SIS issues in batch reactors
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A BOOL variable is set on the DCS side, with two states: oven operation and normal reaction. These two states have different SIS temperature values, and logical interlocks are implemented by using the status value from the DCS. As for the 2 states on the DCS side, they can be switched manually by the operator or determined through DCS logic. It is not recommended to disable the SIS interlocks in order to dry the equipment; with the SIS interlocks still in place, the interlock value for the drying temperature will simply be a bit higher.
Regarding the SIS (Safety Instrumented System) issues for batch reactors, it is recommended to establish a boolean variable in the DCS (Distributed Control System) that has two states: dryer mode and normal reaction mode. The SIS temperature values are different in these two states. Logical interlocking can be achieved by reading the status values in the DCS. The two states at the DCS side can be switched manually by the operator, or determined automatically by DCS logic. It is not recommended to dry the equipment by removing the SIS interlock; instead, this should be achieved by setting different states. In the oven mode, the SIS temperature interlock value is slightly higher, but the interlock function remains intact to ensure the safe operation of the equipment. .
Can it be determined that SIS can use the status variables of DCS for logical interlocking?