What type of fire detection system operates on the principle of rate-of-temperature rise?

The correct answer is the thermocouple system, which operates based on the principle of rate-of-temperature rise. This type of detection system functions by measuring the temperature increase over time within a defined area, such as a powerplant. When a fire occurs, the temperature in the vicinity of the thermocouple increases rapidly, and the system is designed to detect this change in temperature. The thermocouple generates an electrical signal proportional to the temperature change, which is then analyzed to determine whether a fire is present.

This system is particularly effective in environments where rapid temperature changes are indicative of fire conditions. By monitoring the rate at which temperature rises, it can provide early warning of combustion, allowing for timely responses to potential fire hazards before they escalate.

Other systems mentioned, such as optical sensor systems, ionic sensor systems, and heat-sensitive tape, operate on different principles. Optical sensors generally detect smoke and particulate matter in the air, while ionic sensors rely on changes in ionization levels caused by smoke or flame. Heat-sensitive tape functions based on fixed temperature thresholds rather than the rate of temperature change, and thus, it is not capable of providing the same level of early detection as a thermocouple-based system.