Failure means which of the following?

• A. The system cannot perform as required
• B. The system is completely broken
• C. The system operates normally
• D. The system is idle

Answer: (A)

Failure means the system cannot perform as required. In instrumentation and maintenance, each function has specified performance criteria. When a component or the whole system cannot meet those criteria—whether due to accuracy, range, response time, or reliability—it is considered to have failed. This doesn't always mean everything is completely unusable; a system can still operate but not meet the required standards, which is still a failure of the intended function.

For example, if a pressure transmitter drifts outside acceptable tolerance and can’t provide an accurate indication, it fails to perform its job even if it’s still sending some signal. That’s why the other descriptions don’t fit: being completely broken is an absolute that isn’t necessary to define failure, operating normally contradicts the failure condition, and being idle means no operation rather than failing to meet required performance.