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The word alarm comes from the Old French a l'arme meaning "to the arms", or "to the weapons", telling armed men to pick up their weapons and get ready for action because an enemy may have suddenly appeared. [1] The word alarum is an archaic form of alarm. It was sometimes used as a call to arms in the stage directions of Elizabethan dramas. [2]
A fire alarm notification appliance is an active fire protection component of a fire alarm system. A notification appliance may use audible, visible, or other stimuli to alert the occupants of a fire or other emergency condition requiring action. Audible appliances have been in use longer than any other method of notification.
Fire alarm warning devices can also be set to different volume levels. Notification appliances utilize audible, visible, tactile, textual or even olfactory stimuli [15] [16] to alert the occupants of the need to evacuate or take action in the event of a fire or other emergency. Evacuation signals may consist of simple appliances that transmit ...
Smoke detector mounted on a ceiling. A smoke detector is a device that senses smoke, typically as an indicator of fire.Smoke detectors/alarms are usually housed in plastic enclosures, typically shaped like a disk about 125 millimetres (5 in) in diameter and 25 millimetres (1 in) thick, but shape and size vary.
The technology typically found in motion sensors to trigger an alarm includes infrared, ultrasonic, vibration and contact. Dual technology sensors combine two or more forms of detection in order to reduce false alarms as each method has its advantages and disadvantages. Traditionally motion sensors are an integral part of a home security system.
Stack light in automated production for in-line quality inspection. Stack lights (also known as signal tower lights, indicator lights, andon lights, warning lights, industrial signal lights, or tower lights) are commonly used on equipment in industrial manufacturing and process control environments to provide visual and audible indicators of a machine's status to machine operators, technicians ...
An AWS visual indicator (known as the 'sunflower') An AWS audible indicator (capable of producing two different sounds, clear indication sound = bell, warning indication sound = 'horn'. On modern rolling stock the electromechanical bell and horn is replaced with an electronically generated "chime" or "buzz".
This is an accepted version of this page This is the latest accepted revision, reviewed on 23 January 2025. Type of clock A traditional wind-up (key-wound), mechanical spring-powered alarm clock An alarm clock or alarm is a clock that is designed to alert an individual or group of people at a specified time. The primary function of these clocks is to awaken people from their night's sleep or ...