Motion Picture Herald (Apr-Jun 1931)

62 Better Theatres Section April 11, 1931 EQUIPMENT AFFAIRS Reports About Products and People in the Field of Theatre Equipment and Supplies New Cooling System ENGINEERS of the Supreme Heater & Ventilating Corporation of St. Louis, who have been working during the past three years on a physical principle in which the temperature of the air is actually reduced through the use of a process of evaporation of water, have now incorporated their ideas in a ncAv Supreme cooling system. The system consists of a slow-speed, lowpower blower fan, a five-speed electric controller, the well known Supreme Automatic Oscillating Air Diffuser, and the new evaporator unit. The air induced into the system by suction of the blower fan enters the evaporator unit at low velocity. It is there forced into contact Avith a completely atomized mist, a perfect barrier of interlocking spray of water at no less than twenty pounds of nozzle pressure. The process of evaporation begins immediately — from the fine spray, the surface of the larger drops of water and from the surface of the bed of water in the supply tank. In this process of evaporation heat transfer from the water to the air takes place. The circulating Conducted by G. J. Reid water is cooled to approximately the wet bulb temperature, which with air containing the average percentage of relative humidity would be many degrees below the dry bulb or ordinary thermometer temperature. When the circulating water reaches this wet bulb temperature it remains constant as long as the entering air temperature and relative humidity do not vary. In the process the water is circulated, sprayed and cooled. Only a certain amount of the air passing through the spray chamber, or evaporator, is necessary in this evaporation for cooling the water. The greater portion of the air, with only a partial amount of the relative humidity it is capable of carrying, passes through the evaporator without absorbing any moisture. In fact, we are told, it has been found that this portion even gives up some of its moisture while being cooled by contact with the cold circulating atomized water. There is, therefore, according to Supreme Engineers, a mixture of air entering the theatre, a small volume that has performed the work of evaporation in cooling the circulating water, and a large volume that has performed no work, but has been cooled by contact with the cold Avater and hence has given off its heat to the water. The small volume of air engaged in the evaporation process becomes completely saturated. The air is delivered into the auditorium at a fairly high velocity. As soon as this mixture of cooled air containing a fraction of the moisture it can hold, and the small volume of saturated air enters the theatre, the work of evaporation and absorbtion of the moisture in the auditorium and on the bodies of the occupants occurs. This activity sets up the effective temperature (actual coolness rather than the reading on the ordinary thermometer). One of the essentials of the system is easy exit for the air that is constantly inducted into the theatre through the system. Normally in theatres not having balconies the exit doors provide ample opening for the escape of the air. Where there is a balcony, additional provisions must be made for the positive and rapid removal of the air. Otherwise moisture will build up in the auditorium that will defeat the entire plan of the system. New Condenser System AN interesting cooperative efifort on the part of two companies has resulted in a new projection light condensing system with special lamp and housing. To appreciate the lines along which this effort was conducted and what has been accomplished, it may be well to trace briefly the conditions that brought it about. Of course, sound was at the bottom of it. The sound screen brought loss of image brightness, of course, and the theatre which formerly projected a bright picture found its screen considerably darkened after the installation of sound equipment. As a result carbons were frequently overloaded, larger sizes of carbons were tried out, and in some cases the current carrying capacities of standard carbons were increased. The research department of Bausch and Lomb attacked the situation by developing a new light condensing system consisting in a 55^-inch diameter collector lens, with a cylindrically ground curve on the rear, or collecting, surface, in combination with a six-inch parabolic converging lens, the special curves of which allowed the full diameter to be employed with an increase, it has been claimed, of more than 50 per cent in illumination. And now Hall & Connolly, of New York, manufacturers of high intensity lamps, has designed a lamp and housing to accommodate these condensers. The