providing soft closing. Mechanical closers, on the other hand, also provide closing force and speed control but by using object friction rather than oil. The absence of an oil damper makes mechanical closers more resistant to drastic temperature changes. Usage Fire safety Door closers are most commonly installed on bathroom doors, fire doors, and exit doors in commercial buildings. During a fire, any door that penetrates a firewall must be fire-rated. Fire doors need to be closed in case of fire to help prevent the spread of fire and smoke. Any fire doors which are normally held open must automatically close and lock when a fire is present in the building. The function of an emergency exit rim device (crash bar or panic bar) will permit escape through a fire door, however it must re-latch once released. (A fire door must not be "dogged" to disable its latch.) In most countries fire door performance will be governed by national standards. Maintaining room temperatures Door closers also play a role in maintaining desired interior temperatures, reducing air movement in and out of conditioned space. Security Door closers also play a role in security at building entrance doors, closing doors once somebody has passed through and re-latching the door lock. Noise control In buildings that require noise control (Studios) door closers play an important part in the suppression of unwanted noise both in and out rooms and the buildings themselves. Privacy Door closers are often used to ensure privacy in toilets and washrooms. Hygiene Door closers can also play a part in keeping buildings and rooms free from dirt, debris and pests. See also Door loop, a method for providing electric cabling to a door References External links Door automation Ironmongery Door furniture