A device that responds when the temperature rises at a rate exceeding a predetermined value is a which detector?

A device that responds when the temperature rises at a rate exceeding a predetermined value is a which detector?

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

Answer: (B)

Rate-of-rise heat detectors monitor how fast the air heats up, not just how hot it gets. They are set to trigger when the temperature increases at a rate exceeding a predetermined value, so a rapid heat surge from a flamespread is detected quickly even if the absolute temperature hasn’t reached a high threshold yet. This makes them effective for quickly sensing fires in spaces where a steady rise might be misleading or delayed to a fixed threshold. In contrast, a fixed-temperature detector waits for the ambient temperature to reach a specific level, regardless of how quickly the temperature rises. Smoke detectors like photoelectric and ionization detectors respond to smoke particles, not rapid heat changes, so they’re not the type described here.

Rate-of-rise heat detectors monitor how fast the air heats up, not just how hot it gets. They are set to trigger when the temperature increases at a rate exceeding a predetermined value, so a rapid heat surge from a flamespread is detected quickly even if the absolute temperature hasn’t reached a high threshold yet. This makes them effective for quickly sensing fires in spaces where a steady rise might be misleading or delayed to a fixed threshold. In contrast, a fixed-temperature detector waits for the ambient temperature to reach a specific level, regardless of how quickly the temperature rises. Smoke detectors like photoelectric and ionization detectors respond to smoke particles, not rapid heat changes, so they’re not the type described here.