Rate-of-rise detectors trigger based on what?

• A. Rate of rise in temperature
• B. Absolute temperature
• C. Smoke concentration
• D. Humidity

Answer: (A)

Rate-of-rise detectors respond to how fast the temperature increases, not just how hot it is at a given moment. They are set to trip when the temperature climbs above a preset rate (for example, a rapid rise of several degrees per minute). This lets them detect quickly developing fires earlier than fixed-temperature devices, since the heat can surge rapidly before reaching a high absolute temperature. They don’t rely on smoke presence or humidity readings, which is why those options don’t fit. In short, the detector watches dT/dt—the rate of heat increase—rather than the current temperature.