The proscenium opening between auditorium and stage shall have a curtain made of incombustible materials constructed and installed to lap the masonry opening not less than eighteen (18") inches on each side and two feet (2'-0") at the top and to intercept flame and smoke and prevent glow from a severe fire on the stage from showing on the auditorium side for a sufficient length of time to permit the safe exit of all persons from the theatre. The period of protection shall not be less than fifteen (15) minutes. The emergency closing of the curtain in case of fire shall be effected by gravity.
66. General Design of Frame:
This curtain shall be made in two (2) sections (upper and lower) and each section shall have a rigid frame of steel covered with asbestos cloth on both auditorium and stage sides.
67. General Design of Frame: (Continued)
68. Covering:
Both the auditorium and stage side of the framework shall be covered with a brass wire re-reinforced close-woven asbestos cloth. The cloth shall have a content of eighty-five (85) percent asbestos and shall weigh 3.42 lbs. per square yard. All strips of cloth shall be in one continuous length of the full height of the curtain. That stripe of cloth shall be lapped not less than one (l") inch and sewed with two (2) lines of stitching of asbestos thread, which shall be of the same or greater strength than the yarns of the cloth. The asbestos cloth covering shall be secured by a clamping strip of one and one- quarter inch by five-sixteenths inch (1-1/4" x 5/16") half oval iron, bolted six (6") inches on centers on all sides to the outside members of the frame.
69. The bottom of the upper section shall be covered with only a double thickness of the same asbestos cloth as used on the face of the curtain without any pad.
70. Smoke Pocket and Guides:
The sides of the curtain shall run in and be guided throughout its travel by smoke pockets and rigid steel guides. The smoke pockets shall extend from the stage floor to a height of not less than one hundred and two feet and nine inches (102'9"). The smoke pocket shall be made of not less than twenty-eight by one-half inch (28" x 1/2") plate; on the wall edge there shall be a four inch by four inch by three-eighths inch (4" x 4" x 3/8") angle and on the outer edge two and one-half by tow and one-half by three eights (2-1/2" x 2-1/2" by 3/8") angle attached to which shall be and eighteen by three-eighths inch (18" x 3/8") plate. The guide shall be built integral with the smoke pocket and shall be not less than three inch by three inch by three-eights inch (3" x 3" x 3/8") angle. The guide for the lower section shall be continuous for the full height of the smoke pocket. The guide for the upper section shall extend from the top of the smoke pocket and continue down as far as the bottom member of the upper section when this section is in closed position.
71. At this point, there shall be a heavy seat angle on which the lower member of the upper section shall rest when at its closed position. On the eighteen inch by three-eights inch (18" x 3/8") plate, there shall be a one and one-half (1-1/2") inch smoke stop. This stop angle shall extend from stage floor to a height four (4'0") feet higher than the proscenium arch. The smoke pockets shall be securely bolted in place every four (4'0") feet to wall anchors.