In factory and similar buildings, it frequently happens that one portion must be separated from another by brick fire-walls and that the openings in these walls have to be closed with tin-covered doors as required by the National Board of Fire Underwriters, the object being to reduce the fire hazard. Wherever possible, these doors are made sliding and arranged so as to close automatically, being hung on a slanting track with an incline of ¾ inch to the foot, and also counterbalanced with weights so that the door will stand at any point, as shown in [Fig. 127]. The cord or rope attached to the weights passes over a pulley and is attached to the door with a fusible link, as at a, which, in case of fire gives way and allows the door to close automatically.
The doors are usually constructed of seasoned white pine or similar non-resinous wood, using three thicknesses of ⅞-inch matched boards, the outside layers to be vertical and inner layers horizontal and thoroughly fastened together with wrought-iron clinch nails, driven in flush and well clinched. The doors are then covered with 14" × 20" IC bright charcoal tin plates of not less than 107 pounds to a box of 112 sheets. All joints are locked ½ inch, without soldering, and nailed under the seams.
The track for these doors is best made of round-edge bar iron or tire steel, ⅜ in. × 3½ in., being bolted to the wall with through bolts having nut and flanged washer on the opposite side, and held from the wall by cast-iron track brackets. The hangers are of wrought iron, ⅜ in. × 3½ in., provided with roller-bearing wheels and are attached to the door with at least two bolts. The binders are of wrought metal, ⅜ in. × 3½ in., with angle flange at back end to notch in the wall and so arranged as to grip and force the door against the wall when closed. In connection with this, a wedge is placed at the end of the lower chafing strip, and, when the door is closed, engages with the stay roll so that the door will be held close to the wall on the opposite side. Two chafing strips of ¾-inch, half-oval metal are placed on back of door with 1" × ⅛" flat strips of same length in front and bolted through the door. Bumper shoes are also used to prevent the binders from mutilating or damaging the tin covering at the points that strike the binders.
90. Door Knockers.—Although the medieval door knockers have been replaced by the modern door and electric bell, they are still used occasionally for decorative purposes, and, when required, they should be selected and specified with the finishing hardware. Door knockers are made in various styles, sizes, and finishes—in iron, brass, or bronze—to match the several designs expressed in hardware. The elaborateness of the designs of this somewhat ornamental piece of hardware is shown in [Fig. 128].
Fig. 128
Fig. 129
91. Water-Closet Door Trim.—The construction of water closets in public buildings has brought forth special hardware to meet the various conditions of convenience, simplicity, and hard usage. In ordinary work, the doors of water-closet compartments are secured with a hook or a barrel bolt, while in the better class of work, as in hotels and public places of this character, mortised thumb or knob bolts or, better, indicator bolts are used.
Indicator bolts, as shown in [Fig. 129], made both mortise and rim, are available for water-closet doors. In either case, the bolts are mortised into or placed on the inside of the door with the indicator case on the outside. The indicator dial has a spindle on the back, and this engages with the knob that operates the bolt. When the bolt is thrown, the indicator shows the word “Engaged,” and when turned back, the word “Open” appears.