For hold-open systems that are approved according to type approval (AAST type approval Z-6.500-2364), the ORS 142 must be used for both new systems and replacements.|The smoke switch is used to detect smoldering and open fires with smoke development and to control hold-open systems on doors and gates.|The alarm threshold tracking of the ORS 142 ensures a permanent check of the degree of contamination and automatically adjusts the alarm threshold - thus ensuring continuous safe operation.|The smoke switch is used to detect smoldering and open fires with smoke development and to control hold-open systems on doors and gates.