A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium, and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada and can be either continuous or set to different codes. Fire alarm warning devices can also be set to different volume levels.
The Metropolitan Borough of Bolton /ˈboʊltən/ (About this soundlisten) is a metropolitan borough of Greater Manchester, England, named after its largest town, Bolton, but covering a far larger area which includes Blackrod, Farnworth, Horwich, Kearsley, Westhoughton, and part of the West Pennine Moors. It has a population of 276,800.
The boundaries were set by the Local Government Act 1972, and cover eight former local government districts; seven Urban Districts from the administrative county of Lancashire, and the County Borough of Bolton. The metropolitan districts of Bury, Salford and Wigan lie to the east, south and west respectively; and the unitary authority of Blackburn with Darwen and the non-metropolitan district of Chorley in Lancashire to the north and north-west.