The Edwards photoelectric smoke detector is an interchangeable head and base detector with a light-scattering optical sensor. A pulsed infrared LED light source and a high-speed photodiodesensing element are housed in an omni-directional sensing chamber protected by an insect screen. The chamber is not affected by ambient light. The detector features a field-replaceable optical chamber to simplify cleaning.

The 721UT photoelectric detector includes integral fixed temperature heat detectors. Edwards 700 Series smoke detectors are suitable for use in commercial and industrial environments. If the detector drifts out of its UL Listed sensitivity range or fails internal diagnostics, the alarm LED flashes once a second to indicate trouble. This meets NFPA 72 field sensitivity testing requirements without the need for external meters. Applying a magnet near the detector’s integral reed switch activates a self-diagnostic routine that provides visual indication of sensitivity level, or if service is required. Built-in drift compensation allows the detector to automatically adjust its sensitivity over time as it becomes dirty.