The system comprises of a single unit incorporating an infra-red transmitter and receiver. The signal generated in the transmitter element and reflected by the prism back to the receiver element is analyzed for the presence of smoke. The internal microprocessor determines an alarm condition when a predetermined level is reached.

The system is designed to be mounted so the beam will project between 0.5 m and 0.6 m below and parallel to the ceiling. Lateral detection may be up to 9.144m on either side of the beam, providing a maximum total coverage area of up to 19,800 square feet (18.29 m x 100 m).T