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.
West Yorkshire is a metropolitan and ceremonial county in England. It is an inland and, in relative terms, upland county having eastward-draining valleys while taking in the moors of the Pennines. West Yorkshire came into existence as a metropolitan county in 1974 after the passage of the Local Government Act 1972 and has a population of 2.3 million.
West Yorkshire consists of five metropolitan boroughs (City of Bradford, Calderdale, Kirklees, City of Leeds and City of Wakefield) and is bordered by the counties of Derbyshire to the south, Greater Manchester to the south-west, Lancashire to the west and north-west, North Yorkshire to the north and east, and South Yorkshire to the south and south-east.
Remnants of strong coal, wool and iron ore industries remain in the county, having attracted people over the centuries, and this can be seen in the buildings and architecture. Major railways and two major motorways traverse the county, which also contains Leeds Bradford International Airport.
West Yorkshire includes the West Yorkshire Urban Area, which is the biggest and most built-up urban area within the historic county boundaries of Yorkshire.