A bank has 2 or more doors in one opening. If there are only 2 doors, there must be a mullion between them when the doors are swinging in the same direction but from opposite jambs (see example 1). If there are only 2 doors, a mullion is not required between them if the doors are swinging in the same direction and are of the same handing (see example 2). If there are 3 or more doors, the opening is a bank whether or not a door mullion is present between the doors (see example 3 below). It is possible to have a pair of doors within a bank of doors in one opening.
A pair has 2 doors in a 3-sided frame with no mullion between the doors. To be a pair, the doors must swing in the same direction but from opposite jambs. Exception: A pair could have a mullion but only if that mullion is located behind the doors (for the application of two rim exit devices).
A double egress opening is considered a bank of doors in the LaForce system, even though it uses a 3-sided frame, has 2 doors and there is no mullion between the doors. Double egress are considered banks because the doors swing in opposite directions and they need to be beveled and undersized, more similar to doors which are part of a bank, not a pair.
** Typically the active leaf is on the right; therefore, B1 or P1 is the furthest leaf to the right.
See also our Door, Frame, and Hardware Glossary for any unfamiliar terminology!