ATI Q46D Dissolved Oxygen System Part 10 - Troubleshooting
56
O&M Manual
Rev-N (4/21)
Failure of oxygen calibration. FAIL icon will
not extinguish until successful calibration
has been performed, or 30 minutes passes
with no keys being pressed.
Clean sensor redo zero and span calibration.
If still failure, sensor slope may be less than
20% or greater than 500%. Perform sensor
tests as described in section 10.4. Replace
sensor if still failure.
Failure of temperature calibration. FAIL icon
will not extinguish until successful
calibration has been performed, or 30
minutes passes with no keys being
pressed.
Clean sensor, check cal solution temperature
and repeat sensor temp calibration. TC
calibration function only allows adjustments
of +/- 6 ºC. If still failure, perform sensor
tests as described in section 10.4. Replace
sensor if still failure. .
Internal nonvolatile memory failure
System failure, consult factory.
Internal software storage error.
System failure, consult factory.
Internal display driver fail.
System failure, consult factory.
Failure of factory temperature calibration.
10.4 Sensor Tests
1. Check the membrane condition. A membrane that is not stretched smoothly
across the tip of the sensor will cause unstable measurements. If necessary,
change membrane and electrolyte.
2. Dissolved oxygen sensors can be tested with a digital voltmeter (DVM) to
determine if a major sensor problem exists. Follow the steps below to verify
sensor integrity:
A. Prior to disconnecting the sensor, measure the sensor output voltage
at the analyzer terminal strip with a DVM while the sensor is hanging
in air. If the sensor has been connected to a powered analyzer for at
least 12 hours, the nominal output of the sensor will be about
+400mVDC when measured in air at 25C (100% saturation) from
BLACK (-) to RED (+) on the analyzer terminal strips. This value is
affected by temperature, pressure, and age of the sensor so it’s
possible to see a typical value that ranges from perhaps +200mVDC
to about +800 mVDC under a wide range of conditions in air.
A. Disconnect the five sensor wires from the oxygen monitor. Those
wires are color coded red, white, blue, green, brown, and black.
Note that the brown wire may be replaced with a orange wire in
some cables.
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