A door closing coordinator for double-leaf doors ensures the correct closing sequence of the doors — first the passive leaf, then the active leaf. Door closers must be installed on both door leaves.

The closing coordinator works on the principle that if the passive leaf does not close first (which lifts the coordinator), it prevents the active leaf from closing and holds it back. This prevents the doors from closing in the wrong order, which could lead to improper sealing and allow fire or smoke to enter the room.