ISO 7240-27:2009 specifies requirements, test methods and performance criteria for multi-sensor point-type fire detectors that incorporate an optical or ionization smoke sensor, an electro-chemical cell for sensing carbon monoxide (CO) and, optionally, one or more heat sensors, for use in fire detection and alarm systems installed in buildings (see ISO 7240-1). For the testing of other types of fire detectors using smoke, CO and, optionally, heat sensors working on different principles, ISO 7240-27:2009 can be used only for guidance. Fire detectors using smoke, CO and, optionally, heat sensors which have special characteristics and which have been developed for specific risks are not covered by ISO 7240-27:2009.