Ben Hirst Firefighter 2 Practice Test

Heat detectors respond in two main ways: some trigger when the temperature reaches a fixed high value, while others trigger based on how quickly the temperature rises. The description in the question matches rate-of-rise detectors, which activate when the temperature increases by a certain amount over a short period. This means they respond to rapid heating from a developing fire, even if the absolute temperature isn’t extremely high yet.

Fixed-temperature detectors (such as open-chamber and closed-chamber types) go off when the ambient temperature hits a preset threshold, regardless of how fast the temperature is changing. Variable-threshold detectors adjust to ambient conditions to reduce nuisance alarms but still rely on reaching a high temperature, not the rate of change.