Motion Picture Herald (Jan-Feb 1945)

II alloy pipes are best suited for water supply as they resist corrosion and their inside free areas remain practically constant. In figuring i galvanized pipe, about 30 percent more should be allowed over the corrosion resistant type, as the inside area of galvanized pipe may be j decreased as much as 20 percent after a period ! of years in usage. The advantages of brass and copper pipe easily outweigh their higher initial cost, which can be reduced considerably by using fittings that can be soldered or j sweated in the erection, thus allowing the use ' of pipes with thin instead of the extra thick walls required in the case of threaded fittings ' or connections. I WHAT KIND OF PIPING? In heating, ventilating and water supply installations there are several difierent types j of piping used, such as alloy metal pipe that has a small amount of copper or manganese j in the steel to offer more resistance to corrosion. Wrought iron pipe which is more corrosion-resisting than ordinary steel pipe, but I somewhat higher in cost. Cast ferrous-metal ; pipe is made of a good grade of cast-iron with j a small alloy of nickel or chromium. The j advantages of this particular type of pipe are I that it can be easily cut, threaded or welded, and it can be manufactured in any length practicable for handling. Wrought steel pipe is used mainly in heating and ventilating work; the material used is a mild steel fabricated by the open-hearth process. When this mild steel is shaped into pipe form and the edges are welded together, it is called a welded-steel pipe and when the pipe is formed or drawn from a solid bar it is called a seamless-steel pipe. The seamlesssteel pipe has the greatest advantages in that it has great strength, will not split open when sharply bent (as is the case sometimes with welded pipes), and it is very practicable for high-pressure work, coil makeup or cold bending in any forming operation. Lead pipe is quite practicable for use in water supply systems in that it offers the least resistance to the flow, and can be easily bent or curved. It is generally considered more durable underground than galvanized iron pipe provided it is well protected from excessive weightloads. When lead pipe is selected for runs from the city mains or at traps, only an extra-strong grade should be used. If galvanized iron or steel pipes are buried in the ground, they should be protected by coatings of asphaltum applied hot, then covered with tar paper or asphaltic-fabric wrappings. PIPING FOR UPWARD FEED In sizing up the piping system in the theatre, it should be ascertained beforehand if an up-feed riser system is needed to furnish the proper quantity of water at the right pressure to every fixture or plumbing equipment. In the up-feed riser layout, the drop in pressure as the top of the run is reached, must be figured because of the natural reduction in the gravity pressure, plus the pipe resistance ^nd pipe fittings. These items in the up-feed system produce a drop in the water flow far in excess of that produced under the same conditions in a down-feed system. In the up-feed riser layout, the pipe run IS sized from the minimum pressure of the NEW RCA BOOK ON THEATRE TELEVISION RCA, pioneer of 25 years in the field of electronics, brought television to the New York World's Fair in 1939, and to the theatre in 1941 at a large screen showing. With a realization of the great interest created by this new great potential entertainment medium, RCA Service Company has prepared a booklet of especial interest to members of the theatre industry. The RCA Television Handbook for Projectionists will help you prepare for TT* day through a thorough understanding of what makes TT click. Written essentially for the projectionist, *Tkeatre TeUvision. BUY MORE WAR BONDS it also contains an interesting discussion of developments on this timely subject of importance to theatre management. Based on RCA's lengthy experience in the development of theatre television, you'll find plenty of good solid information to help you become better acquainted with this most important development. Whether you are theatre owner, manager, or projectionist, be sure you get a copy. Send for your free copy today! Address: RCA Service Company, Inc., Box 70-78B. Camden, New Jersey. RCA SERVICE COMPANY, INC. A Radio Corporation of America Subsidiary Don't wait — get your copy of this informative book on Theatre Television right away. No obligation. RCA SERVICE COMPANY, Inc., Box 70-78B, Camden, M, J. Name Theatre Are you: Manager? Projectionist? Address Citv State . . . 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