An ionization detector detects fire in what stage?

An ionization detector is designed to sense the presence of smoke particles in the air, which are typically produced during the very early stages of a fire. This type of detector is particularly sensitive to fast-burning fires that generate small smoke particles, making it effective for detecting fires in the incipient stage. During this stage, a fire is just starting, and the heat and smoke levels are relatively low compared to later stages like smoldering or fully developed fires.

In the incipient stage, the fire is not yet well-established, and the ionization detector can respond quickly to the initial signs of combustion, allowing for a faster alert and potentially mitigating damage or allowing for evacuation. This characteristic makes ionization detectors especially crucial in any safety system, as they provide an early warning that can save lives and property.

In contrast, other stages such as smoldering, flashover, or fully developed fires often involve different detection requirements or types of detectors that can sense broader smoke particles or heat, which are more prevalent in those later stages. Thus, the identification of the incipient stage as the stage where ionization detectors are most effective highlights their primary function in early fire detection.