Motion Picture News (Oct-Dec 1930)

72 Motion Picture News October 4 , 1930 Carbon Dioxide for Theatre Cooling; An Exposition of How System Works Official of Carbon Dioxide Division of Frick Company of Waynesboro, Pa., Describes the System and Lets Reader Draw Own Conclusions By A. N. CHANDLER COMFORTABLE indoor conditions are not provided by temperature alone. Humidity and air movement have much influence, and each application is a problem in itself. The theatre, department store and office building differ from each other in the character of work done, kind of occupants, and number per unit of floor area. In the theatre the audience is still for a period ranging from two to three hours. Of course, people are coming and going at all times but their number is relatively small in proportion to the total number which is seated. People who are sitting still present an entirely different problem from those in a department store where they are moving about. Those in a theatre should feel no draughts or cold air currents. Occupants of office buildings require special consideration. Here there are relatively few in number in each office. They must get a supply of conditioned air of proper temperature and humidity to suit their needs. Each office presents a different problem. In laying out nearly all air conditioning work, space for the equipment is at a premium. Often it has to be fitted in anywhere regardless of whether it is the ideal place or not. Often it is an afterthought or lias to be applied to an existing building, in which case it presents a very difficult problem. Not only is space for the refrigerating apparatus frequently hard to find but to make room for installation of the air ducts is another problem. Carbon Dioxide Compressors There are several kinds of refrigerating apparatus which can be applied to air conditioning work. Some of them provide a greater refrigeration tonnage than others per area of floor space occupied. Figure 1 shows an installation of two carbon dioxide compressors placed in a theater near New York City. These require a floor space of 300 sq. ft. and head room of 9 ft.-6 in. Each is the totally enclosed type and has no FIGURE 1 One of the two large carbon dioxide^ compressors which furnish refrigeration for air conditioning the Newark theatre, Newark, N. J. Double-pipe condensors may be seen in the background vertical shaft stuffing box. The stuffing box is of the horizontal rotating type. The compressor is equipped with an oil pump which keeps the bearing under oil pressure of from 400 to 500 pounds at all times. The stuffing box is kept cool by means of a gland in which gas from the suction line is allowed to expand. Figure 2 shows a cross section of a typical enclosed type carbon dioxide compressor. The thrust bearing takes the crank shaft thrust and equalizes the pressure between the crank case and the atmosphere. It operates at all times under oil pressure. Each compressor is built with a starting by-pass and safety valve. This valve is of the spring type which blows at 1,500 pounds pressure and repeats when the pressure is relieved from 200 to 300 pounds. In order to eliminate noise the carbon dioxide compressor and motor are often placed on foundations of cork. In other cases, the foundation is built in a pit which has been lined with cork. Carbon Dioxide Condensers One type of CO2 condenser consists of an eight-inch double extra heavy pipe with seven lj^-in. pipes welded into the tube head. The water heads are of cast iron and divide the shell into several water passes. Figure 3 shows a view of such a condenser. These can be arranged any number of pipes high depending on head room available. They can be placed on 18-in. horizontal centers. Each shell can be arranged to take from 20 to 40 gallons of water per minute, depending upon the range of temperatures desired or work to be done. The water leaving the condenser is within a few degress of the carbon dioxide liquid temperature off the condenser. As an example, an installation requiring 350 tons refrigeration and using shell and tube condensers could be arranged in a floor space 7 feet wide by 22 feet long. Furthermore, this space allows room for carbon dioxide and water headers. On this installation, the head room required would be 11 feet 6 inches. Another system is a typical carbon dioxide double pipe welded condenser. It is made up of 1J4 inch water pipes throughout. The four top sections are made up of 2"^ inch extra heavy pipe and the remaining eight pipes of 2 inch extra heavy pipe. The 2}4 inch and the 2 inch pipes are welded to the 1J4 inch pipes at each end. The reason for the larger top section is to absorb the pulsation of the carbon dioxide gas from the compressor which causes a cushioning effect. The water is so arranged that the coolest water comes into contact with the coolest gas, making the temperature of the carbon dioxide liquid off the condenser near the initial water temperature. Figure 1 shows several stands of double pipe welded condensers. It is the general practice to supply each