Door closer in Friern Barnet. This door closer was installed on the entrance in a small block of flats where there were a set of heavy wooden double doors. Door closers are used in cases where there is an entrance which is used several times a day by many occupants and it is essential that the door automatically closes and locks every time it is used. An automatic door closer does exactly that. After being opened the spring arm which is placed at the top of the door pulls the door shut at a slow speed so that it does not slam but firmly enough so that the lock engages. The speed of the closer is adjusted to suit the weight of the door.