Door closer
Door closers can be linked to a building's fire and security alarm systems.
[5][6] In more modern times the clock manufacturers Thwaites and Reed in 1850 claimed to be the original inventors of the spiral door spring.
[7] The earliest English patent for a door closing device consisting of weights and pulleys was issued in 1786 to Francis Moore.
[8] The first English patent issued that mentions a spring can be traced to a few years later to that of Henry Downer.
[9] (Ironmonger) of Fleet Street, London recognised for the invention of a "spring to shut a door" (1790).
These early "door closers" used a pneumatic piston to check the speed, later models used a hydraulic or oil filled device for the same effect.
[24] Eugene Blount, Francis Richards and Joseph Bardsley also played important parts in the development, improvement and commercialization of door closers along with other companies, including Yale, Norton, Rixson and The Shelby Spring Hinge Company.
These allow setting of the “sweep speed” (the rate which the door travels along the majority of its closure, the sole closing setting on basic closers); the “latch speed” (the rate in the last 10 to 15 degrees of closing arc, allowing it to be set faster than the "sweep" to ensure proper latch closure); “delayed action” (which slows sweep speed dramatically for roughly the first half of its range, allowing more time for passage),[27] and opening speed (preventing a door from being opened too fast, a useful feature in crowded environments, and those where the young, old, or infirm may be present).
[citation needed] The latter include retina scanners, fingerprint readers, and voice recognition technologies.
[28] Electric door closers may also be hooked to a building’s fire alarm system.
A triggered alarm cuts power to any electromagnetic hold-open device, allowing the doors to close.
This type of door closer is referred to as a "tail" spring[31] and is one of the more simple mechanisms, having no damping control.
Storm door closers often have a small metal square washer on the rod that is used to lock the closer in the open position if required, more recent models have a button to actuate the hold open feature to make this process easier.
They are also used in numerous applications in commercial, industrial, institutional, and public facilities from libraries and schools to museums and airports.
Door closers also play a role in maintaining desired interior temperatures, reducing air movement in and out of conditioned space.
Door closers can also play a part in keeping buildings and rooms free from dirt, debris and pests.
