EVERY SWINGING FIRE DOOR MUST HAVE A LABELED AUTOMATIC LATCHING DEVICE TO ENGAGE THE STRIKE. Deadlocks may be provided in addition to the latch bolt, except on doors used as a means of egress, where interconnected locks may be used which retract the dead bolt with the latch bolt. Dead bolts may not be used in place of latch bolts. When selecting latching devices, it is important to use the correct length of latch bolt, a requirement that can vary with the door construction and the manufacturer’s fire testing program. It is common for a pair of doors to require a longer latch bolt throw than a single door. The minimum latch bolt length that must be used for any given door is indicated on the fire door label. Some state and city building code authorities allow the use of a “push” and “pull” function on certain fire rated openings. This push/pull function does not include a self-latching device and does not allow a fire door to perform its vital function. Without a latching device the door will not remain closed during a fire. A manufacturer cannot fire label a door prepared only for a push/pull function.