Texas Fire Alarm License Practice Test

What condition must be met for an Ionization Smoke detector to trip?

1. The conductivity of air decreases

2. The temperature rises above a threshold

3. Pressure drops in the environment

4. Heightened chemical composure in the air

The correct answer is: The conductivity of air decreases

An Ionization Smoke Detector functions based on the principles of ionization, where it uses a small amount of radioactive material to ionize the air within a sensing chamber. When smoke enters this chamber, it disrupts the flow of ions, leading to decreased conductivity of the air. The condition that must be met for the Ionization Smoke Detector to trip is that the presence of smoke diminishes the conductivity of the air in the chamber. When smoke particles enter the chamber, they interfere with the free-flowing ions, which causes the detector to register a change in the current flowing through the circuit. This decrease in conductivity triggers the alarm to alert occupants to potential danger. The other conditions listed, such as rising temperature, pressure drops, or changes in chemical composition, do not directly cause an Ionization Smoke Detector to trip. Instead, those may pertain to different types of detectors or contribute to a broader fire detection strategy but do not specifically relate to the functioning of an Ionization Smoke Detector.