Exit devices are designed to be installed onto the secure side of outswinging doors. They restrict access while providing free egress. The exit device developed in the United States was introduced after the loss of lives in a number of building fires, including the infamous Iroquois Theatre Fire of 1903, where more than 600 people died. The exit device solved the problem of people being crushed against the doors because they first did not have prior knowledge of how to open the door or time to unlock and open the door.
Early exit devices used a metal tube (cross bar) between two cases that were attached onto each side of the door. The active case has a latch bolt that would retract when the tube was pushed in a downward and forward direction, permitting the door to swing open. This way, if someone “crashed” into the exit device, the latch would release and the door would swing open.
A number of manufacturers continue to offer the traditional cross bar. Precision Hardware’s Olympian Series crossbar style exit devices chassis is constructed of investment cast steel. Exit devices have evolved to incorporate rail style device using forward mounted pushpad. Any horizontal force on the pad will release the door.
There are three common types of exit devices: rim, mortise lock and vertical rod. Most common is the rim exit device that was probably named “rim” device as their latching mechanism is very similar to the rim locks sold in the East and Midwest during the early 20th century. Both the rim lock and the rim exit device are surface mounted on the secured side of the door. The rim exit device is a self-contained door lock mechanism. The latch bolt is located within the center case or chassis.
Rim exit devices have a surface-mounted latch or bolt that slides over the surface-mounted strike. The more common latch is a Pullman style that swings back at an angle as the bar or pushpad is depressed. The latch is located at the front edge of the center case. A deadlatching mechanism prevents the latch from being forcibly retracted in order to gain unauthorized access. Rim exit devices can be equipped with exterior trim containing a lock cylinder.
The bolt style rim exit device is a relatively new introduction sold through several exit device manufacturers including the Corbin Russwin ED5200S SecureBolt™. When locked, the deadbolt style latch extends onto the strike, limiting the space between the bolt and the strike.
The mortise lock style exit device incorporates a mortise lock normally without deadbolt mounted in the door pocket. The mortise lock is part of the exit device. A standard mortise lock is not designed to operate as an exit device. When the push bar is pressed, the spindle or tail shaft rotates retracting the latch bolt, permitting the door to swing out. Mortise lock exit devices can be equipped with exterior trim containing a lock cylinder. The exit device is mounted onto the interior side of the door with the mortise lock mortised into the door edge.
Although mortise lock exit devices can be installed onto single door openings, the mortise lock exit device is often installed onto the active leaf of a pair of doors. The inactive leaf can have a vertical rod exit device or flush bolts that secure the pair of doors within the opening if there is no mullion.
Vertical rod exit devices are available in the concealed or surface versions. The rods connect the device’s pushpad to the top and bottom latches. Vertical rod exit devices can be configured as top and bottom rod, or top rod only, commonly known as Less Bottom Rod (LBR). LBR exit device installations are normally for interior or doors within a secured area. For specifics on the applications of LBR exit devices, see the IBC 2009 codes.
Von Duprin has introduced the Concealed Vertical Cable Systems for fire rated and non-fire rated openings using the 98/9949 Series and the 33A/35A49 Series exit devices. In place of the rods, a cable is run from the device chassis to the top latch. Then, a second cable is run from the top latch to the bottom latch.