Maintenance
20
Hauser
7
Maintenance
7.1
Maintenance tasks
The following tasks are mandatory:
• Cleaning the sensor
• Replace wear parts or consumables:
– Electrolyte
– Membrane body
– Sealing ring
• Check the measuring function:
1. Remove the sensor from the medium.
2. Clean and dry the membrane.
3. After about 10 minutes, measure the oxygen saturation index in air (without recalibration).
4. The measured value should be at 100 ± 2 % SAT
• Recalibration (if desired or required)
7.2
Maintenance intervals
Maintenance cycles depend to a great extent on the operating conditions.
The following rule of thumb applies:
• Constant conditions, e.g. power plant = long cycles (1/2 year)
• Greatly varying conditions, e.g. daily CIP cleaning = short cycles (1 month or shorter)
The following method helps you determine the necessary intervals:
1.
Inspect the sensor one month after commissioning.
Take it out of the medium and dry it.
2.
After 10 minutes, measure the oxygen saturation index in air.
Decide using the results:
a. If the measured value is not at 100 ±2 %SAT, you have to maintain the sensor.
b. Otherwise, double the length of time to the next inspection.
3.
Proceed similarly after two, four and/or eight months. In this way, you can determine the
optimum maintenance interval for your sensor.
Particularly for widely varying process conditions, damage of the membrane can occur even within
a maintenance cycle. You can recognize this by implausible sensor behavior.
