A (n) detector is one which responds to rapid changes in temperature.

• A. Photoelectric
• B. Ionization
• C. Rate-of-rise
• D. Fixed-temperature

Answer: (A)

Rate-of-rise heat detectors respond to rapid changes in temperature by monitoring how quickly the air temperature increases. They trip when the temperature rises at a rate that exceeds a preset threshold, such as a certain degrees per minute, even if the ambient temperature isn’t high yet. This makes them effective for fast-flaming fires that cause a quick heat spike. By contrast, fixed-temperature detectors activate only when the ambient temperature reaches a specific value, which can delay detection. Photoelectric detectors detect smoke by light scattering, and ionization detectors respond to changes in ionized air caused by flames, not temperature change. So, the detector described is the rate-of-rise type.