What are the two operating features of heat sensing devices?

Heat sensing devices primarily operate based on two crucial features: rate and rise. The "rate" refers to the speed at which the temperature increases within the environment that the sensing device is monitoring. This aspect is vital because it allows the device to determine whether a temperature increase is happening at a typical, slow pace or at an alarming, rapid pace that could indicate a fire hazard.

The "rise" component pertains to the actual change in temperature that the sensor detects over a given time period. A substantial temperature rise, especially within a short timeframe, can signal an impending danger and trigger alerts or response systems. By analyzing both the rate and rise of temperature, heat sensing devices can provide early warnings of fire, enhancing safety protocols effectively.

In contrast, the other options—temperature and pressure, or rate and interval—do not directly characterize the essential operating features of heat detectors in the context of fire safety. These alternatives involve measurements that, while relevant in other contexts, do not specifically capture how heat sensing devices are designed to monitor and respond to thermal changes.