Patent ID: 8791826

Claim:
A method for detecting fires in enclosed environments ( 1 ) which are subject to regulations on prevention of explosions, out of which an air-dust mixture is filtered while the dust concentration in the air-dust mixture is reduced below the explosion threshold by means of filters ( 2 ) and the aspirated air-dust mixture checked for burning characteristics and, if necessary, a fire alarm activated, wherein: the functioning of the filter ( 2 ) is monitored, fire detection takes place outside ex-zones, using an aspirating smoke detector system ( 7 ) without an approval for use in areas where there is risk of explosion ex-zones, and if the filter ( 2 ) is determined faulty, a signal processing unit ( 15 , 15 . 1 ) of a malfunction monitoring sensor ( 14 ) generates a signal which triggers a subsequent action that prevents ingress of an aspirated air-dust mixture with an elevated dust concentration into the aspirating smoke detector system ( 7 ).