Florida Fire State Practice Exam

What type of heat detector utilizes two metals to break a circuit when heated?

1. Bimetallic detector

2. Ionization detector

3. Photoelectric detector

4. Thermal detector

The correct answer is: Bimetallic detector

The bimetallic detector operates based on the principle of thermal expansion of two different metals that are bonded together. When the temperature rises due to a fire, the differing expansion rates of the metals cause them to bend or warp. This movement can break an electrical circuit, triggering an alarm. The sensitivity of this type of detector makes it effective for detecting heat generated by fire. In contrast, the ionization detector functions by using a small amount of radioactive material to ionize the air within a sensing chamber, which is not dependent on temperature changes. The photoelectric detector uses a light source and a light sensor to detect smoke particles, not heat. Lastly, while thermal detectors are designed to respond to heat and can include various mechanisms, they do not specifically utilize the dual metals mechanism that characterizes bimetallic detectors.