Motion Picture Herald (Nov-Dec 1944)

eather. In a good layout the returns from pe coils are connected in parallel with the feam mains, and a separate trap for each bank |t coils which have a separate steam control jtalve. \ In steam and return pipes, proper provision -flould be made for expansion and contraction Kie to changes in temperature. Steam lines xpand as much as 1^ inches in 100 feet, and ne return lines about inch. It should be emembered that there is a greater expansion cfi the piping at the time of erection and the ^.:,rst steam run, than after the theatre has been iib ser\'ice for some time. However, proper rtrovision should be made to compensate for ( lis temperature effect by the installation of li'inff or expansion joints. The swing joints i Tould be used on riser and radiator runouts, rrd the expansion joints in tight places, such _5 pipe tunnels, furred walls, etc. lEATlNG COIL PIPING Indirect radiators or coils should always : ave a flow and return pipe, and when a oneiipe system is employ ed the return riser must :e entered into a return main below the water : ne. WTien a vacuum system is used, it is rovided with an exhausting device for pro: ucing a vacuum either on the return or on a Jpe run connecting to the air valves. Generally, in the vacuum system a pump is applied 'o the return pipe and by its action the pres ure is removed from the entire system. This : ype of system is usually designed so that it oes not exceed J^^-pound drop per 100 feet, ' T more than 1 pound total pressure drop in -'he system. The mains are pitched from the ;'oiler about Y2 inch in 10 feet and should not ,:«e less than 2 inches in diameter. When the u 'f ^ that the application of black or very dark paint to exposed radiators, heat piping, etc., will help to transmit the heat better? that white, light blue and light green paints applied to heating surfaces are less durable than yellow, dark grey, dark green, black, etc.? that ordinary aluminum paint offers more resistance tq heat transfer when applied to radiators, heating pipes, etc., than does ordinary 9II and lead paint? that rust, dirt and scale can be removed more easily from air valves, pressure reducing valves, thermostatic traps, and valves in general by soaking them in carbon tetrachloride? steam main is 3 inches in diameter or over at the boiler or pressure reducing valve, its size should be 2y2 inches at the far end of the run. It is considered good practice to have the supply main, riser or bianch to a riser, dripped separately through a trap into the vacuum return. In a vacuum system, a connection should not be made between the steam and return . sides without a trap to prevent the steam from bypassing into the return line. Cast iron, low pressure boilers have several tapped outlets in the top for the use of reducing the velocity of the steam in the vertical risers and to permit the trapped water to return to the boiler instead of being forced into the steam main and then dripped. Some steel heating boilers have only one steam outlet in the top, but the latest and best types have two such outlets, which help reduce the velocity in the steam uptake. A heating installation should be designed and sized correctly and installed with extreme care, having proper connections and runouts that allow for expansion, thermostatic traps that are protected from scale, pressure reducing valves that have strainers, and sufficient number of drips at the necessary points. PLAN NOW! {Continued from page 13) delays. The post-war theatre will be, like the post-war automobile, refrigerator, etc., just about what we had before the war — in all essentials, precisely the same. Most of the improvements that will soon be available when industry can return to its regular interests, are known and can be taken into consideration now in planning. But some of importance in construction generally — lighter steel, for example— are of little or no significance to theatres. For revolutions in the arts of peace we can look to a world in peace rather than to a world at war. Theatre operators can safely do their planning now. And they should. There is much to be done if the motion picture is to hold its place through the post-war years. • • • PROVED DEPENDABLE Acclaimed hy Theatre Owners Busy theatre owners and managers are enthusiastic about UNIVENDOR'S consistent smooth performance. With help scarce and replacements hard to obtain, they're especially grateful for the freedom from maintenance and service problems that UNIVENDOR makes possible. Now, more than ever, the reliable UNIVENDOR is proving itself the finest in candy vendors. Plan now on installing UNIVENDOR in your theatre after Victory. STONER MFC. CORP. Aurora, JBEHER THEATRES, DECEMBER 9, 1944 19