A door closer is a mechanical device that is used on commercial property doors. A manual door closer stores the energy used in the opening of the door and releases it to close the door. To limit the speed at which the door closes, common door closers use hydraulic (oil-filled) dampers, although spring mechanisms may also be used. The speed at which the door closer closes the door may be adjustable by up to two set screws. These screws often adjust the sweep speed and the latch speed of the door.
There are three styles of door-closer: overhead, surface-mounted and jamb-mounted. There are two ways that the door closers can be powered – manual and automatic.
Manual door closers come in two main forms, overhead and jamb mounted. Overhead door closers can be concealed or surface mounted, whereas jamb mounted closers fit between the door and the door frame and are totally concealed when the door is closed.