ROEYKVARSLER

A smoke detector containing at least one smoke measuring chamber which possesses a mounting or socket plate having an upper surface intended to be mounted at the ceiling of a room or other appropriate area to be monitored and a housing enclosing the smoke measuring chamber and suspendingly secured at the socket plate. The housing possesses openings for the entry of the ambient air into the smoke measuring chamber. The smoke detector comprises a manually adjustable device by means of which it is possible to change the air entry opening in a manner such that the smoke detector can be accommodated to different environmental or ambient conditions, especially those containing different quantities of dust and other contaminants. A hood ring member, movably supported at the inside of a sleeve member of the smoke detector, can be selectively displaced in order to change the air entry openings.