Motion Picture Herald (Nov-Dec 1944)

grade, smooth, and even toward the drain to the sewage line. It is very important that this drain be installed in the floor, but it should be so located far enough from the boiler so that there will be the least chance blocking up with ashes and coal dust. WHAT KIND OF SYSTEM? A general outline and discussion of the various systems used for the heating of theatres will enable the average layman to familiarize himself with the make-up of an ordinary heating plant (the details of installation may be left to the judgment of the heating contractor, and the actual design of a particular system to a heating engineer). Steam-heating layouts are of three types. The first is the gravity, or indirect radiation; the second is the vacuum system, using either direct or indirect radiation ; the third is the high-pressure system having gravity circulation with return-trap, or pump, from the radiators or heating coils used in a central fan or forced-blast system of heating. A steam heating plant may be divided into four distinct parts: (1) boiler; (2) radiators or coils; (3) the supply and return jjipe ducts for carrying the hot-blast air. The types of boilers used in theatres are (1) horizontal tubular; (2) fire-box; (3) sectional boilers, having vertical or horizontal sections. The horizontal tubular boiler has been used extensively in the past for heating large buildings, especially where large quantities of steam are required for hot-blast systems. This type of boiler is quite efficient for radiators — say, over 3,000 square feet of radiating area — and Do you want Greater Screen Brilliancy? The B&L Super Cinephor f:2 .0 Projection Lens is coated with "Balcote." This is the revolutionary lens coating that eliminates internal "flare" and permits the passage of 30% more of the light . . . that means screen images which are 30% brighter. This, with precision anastigmatic correction, means not only greater screen brilliancy but better image quality, color purity and contrast as well. Cinephor Series II offers similar projection efficiency in the longer focal lengths (S'A" to 9") Cinephor Lenses f:2.0 provide excellent correction and high speed at moderate price. Focal lengths from 3V2" to 5" . . . in No. 2 barrel. Cinephor Series I is a standard projection lens used in many American theatres. Production for victory has unquestioned priority. While this may cause inconvenience, delay, and sacrifice in filling civilian orders, we know it has the unqualified endorsement of everyone with whom America comes first. Bausch & Lomb Cinephor and Super Cinephor lenses are sold by National Theater Supply Co. and also by leading independent theater supply houses. BAUSCH & LOMB OPTICAL CO., ROCHESTER 2, N. Y. EST. 1853 is well adapted to the burning of soft coal I However, for high-pressure work, this type of boiler is provided with man-holes having strongly reinforced edges, while the heads above the tubes have strong, durable braces tc hold safely the high pressure from the insidei With low-pressure steam, and other things being equal, the chance of an explosion is verj*!' small. The size of this particular boiler runr from 3 feet in diameter and 8 feet long, to S feet in diameter and 20 feet long. The size ol the tubes where hard coal is used is 3 incheC in boilers up to 12 feet long; over this length 4 inch tubes are used. Where soft coal i;^ burned, the diameter of the tubes is 3 inche; regardless of the size of the boiler. " This type of boiler is installed with half fronts and full-fronts. For the half-front setting, the front end extends somewhat beyon the brick work and is covered with a cast iroii frame with two access doors to the flues. Fo; a full front type, a cast iron front runs th full width of the boiler and extends from tht floor to the top of the brick setting. . (Ir theatres constructed in recent years, the hori" zontal tubular boiler has been less often in stalled than formerly.) The fire-box boiler is similar to a horizon tal tubular boiler except that it has a firebox at the front end. This fire-box has doubl walls, and the space between these walls i filled with water so that a greater percentag of heat is generated than is possible with thi regular tubular boiler. This type of boile handles 1,500 to 3,500 feet of direct radiatioi and is well suited to the burning of hard coa or coke. Fire-box boilers have the same brici, setting as ordinary horizontal tubular boilers^ P The sectional cast iron boilers have nov generally replaced the tubular boilers for heat ing theatres, principally because of their safe ty from explosions. In case an explosioi should occur in a sectional boiler, it woulc in all probability be confined to only abou] two sections. 16 SECTrONAL BOILER ADVANTAGES This type of boiler is made up of a num her of vertical sections which are set in fron of each other on a cast iron base which form the ash pit. In one type of boiler the sec tions are connected together by push-nipple fitting tightly into adjacent sections, while ii another type each section is connected to thre drums, one above the boiler, and one on eac side near the bottom. The former type i called a push-nipple boiler, the latter screw nipple. The push-nipple boiler is more easil installed and it affords a freer circulation o steam and water ; however, in the event section breaks, the entire plant must be shu down until a new section can be installecF On the other hand, if a section of the screw' nipple boiler goes, it can be disconnected fron the drums and the openings plugged, permit ting the boiler to operate temporarily withou removal immediately of the disabled sectior An advantage of sectional boilers is tha the capacity can be varied, within certain lim its, by increasing or decreasing the number o sections. In external appearance nearly a) vertical sectional boilers are quite alike, al though the arrangement of the flues or pas sages for the heat dififer somewhat in diffei ent makes. This applies equally well to stee fire tube boilers. ' As a general rule, those boilers which hav the greatest amount of heating surface in pro' BEHER THEATRES, DECEMBER 9. 194