FAA Powerplant Written Practice Test

What general type of system utilizes changes in physical properties of materials to relay fire detection?

1. Heat sensitive systems

2. Chemical analysis systems

3. Visual detection systems

4. Circuit-breaking systems

The correct answer is: Heat sensitive systems

Heat sensitive systems utilize changes in physical properties of materials to relay fire detection. These systems often rely on the temperature variations associated with fire, whereby certain materials are designed to react to heat. For instance, they may use thermocouples or bimetallic elements that change their resistance or physical shape at elevated temperatures. When a specific temperature threshold is exceeded, indicating the presence of heat from a fire, the system triggers an alert. Other options, such as chemical analysis systems, involve detecting specific combustion gases or combustion byproducts rather than direct temperature changes. Visual detection systems rely on sight and camera technology to observe and identify fires, while circuit-breaking systems are focused on electrical overloads and do not directly relate to fire detection based on physical properties. This highlights the specificity of heat-sensitive systems in their role for fire detection using the principles of temperature response.