Measurement; Message Outside Light Error; Message No Optical Image; Message Prism Coated - Vaisala K-PATENTS PR-23 Series Instruction Manual

8 Troubleshooting

8.2 Measurement

8.2.1 Message
OUTSIDE LIGHT ERROR
Cause: The measurement is not possible because too much outside light reaches the
camera.
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.
8.2.2 Message
NO OPTICAL IMAGE
The optical image can be seen from selecting
tion 5.4.1. There are several possible causes:
1. The prism is heavily coated, Section 4.1. Perform prism wash if available, Sec-
tion 5.1.3 "Testing prism wash". Remove sensor from line and clean prism manu-
ally.
2. There is moisture condensation in the sensor head, see Section 8.1.7.
3. The sensor head temperature is too high, see Section 8.1.8.
4. The light source is faulty. When the sensor is removed from the process, the yellow
flashing light can be seen through the prism. Note: The light is only visible at
an oblique angle. Also check the LED value in the Sensor status display (select
in the Main menu); if the value is clearly below 100, LED fault is not
SENSOR STATUS
likely.
5. There are negative spikes in the optical image. The probable cause is dust or fin-
gerprints on the CCD window.
6. The CCD card in the sensor is faulty.
8.2.3 Message
PRISM COATED
Cause: The optical surface of the prism is coated by the process medium or impurities
in the process medium.
Action: Perform prism wash if available, Section 5.1.3 "Testing prism wash". Remove
sensor from line and clean prism manually.
If the problem is recurrent, consider improving the flow conditions (see Section 2.2,
"Mounting the sensor") or, if prism wash is available, adjust the wash parameters, see
Section 6.5, "Configuring prism wash".
at the Main menu, Sec-
3 SENSOR STATUS
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