FAA Powerplant Written Practice Test

What is the principle of operation of the continuous loop fire detection system sensor?

1. Ore resistance material which prevents current flow at normal temperatures

2. Mechanical switch that activates under pressure

3. Liquid-filled expansion bulb that bursts upon heating

4. Current flow based on light intensity

The correct answer is: Ore resistance material which prevents current flow at normal temperatures

The principle of operation for a continuous loop fire detection system sensor is based on the use of a core resistance material. This material presents a change in resistance when subjected to elevated temperatures, which occurs in the presence of a fire or excessive heat. Under normal conditions, the resistance is high enough to prevent current flow. However, as the temperature rises, typically due to an increase in heat from a fire, the resistance drops, allowing current to flow through the sensor circuit. This change triggers an alarm or warning system indicating the presence of a potential fire hazard. The other options represent different types of fire detection technologies or mechanisms that do not describe how the continuous loop system operates. For instance, mechanical switches and expansion bulbs operate based on movement or physical changes due to temperature but do not continuously monitor temperature in the same way the core resistance material does. Light intensity detection is a separate technology that doesn't apply to the continuous loop concept, which is fundamentally rooted in electrical resistance changes within a circuit.