The DP721I is an optical smoke detector with field exchangeable optical chamber and remote indicator output facilities. It detects the presence of smoke in the environment using the Tyndall Effect, by light scarring measurement in an optical chamber.
700 Series detectors continually monitor their own sensitivity and operational status. Once a day they perform a full diagnostic test that includes dynamically testing the sensing chamber and internal electronics. Any abnormal statuses are reported locally and to the panel.