Which type of detector is best suited to sense invisible particles from a flaming fire?

The ionization detector is the most suitable choice for sensing invisible particles from a flaming fire. This device contains a small amount of radioactive material that ionizes the air within the sensing chamber. When smoke particles from a fire enter this chamber, they disrupt the ionization process, which decreases the electric current flowing through the detector. This results in an alarm being triggered.

Ionization detectors are particularly effective for detecting fast-burning fires, such as those that produce small, invisible combustion particles—common in flaming fires. Their design allows them to respond quickly to these types of smoke, making them ideal for scenarios where rapid detection is critical.

In contrast, photoelectric detectors are better at sensing larger smoke particles, typically associated with smoldering fires, which may not trigger as quickly during flaming fires. Heat detectors respond to the temperature increase rather than smoke presence, and combination detectors can handle various situations but might not be as quick in responding specifically to flaming fire particles as ionization detectors.