INVUE ELECTRONIC FLOWMETER, MODEL NT4400
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User Guide | Entegris, Inc.
Diagnostics
Troubleshooting the InVue Electronic
Flowmeter, NT4400 may be accom-
plished by measuring the current
(4 – 20 mA) output signal of the flow-
meter with a battery powered current/
voltage meter. The meter may be
placed in series with a flowmeter
output to measure the current output
or it may be used to directly measure
the voltage from a load resistor.
Using the battery powered current/
voltmeter is an effective method
to determine whether the Entegris
device or the on-site data acquisition
system is not functioning properly.
Diagnostics Guide
SYMPTOM
POSSIBLE CAUSES
SUGGESTIONS
1. Current output
reads 4 mA or
less when fluid
flow is present.
The flowmeter is
installed backwards.
Install the flowmeter so the direction of
flow is from inlet towards outlet (direction
of the arrow).
The flowmeter was
accidentally re-zeroed
while flow was present.
Make sure the flow is stopped, and that
there is a minimum of 7 kPa (1.0 psig)
static line pressure present, then re-zero
the flowmeter. See page 17. Use the
included pressure output to verify the
re-zero pressure.
Insufficient line
pressure.
The line pressure (i.e., back-pressure must
be 7 kPa (1.0 psig). If the back- pressure is
being supplied by a column of liquid, the
column height must be greater than
28 inches of water (7 kPa [1.0 psig]). Some
liquids may require greater height due to
lower density. Use the included pressure
output to verify the re-zero pressure.
The actual flow
is lower than the
specified flow range
for the flowmeter.
A flowmeter configured to a different
flow range is required. For example, if
the flowmeter is a T7 unit, any flow less
than 1.0 L/min will read 4 mA. Please
contact Entegris for additional product
information.
Improper wiring.
Verify main power connection
(Red and Black wires).