Which initiating device requires a 'laboratory test' or replacement after a physical test, because it cannot be restored to its original condition?

Question: Which initiating device requires a 'laboratory test' or replacement after a physical test, because it cannot be restored to its original condition?

Answer options:

• Rate-of-Rise heat detector ✅ Fixed-temperature heat detector
• Photoelectric smoke detector
• Duct smoke detector

Correct answer: Fixed-temperature heat detector

Explanation: Fixed temperature heat detectors do not restore after activation; the eutectic alloy or bimetal disc is permanently warped or melted. Rate-of-rise detectors are usually restorable.