Building Design and Construction Handbook - Merritt - Ventech!

11.132 SECTION ELEVEN
When floor-type checking and closing devices are used, floor conditions should
be carefully determined in order that there will be sufficient unobstructed depth
available for their installation.
To get maximum performance from any door closer, it must be of ample size
to meet the conditions imposed on it. If abnormal conditions exist, such as drafts
or severe traffic, a closer of larger than the normal capacity should be employed.
Installing too small a closer is an invitation to trouble. Manufacturers’ charts should
be used to determine the proper sizes and types of closers to suit door sizes and
job conditions.
It is very important that door closers be installed precisely as recommended by
the manufacturer. Experience has shown that a large percentage of troubles with
closers results from disregard of mounting instructions.
In response to various code requirements for room-to-corridor protection, closer
manufacturers have produced products that provide automatic door closing but still
allow flexibility. These units permit the door to be held open in many locations of
hold-open and yet upon a signal from a smoke detector, the hold-open mechanism
disengages and the closer causes the door to close. A similar type of unit incorporates
a device allowing the door to swing free as though it were not equipped
with a door closer. As with the multiple-point hold-open device just described, the
‘swing-free’ model, upon a signal from a smoke detector, cancels the closer nullifying
device and the closer causes the door to close. These units are suitable in a
variety of occupancies, particularly institutional.
Barrier-free provisions for disabled people dictate certain minimum opening resistance
of doors. Depending upon the jurisdiction and location of doors, these
forces range from a 5-lb force maximum to a 15-lb force maximum. There will be
instances, because of the door size or air-pressure conditions, when the necessary
closing force exerted by the closer to overcome these conditions will create opening
resistance in excess of what is permitted. Power-operated doors or doors with a
power assist specially made to solve this problem are recommended as a practical
solution.
11.67 LOCKS, LATCHES, AND KEYS
The function of locks and latches is to hold doors in a closed position. Those known
as rim locks or latches are fastened on the surface of the door. The ones that are
mortised into the edge of the door are known as mortise locks (Fig. 11.78) or
latches.
When the locking bolt is beveled, the device is usually referred to as a latch
bolt; such a bolt automatically slides into position when the door is closed. A latch
is usually operated by a knob or lever. Sometimes it may be opened with a key on
the other side. Night latches came to be so called because they are generally used
at night with other ordinary locks to give additional security.
Latches must take into account the hand of the door so the bevel will be right.
A large percentage of latches are ‘‘reversible’’—that is, they may be used on a
right- or left-handed door (Art. 11.82). It is well, however, when ordering any lock
to specify the hand of the door on which it is to be used.
If when you are standing outside the door the hinges are to your right and the
door opens away from you, it is a right-hand, regular-bevel door; if the door opens
toward you, it is a right-hand, reverse-bevel door. Similarly, if when you are outside