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The door holders release, allowing the doors to close automatically using door closers. [1] [2] The electric power to keep the doors open is typically 12 VDC, 24 VDC (common), 24 VAC, 120 VAC, or 240 VAC. The closed doors may or may not mechanically latch or lock in the closed position.
Some fire doors are held open by an electromagnet, which is typically wired to a fire alarm system. If the power fails or the fire alarm is activated, the coil is de-energized, and the door closes. Wireless, battery-operated, fire door retainers can also be used to safely and legally hold fire doors open. Rated fire doors are tested to ...
Fail-safe locking devices are unlocked when de-energized. Direct pull electromagnetic locks are inherently fail-safe. Typically the electromagnet portion of the lock is attached to the door frame and a mating armature plate is attached to the door. The two components are in contact when the door is closed.
A door closer is a mechanical device that regulates the speed and action of a door’s swing. [1] Manual closers store the force used to open the door in some type of spring and reuse it to close the door. Automatic types use electricity to regulate door swing behavior. Door closers can be linked to a building's fire and security alarm systems. [2]
The automatic door used a mat actuator. In 1960, they co-founded Horton Automatics Inc and placed the first commercial automatic sliding door on the market. [5] With the invention of the Gunn diode, microwave motion detectors became common in automatic doors in the 1970s. [6] [7] In 1980, the first automatic door using an infrared sensor was ...
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