24
USER GUIDE
ENTEGRIS, INC.
INVUE INTEGRATED FLOW CONTROLLERS, MODELS NT6510, NT6520
Diagnostic Guide
Symptom
Possible Causes
Suggestions
1. Flow output
reads 4 mA
when fluid
flow is present.
The unit is installed
backwards.
Install the unit so the inlet flow is
plumbed on the same side as the
electrical connection and flow is in
the direction of the arrow.
Insufficient line pressure/
insufficient pressure drop.
Verify the inlet pressure is adequate
as described in the
Operating Line
Pressure Requirements
on page 21.
Verify the pressure drop meets
the requirements according to the
Operating Pressure Drop Requirements
on page 21.
The unit needs to be
re-zeroed
Perform the re-zeroing procedure.
2. Flow output
reads above 4
mA when there
is zero flow.
The unit needs to be
re-zeroed.
Perform the re-zeroing procedure.
3. Flow output
does not
change with
changing flow.
The pressure output is
being monitored instead
of the flow output.
Check the wiring to ensure the flow
output is wired correctly.
4. Current output
is extremely
high (>25 mA).
The incorrect wires are
connected to the flow
monitoring device.
Confirm wiring. Wire functions are
printed on the unit label.
The 4–20 mA flow signal is
shorted to power (+24 V).
Examine all electrical connections.
Please note, if wires are stripped
back too far before insertion in a
terminal block, they may cross and
short together.
5. Flow output
is extremely
noisy (spiking
above and
below 20 and
4 mA).
The actual fluid flow
conditions are noisy.
Flow turbulence may be caused by
“noisy” pumps used in a system.
Examples of noisy pumps are dia-
phragm pumps with out pulsation
dampeners and peristaltic pumps oper-
ating at low flow rates. Please contact
Entegris for additional information.
The supply power
(+24 V) is noisy.
If the power supply is shared with other
systems, components such as solenoids,
DC motors, valves, etc., the unit may be
receiving “dirty” power. The noise spikes
on the power supply will cause the unit
output to be noisy or cause the unit to
enter a reset mode.
