-5 Vdc signal
do not respond to flow.

The gas flow is too low
for particular model of
DFM.

Check maximum flow range on transducer's
front panel and make required flow
adjustment.

DFM26/27 models:
RFE is not connected
properly to the inlet
fitting.

Unscrew the inlet compression fitting of the
meter and reinstall RFE (see section 6.2.2).
Note: Calibration accuracy can be affected.

DFM36/37/46/47
models: RFE is shifted
and blocked the sensor.

Unscrew the four socket head cap screws at
the inlet side of the meter. Reinstall RFE and
retaining ring (see section 6.2.3).
Note: Calibration accuracy can be affected.

Sensor or PC board is
defective.

Return DFM to factory for repair.

Gas does not flow
through the DFM with
inlet pressure applied
to the inlet fitting. LCD
Display reading and out
put voltage 0-5 Vdc
signal show zero flow.

Filter screen obstructed
at inlet.

Flush clean or disassemble to remove
impediments or replace the filter screen
(see section 6.2).
Note: Calibration accuracy can be affected.

Direction of the gas
flow is reversed.

Check the direction of gas flow as indicated
by the arrow on the front of the meter and
make required reconnection in the
installation.

DFM is connected in
the installation with
back pressure
conditions and gas leak
exist in the system.

Locate and correct gas leak in the system.
If DFM has internal leak return it to factory
for repair.

Gas flows through the
DFM, but LCD Display
reading is negative and
output voltage 0-5 Vdc
signal does not
respond to flow
(reading near 1mV).