The Siemens DI-A3 Ionization Detector 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.
In Addition, the sensitivity of the Siemens DI-A3 Ionization Detector 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-A3 is was recommend for use in high air velocity applications such as computer room underfloor areas. The model DI-A3 contains a specially designed internal chamber cover and a pre-selected fixed sensitivity setting which provides extremely stable operation. Model DI-A3 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.