In the case of doors with two opening leaves that close automatically (e.g. by means of a door closer, a hold-open system or a door drive), it must be ensured that both leaves close in the correct order, i.e. that the movement leaf only closes after the stationary leaf. Otherwise, the rebates of both door leaves can tilt and close the element incompletely, this can pose a safety problem with fire protection doors (fire protection or smoke protection doors), but also with external doors, for example.
Correct closing is ensured by a so-called closing sequence laying, which automatically closes the aisle leaf only when the stationary leaf of the door is already closed. The locking sequence is a component of the door closer, the hold-open system or the door drive. Depending on the system, there are mechanical closing sequence controls (according to DIN EN 1158) and electrical closing sequence controls.
Source: bauwion
