All shutoff systems shall be which of the following?

• A. Be fail-safe
• B. Require manual resetting
• C. Function with the system operation
• D. All of the above

Answer: (D)

Shutoff systems are designed to move the process to a safe state any time something goes wrong. Being fail-safe means that if a fault or power/control loss occurs, the system will default to shutting down the hazard rather than continuing to operate. Requiring manual resetting ensures that after a fault, an authorized person must verify conditions are safe and intentionally restart the system, preventing automatic or hidden resumption of operation. And they must function with the system operation, meaning the shutoff responds in harmony with the system’s controls and interlocks so the shutdown actually stops the hazard when needed. Because all of these behaviors work together to keep people and property safe, the best choice is that all of these characteristics apply.