Modern Theatre Construction (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ...Heated or vitiated air rises because of this lessened density, and the simplest method of exhausting such air is by means of mechanical exhaust ventilators installed in the ceiling. There are many forms of these automatic ventilators, but the best in common use is the siphon type. A reliable means also in exhaust ventilation is a propeller fan encased in a penthouse equipped with a shutter arrangement that closes and overlaps by gravity and opens with the force of the outgoing air current. If it be necessary to employ a duct to convey exhausted air from the blower or fan to the outside air the duct must be equal in diameter to the crosssection of the fan. As vitiated air is expelled from the auditorium by blowers or fans, a lower pressure is created in the audience hall than that which exists outside, and fresh air will naturally rush in through the doors and fresh air openings to replace what is forced out. While this may be very satisfactory in the summer months, the draughts of cold air would be decidedly uncomfortable in the colder months. This in a measure may be corrected by the introduction of fresh air through a lobby heated by radiators or through fresh air inlets conveniently arranged behind wall radiators. However, the best system for heating and ven-The Plenum tilating a theatre is the one termed the plenum or forced-draught system, where the air is taken from the outside into an isolated chamber, there heated or cooled for use, and forced by blower fans into the auditorium. This chamber may be established either at the top of the auditorium, or in the basement underneath as shown on the heating diagram on Page 145. Its adoption entails a modification of the direct radiation system, combined with other methods, and provides...