What component of a Safety Instrumented System (SIS) is responsible for making decisions based on sensor input?

The logic solver is the key component of a Safety Instrumented System (SIS) that is responsible for making decisions based on the input received from sensors. In a SIS, sensors detect process variables and send signals to the logic solver, which interprets this data to determine whether safe conditions are being met. If the input indicates that safety thresholds have been exceeded, the logic solver activates appropriate actions to mitigate risks, typically by sending signals to the final elements to execute a safe state, such as shutting down equipment or activating alarms.

This decision-making function is crucial in ensuring that the system can effectively respond to hazardous conditions. The capability of the logic solver to process information and initiate protective actions is what allows the SIS to enhance safety in industrial processes. Other components, like the final element, carry out the physical action generated by the logic solver, while the sensor simply collects data without any processing or decision-making ability. The control room, although important for monitoring and management, does not directly participate in the automatic control or decision-making process of a SIS.