The Siemens DI-3 Conventional Device is a plug-in, ionization detector and is design for two-wire system operation. The DI-3 is design with adjustable sensitivity while the DI-A3 and the DI-B3 have a fix sensitivity design for their individual high airflow applications. The DI-3, DI-A3, and DI-B3 consist of self-compensating dual ionization chambers and a highly stable solid-state amplifier-switching circuit. One chamber detects the presence of combustion products, the second chamber serves as a reference, to stabilize the detector’s sensitivity for changes in environmental conditions. Also, as products of combustion enter the sampling chamber, the chamber current is reduce to produce a voltage change. At the time the voltage range exceeds the pre-determined threshold, an alarm is produce in the control unit. The detector locks in upon alarm and will reset from the control panel.
In Addition, the sensitivity of the Siemens DI-3 Conventional Device is preset at the factory. The electrical sensitivity can be monitor in the field using the Cerberus Pyrotronics sensitivity tester, test module TM-I3.
DI-3 is was recommend for use in high air velocity applications such as computer room underfloor areas. The model DI-3 contains a specially designed internal chamber cover and a pre-selected fixed sensitivity setting which provides extremely stable operation. Model DI-3 is been UL list for operation in air velocities of 0 to 1200 feet per minute. Since air velocity has an effect on detector sensitivity and performance, the DI-A3 should will be use only in applications that meet this established air velocity range.
The detector shall be specifically design for use in high air velocity applications of between 0 and 1200 ft./min.