IS-24 Obsolete Product

Ionization Smoke Detector

The IS-24 ionization smoke detector utilizes two bi-colored LED's for status indication purposes. In a normal standby condition the LED's flash green approximately once each second. When the detector senses smoke and goes into alarm the status LED's will latch on red.

A single radioactive source of Americium-241 ionizes two chambers within the detector, a reference chamber and the smoke sensing chamber. The air is ionized by this source and a small DC current flows between the electrodes of each chamber. Smoke can freely enter the sensing chamber, while the inner chamber is virtually sealed to smoke. Smoke entering the sensing chamber causes a reduction in the DC current flow, the voltage imbalance between the two chambers is proportional to the smoke density. When the voltage difference becomes great enough it causes the detector to go into alarm. The two chamber design is utilized to compensate for changes in atmospheric and environmental conditions.

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