Endress+Hauser Memosens COS51E, Operating Instructions Manual

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Maintenance Memosens COS51E
30 Hauser
9 Maintenance
Take all the necessary precautions in time to ensure the operational safety and reliability
of the entire measuring system.
NOTICE
Effects on process and process control!
‣
When carrying out any work on the system, bear in mind any potential impact this
could have on the process control system and the process itself.
‣
For your own safety, only use genuine accessories. With genuine parts, the function,
accuracy and reliability are also ensured after maintenance work.
9.1 Maintenance schedule
Maintenance cycles depend to a great extent on the operating conditions.
The following rule of thumb applies:
• Constant conditions, e.g. = long cycles (6 months)
• Widely varying conditions, e.g. fluctuating process pressure = short cycles (1 month or
less)
The following method helps you determine the necessary intervals:
1. Inspect the sensor one month after commissioning. To do so, remove the sensor from
the medium and dry it carefully.
2. To avoid measured errors in the transmitter, change the process pressure to the
atmospheric pressure if not already the same.
 If the process pressure and atmospheric pressure are the same, this step is not
required.
3. After 10 minutes, measure the oxygen saturation index in air.
 Decide using the results:
a) Measured value is not 100 ± 2 % SAT? → Service the sensor.
b) Measured value = 100 ± 2 % SAT? → Double the length of time to the next
inspection.
4. Proceed as indicated in Step 1 after two, four and eight months.
 This allows you to determine the optimum maintenance interval for your sensor.
Especially in the case of widely fluctuating process conditions, damage to the may also
occur within a maintenance cycle. This is indicated by implausible sensor behavior.
9.2 Maintenance tasks
The following tasks must be performed:
1. Clean the sensor and .
2. Replace wear parts or consumables.
3. Check measurement function.
4. Recalibrate (if desired or necessary).
 Follow the Operating Instructions for the transmitter.
9.2.1 Cleaning the exterior of the sensor
Dirt on the sensor can impact the measurement and even cause a malfunction. Examples
include buildup on the sensor membrane, which can cause a longer response time.
The sensor must be cleaned at regular intervals for reliable measurement results. The
frequency and intensity of the cleaning process depend on the medium.