Vaisala K-PATENTS PR-23 AX Series, Instruction Manual

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72 PR-23 instruction manual
8.2.4 Message
OUTSIDE LIGHT TO PRISM
Cause: Some light from the outside reaches the sensor and may disturb the measure-
ment.
Action: Identify the light source (for example sun shining into an open tank or a
translucent pipe) and block the light from getting to the prism at the sensor tip.
8.2.5 Message
LOW IMAGE QUALITY
Cause: The most likely cause for this message is scaling on the prism. There still is a
optical image available, but the measurement quality may not be optimal.
Action: Clean the prism, see Section 8.2.3 above.
8.2.6 Message
NO SAMPLE
The operation of the equipment is OK but there is no process liquid on the prism. The
optical image looks like the left image in Figure 5.8 or Figure 5.6.
8.2.7 Message
TEMP MEASUREMENT FAULT
Indicates faulty temperature element. Replace the temperature element.
Note: A difference to some other process temperature measurement is not a fault.
PR-23 measures the true temperature of the prism surface.
8.2.8 Concentration drift during
NORMAL OPERATION
For drift upward, suspect prism coating, Section 4.1, “Prism coating”. Otherwise check
calibration (Section 6.4, “Calibrating the concentration measurement”) and sensor
verification (Chapter 13, “Sensor verification”).