Which type of heat detector is not dependent on rates of temperature change?

A fixed-temperature heat detector is designed to activate when a specific temperature is reached, rather than relying on the rate at which temperature changes. This means that it will trigger an alarm once the ambient temperature reaches a predefined threshold, typically designed to be above normal room temperatures and indicative of a fire.

In contrast, rate-of-rise heat detectors are sensitive to the speed at which temperature increases, and they will activate when the temperature rises rapidly. Combined heat detectors utilize both fixed-temperature and rate-of-rise principles, meaning they depend on both temperature thresholds and the rate of change. Rate-compensation detectors are designed with temperature compensation mechanisms that adjust their sensitivity based on the ambient temperature changes.

The fixed-temperature design serves specific scenarios where a set temperature can indicate the presence of heat associated with fire, making it an ideal choice for areas where fast temperature rises may not occur, or where the system needs to provide a simple and reliable response to heat.