In general, modern measuring devices that already have a factory-set fault detection level and thus low failure rates are suitable for this purpose: The necessary PFD calculation (PFD: Probability of Failure in Demand) already results in an arithmetical proof with a long test interval. In addition, automated partial proof tests can help to extend the test intervals.
Another good possibility for optimization is to use the components of the control equipment that needs to be monitored: If, for example, the measured value of a level measurement is duplicated and fed into the safety system, a diagnostic coverage (DC) of 90% to the sensors of the safety equipment can be realized. A redundant shutdown of the control valve parallel to the valve flap also significantly increases the safety level of the system.
But the use of modern verification devices can also be very helpful for both the operation and maintenance of safety loop: With myDevice, KROHNE has developed a portfolio of test and verification equipment that can be used to achieve very high device test depths. In addition, it is possible to verify measuring devices wirelessly via a secure Bluetooth connection even during measurement operation.
