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 mechanical bolt with a common knobset hardware or vertical push bar device.
The keeper channel catches or releases the bolt, depending upon the lock
status. The strike is either surface or recess mounted on the door frame.
Considerations for device choice include composition of the door frame, size
and shape of latch bolt, and the holding force or potential for abuse of the
door lock. Recommendations for locking hardware with access control systems
usually require the heavy-duty type of locks. Options for this device
include latch bolt monitor, indicating whether the bolt is extended into the
strike; lock cam monitor, indicating whether or not the strike is in a
locked position; a combination of both features and additional switches,
indicating if door is shut and locked, and an interlock feature to permit
only one door in a series to be unlocked at a time as in man-trap or energy
conservation foyer applications.
5.2.3.2 Electric Bolts. Electric bolts provide positive locking by pushing
a solenoid-operated rod into a hole in the door edge. This device requires
critical alignment between the bolt and the locking strike. This device is
used generally for interior door application, since the electric bolt may
not meet certain safety code regulations for egress doors. In U.S. Navy
applications, electric bolts shall have a minimum throw of one inch.
5.2.3.3 Electromagnetic Lock. The electromagnetic lock consists of a power
magnet and a steel plate. The magnet is mounted to the door frame in
alignment with the steel plate in order to provide a strong or hardened area
to apply magnetic force. This device is inherently fail safe since power is
interrupted to unlock, and fail-secure types maintain power with backup
battery supply. Minor variations in door alignment and problems associated
with door settling and warping can be addressed by use of this device.
Pairs of doors can be secured by a single device if both swing in the same
direction (outswing or inswing).
5.2.3.4 Fail-Safe/Fail-Secure. There are two operations of an electric
door lock if power is removed. These two operations are termed Fail-Safe
and Fail-Secure as follows: if the power fails, the lock becomes either SAFE
for access/egress or SECURE - locked. Considerations in application of
these two types is often due to fire code, electrical code, or activity
regulations which consider that in the event of an emergency - fire or
catastrophe - the human seeking to exit is not capable of rapid thought and
logical reasoning and thus requires a simple, usually entirely mechanical,
means of exit. The spirit of this requirement is to assure that speedy exit
is accomplished without having to read directions or depend upon electrical
or electromechanical devices which may fail due to the emergency condition.
5.2.4 Remote (Control) Units. The remote control unit is that component of
the access control system which translates communications and performs
interface tasks between credential readers, electric door locks, and the
central control unit. This intermediate device is usually subject to
distance constraints and is often located to accommodate line length from
readers and central control unit. The functions of a controller include
interpretation of coded information to the central control unit. If the
facility code criteria
13.02-76
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