The JA-82ST consists of two independent detectors – an optical smoke detector and a heat detector. The optical smoke detector works on the principle of scattered light and is very sensitive to large dust particles which are present in dense smoke. It is less sensitive to smaller particles generated by the combustion of liquids such as alcohol. That is why there is also a built-in heat detector which has a slower reaction but is much better at detecting fire which generates heat quickly with a small amount of smoke. The microprocessor performs digital analysis of these values which markedly increases false alarm immunity.