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4.1 Division of alarm areas 4.1.1 Alarm areas shall be divided according to fire compartments or floors. An alarm area should consist of one or several adjacent fire compartments on the same floor. 4.2 Division of detection areas 4.2.1 The division of detection areas shall comply with the following provisions: 4.2.1.1 Detection areas shall be divided according to individual rooms (units). The area of a detection zone should not exceed 500 m2 ； A room whose interior can be seen from the main entrance and whose area does not exceed 1000 m2 can also be designated as a detection area. 4.2.1.2 The detection range length of infrared beam linear smoke fire detectors should not exceed 100 m ； The detection range of a cable-type temperature-sensitive fire detector should not exceed 200 meters ； The detection range length of an air duct differential temperature fire detector should be between 20 and 100 meters. 4.2.2 For secondary protection targets that meet one of the following conditions, several rooms can be designated as one detection area. 4.2.2.1 There shall be no more than 5 adjacent rooms, with a total area not exceeding 400 m2, and a lighting display device shall be installed at the door. 4.2.2.2 There shall be no more than 10 adjacent rooms, with a total area of no more than 100 m2; the interior of each room shall be clearly visible from its door, and a lighting display device shall be installed at the door. 4.2.3 The following areas shall be designated as separate detection zones: 4.2.3.1 Open or enclosed stairwells ； 4.2.3.2 Antechambers of smoke-proof stairwells, antechambers of fire elevators, and antechambers shared by fire elevators and smoke-proof stairwells ； 4.2.3.3 Corridors, ramps, pipe shafts, cable tunnels ； 4.2.3.4 Attics and mezzanines of buildings.