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INVUE CR288 CONCENTRATION MONITOR
Installation and Use Manual | Entegris, Inc.
Troubleshooting a TIR curve
Table 1. Troubleshooting a TIR curve
Characteristic of a healthy TIR curve:
If this is not the case:
A smooth active section (highlighted by a box on the
curve) as indicated by a line quality <0.04 and a bright-
ness level near 1.0. The line quality can also be observed
in the zoom display with the brightness value indicated
beneath the TIR curve.
1. Clean the sensor surface
2. Re-zero
3. Initialize the sensor
4. Verify that the sensor is properly shielded from
ambient light
A line quality stating “In Liquid."
1. Press Update several times to verify the problem
is repeatable
2. Ensure there are no air pockets in system flow
A smooth, sharp “shadow curve” or dropoff point.
A typical healthy curve will drop from a brightness of
1.0 at the head to 0.3 at the tail on the y-scale, within a
span of 5 to 10 pixels. A steeper curve indicates improved
measurement resolution.
1. Clean the sensor
2. Re-zero
3. Initialize
4. Optional: Adjust the lower pixel bound used by the
measurement algorithm. The sensor is typically limited
to readings below 1.42.
A curved tail section flattening out at a brightness of
0.3 on the y-scale.
1. Clean the sensor
2. Re-zero
3. Initialize
If the display shows too few tail pixels:
4. Adjust the upper pixel bound used by the measurement
algorithm. The sensor is typically limited to readings above
1.32.
General Troubleshooting
SYMPTOM
PROBABLE CAUSE
REMEDY
Display says “no sensor
present”
Loose cable/bad cable/sensor not
connected
Detach and reattach both ends
Replace or swap cable
Display says “Sensor in Air”
when chemical is flowing
Bubble trapped in flow cell
Turn the sensor upside down (cable
points downward) to release the bubbles.
Mounting in this position may prevent
future occurrences.
Dirt or other optical window fouling
Inspect the TIR on the Diagnostics tab for
a non-linear curve in a “mountain” pattern.
Clean window with a DIW flush and
Re-zero.
Cable issue/sensor malfunction
Inspect the TIR curve on the Diagnostics
tab. If it’s non-linear or not appearing,
swap cables. If there is still a problem,
replace sensor.