6 Safety Manual
57
6.10.4 Recommended tests for temperature probes
To ensure safe and reliable operation of the thermometers, the following service and maintenance work must be performed:
The following tests are recommended at certain intervals:
- Every 12 months, the insulation resistance of the measuring circuit must be measured against the protection fitting (for
thermocouples: only for the insulated measuring circuit; in the case of multiple measuring circuits, the insulation test must
also be performed between the individual measuring circuits). The minimal insulation resistance at room temperature
should be 100 MΩ at 100 V.
- Damage and corrosion of thermometers – protection tubes
- Corrosion and correct positioning of the contacts and terminals of cable connections
- Seals of terminal heads and cable bushings
- Interruptions due to "knocking" on the thermometer/measuring insert
Since the maximum operating temperature influences the drift behavior, the thermometer should be recalibrated or replaced at
certain intervals to ensure reliable and precise temperature measurement.
The testing intervals are listed in the table below:
Warning
After the mission time expires, the systems no longer meet the requirements according to their SIL certification.
Maximum operating tempera-
ture
Pt – RTD temperature probe Thermocouples
200 °C 5 years 5 years
550 °C 2 years 5 years
700 °C 1 year 2 years
To Next Page
Loading...
