Introduction to Fire Safety Management

Introduction to Fire Safety Management
door when closed. The device can be released when the
bar (positioned horizontally across the inside face of the
door) is moved anywhere along its length in the direction
of travel in an arc downwards.
Escape mortice deadlocks – this type of
mechanism is widely used. On the inside there is a simple
turn snib which unlocks the bolt and on the outside the
mechanism is key operated. When the door remains
unlocked a door closer will be required to hold the door
in the closed position.
Cylinder mortice deadlocks – this type of
mechanism (Yale) is satisfactory providing the cylinder
has a thumbturn, which can be installed on the inside
of the door. The fi re authority does not recommend the
type which is key operated on both sides for any class
of emergency escape door, unless there is a separate
method of releasing the lock in an emergency.
Non-deadlocking mortice nightlatches – this type
of mechanism is also suitable; a normal door handle,
a push handle (Fig. 9.37) or a thumbturn provides an
easy means of escape. Care should be taken to avoid
Figure 9.36 An example of a panic device
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specifying any type that permits the handle on the inside
to be locked. Some models allow the latchbolt to be
retained in the unlocked position. If this facility is used a
door closer may be necessary to hold the door closed.
Break glass tube/panel – this is simple to operate
in an emergency. The bolt securing the door in the frame
is held in position by the glass tube or panel. The bolt is
spring loaded so that immediately the glass is broken it
withdraws from the frame and leaves the door open. This
type of device is usually supplied with a hammer on a
chain that is fi xed alongside it to ensure there is no need
to search for an implement with which to break the glass.
The mortice version of this type of lock should not
be used on doors which are fi re resisting because the
glass panel would adversely affect the fi re performance
of the door. Both types can be opened without the need
to break the glass. The glass tube can be removed once
a padlock is opened but access is only possible from
the side of the door on which the bolt is mounted. The
glass panel type can be fi tted with a special strike plate
that allows the door to be opened from either side by
the use of the key.
The glass panel is not affected. Both models can
provide emergency escape from both sides of the
door. There are reservations about these devices and
careful consideration should be given to their use. In
situations where smoke has fi lled the area it would be
diffi cult to locate the bolts, particularly if they are fi tted
at the top of the door. It is, therefore, recommended that
if they have to be used they are fi tted no higher than 1
metre from the fl oor level. This system is especially not
recommended where the public have access.
Break glass locks – breaking the glass or smashing
the fragile plastic dome allows access to a handle or
turn. Both locks can provide escape from either side of
the door. Some can be used by key holders as a pass
door from either side of the door. Also by use of a special
key the latchbolt can be retained in the withdrawn
position allowing the door to be pushed open until such
time as the latchbolt is released and the door closed. In
Figure 9.37 Example of a push handle Figure 9.38 An example of a break glass tube