At a recent jobsite, a pair of storefront doors were equipped with a lock cylinder and deadbolt in one leaf and flushbolts in the other and a low energy door operator.
The objectives were to provide:
- A means of automatically locking and unlocking the doors on a schedule
- A means of gaining access after hours when the doors were locked
- A means of locally overriding the locks with a lock PIN code and an unlock PIN code. Whichever code was used, the doors would revert back to the daily schedule at the next scheduled event. (If the doors were locally unlocked, they would relock at midnight; if the doors were locally locked, they would unlock on the next scheduled open time).
The client wanted the locking solution to be a positive latching so the doors would remain secure if there was a power failure.
Control of the door schedule and access control would be by the same electronic access control (EAC) system already controlling other buildings managed by the client. Therefore the access control hardware and credential type (proximity cards) were pre-defined.
To achieve an electrically controlled, positive latching solution which provided for free egress at all times, the customer was comfortable with the level of security upper rods would provide and additionally wanted the ability to mechanically dog the exit devices. I selected Von Duprin SVR LBR with EL option.
Exit devices are available in rim, mortise lock, surface, and concealed vertical rod mountings.
Exit devices can be Fire Rated, for use on Fire Door Assemblies. Using a fire rated exit device on a non-fire rated door, does not upgrade the door to a fire door. However using a non fire-rated exit device on a fire door nullifies its fire rating.
There are numerous differences in performance and features between regular panic hardware and fire rated exit devices. The design and construction of the door is also as important as the exit device being used.
Numerous on-line resources address these issues, as well as NFPA 80: Standard for Fire Doors and Other Opening Protectives. For more information, see http://www.nfpa.org.
Rim and mortise exits are similar in that the latching mechanism is on the edge of the door. Vertical rod exits latch at the top or at the top and bottom of the door.
Generally speaking, a rim or mortise exit device is unsuitable for a pair of doors, since one door would have to be locked (bolted) so the latch of the active door could secure the opening.
If one of the doors is inactive, it is not available for emergency egress, and therefore would defeat the reason for having an exit device on the opening in the first place.
The correct answer to issues involving situations where one leaf of a pair of doors would be bolted shut is to be found in the building code and the Local Authority Having Jurisdiction’s (LAHJ) interpretation of it as it applies to the particular opening.
When upgrading an existing opening, it is best to verify what you have in mind with the LAHJ before committing to do work or beginning to modify an opening.
The locking features of the exit device are determined by the particular device and application. For the overwhelming majority of installations, the exit device will always provide a means of free egress. While the door is closed, it is latched, but when the bar is pressed, it unlatches.
Sometimes a door is exit only, and there will be no lever trim on the exterior of the door. So from the exterior of the door, it is locked because there is no easy way (trim) to unlatch it.
A lock cylinder can be provided on the exterior of the door as a means of gaining entry. Lever trim can be provided which can also be used to gain entry. Lever trim is usually provided with a cylinder as well for manual override.
Electrically controlling a rim or mortise exit device can be accomplished a number of ways.