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For Free Exit doors,
use electric strike,existing door furniture
can often be utilised. Or a magnectic lock with a push button exit switch.
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Use an electromagnetic
lock if you want to prevent free exit or to control exit
with a card reader or a keypad.
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The most common locking devices used in the access control
industry are electric door strikes and electro-magnetic
locks. To select which locking device should be used on
a specific job, the installer must begin with an evaluation
that will take into account not only the security requirements,
but also the regulations imposed by local or national
authorities.
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| Electric strikes
Because
of potential regulations affecting the use of other devices,
a door strike will generally be the most economical locking
mechanism.
There are two basic types:
1) fail locked (fail-secure) which means
the strike will be locked when you remove power
2) Fail open (fail safe) which means
the strike will be open when power removed (i.e. if fire
alarm activated)
These specifications correspond to the requirements
of access control. Electric strikes are generally more
difficult to install than electro-magnetic locks.
Double doors
On double doors, the door strike will be installed
on the inactive door which should be bolted down. A door
cord or electric-conductive hinge will carry the power
to the strike. Or each door can be fitted with a strike
fitted to the door header of each leaf.
Special situations
It may not be possible to install door strikes
on special doors such as full glass doors. The only alternative
may be to install an electro-magnetic lock. |
Electromagnetic locks
When the exit must be controlled, it is necessary to
provide a fail-safe device, such as an electromagnetic
lock, that will keep the door locked not only on the entry
side but also on the exit side of the door.
Other locking devices
Mechanical devices (such as electric deadbolts) that prevent
free exit are usually not permitted for use in access
control applications., unless they fail open or have a exit handle.
Controlled entry and Free exit
A controlled door with "Free Exit" means that
a reader or keypad is installed outside the controlled
area identifying users as they come in but, no control
is made during exit of the area.
Controlled exit
A controlled door with "Controlled Exit" means
that readers or keypads are installed on both sides of
the controlled door. The users are authorized on entry
and exit of the area. Sometimes, the controlled exit is
enforced only outside of normal work hours.
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