This European Standard specifies requirements, test methods and performance criteria for fire detectors which detect smoke in air ducts in buildings as a part of a fire detection and fire alarm system or as an actuator for a fire protection system. Duct smoke detectors with special characteristics and developed for specific risks are not covered by this document. NOTE Certain types of detector contain radioactive materials. The national requirements for radiation protection differ from one member state to another and are not specified in this standard.