Which statement best describes a safety critical device?

• A. Where failure could lead to catastrophic consequences
• B. Any device that alarms only
• C. A device used for measurement
• D. An emergency stop only

Answer: (A)

Safety critical devices are defined by what could happen if they fail. If a failure could lead to catastrophic consequences—such as severe injury, loss of life, or major environmental or equipment damage—the device is considered safety critical. That focus on the potential severity of failure is why the best description is the one that centers on outcomes, not just what the device does in isolation.

An alarm-only device may warn of a problem but doesn’t itself prevent harm, so it doesn’t on its own define a safety-critical function. A measurement device provides data without inherently reducing risk. An emergency stop is indeed a safety feature, but labeling it as the only safety-critical device misses the broader idea that many protective systems rely on prevention, detection, and controlled shutdown to avert catastrophe.