Motion Picture Herald (Sep-Oct 1939)

Air Purity: How to Attain It— —Air-Motion : How to Control It ^ The first of a series on air-conditioning equipnnent, this article continues the group of "plain talks" on air-conditioning begun in the April 29th issue, which now turns to the mechanical facilities for maintenance of the Effective Temperature representing comfort conditions in the theatre EDITED OUT ■ In manuscript, Mr. Boester did not begin his article as it is published. His introduction was something of an aside. Nevertheless, although removing his introductory remarks from the article itself, we certainly did not drop them in the wastebasket. Here they are, deleted but, further than that, unedited: "Before discussing what types of equipment will efficiently maintain desired Effective Temperatures, the writer cannot help pointing out to you readers the merit of the preceding articles in this series, describing what Effective Temperature means in relation to comfort, and how It Is obtained through the simultaneous control of air-motion, air-heat and alr-molsture. "It seems probable that nothing in the history of air-conditioning that has been written or spoken has been as much in point as these articles, not only to you in the theatre business, but also to air-conditioning engineers all over the country. "There Is no question but that the articles heretofore published are a very Intelligent and capable presentation, In non-technical language and approach, of just what happens when we air-conditioning engineers endeavor to provide patron comfort In your theatres — and I should think that, as readers, you would clamor for republication of them In booklet form so that you might have them handy as a guide to the comfort of your patrons." Mr. Boester did not know that there has been, all along, a tentative plan to make the entire series available In booklet form. As for Mr. Boester himself, his previous contributions to Better Theatres will be recalled. He Is a St. Louis engineer who has made a special study of theatre air-conditioning and ventilation, and he has made a number of original contributions to Its technique. — S. S. By CARL F. BOESTER IN ADDITION to the treatmen or conditioning of air by controlling air motion to provide for heat deficiency and air moisture deficiency during the period of winter operation, and by controlling air motion, removing excess air heat and excess air moisture during the summer cycle, there is also — in either cycle — the essential of air purity. This article will briefly discuss air-purity and, in more detail, air-motion, as well as the mechanical equipment required to accomplish and control these two objectives. The treatment of air, in order that it may truly be called "air-conditioning," consists of four functions, or steps, controlled simultaneously. In this latter statement the word simultaneously is very essential. Unless the functions of purifying, circulating (air-motion), heating or cooling, and humidifying or dehumidifying (depending upon the season of the year) are accomplished simultaneously, the air is not really conditioned according to the standards set up by the engineering societies composed of members engaged in air-conditioning engineering. qAiR PURITY As a starting point it is well to consider, first of all, the matter of air purity. Air purity can be broken up into two classifications : ( 1 ) Removal of dust and similar foreign material in the air, and (2) Removal of objectionable odors. The first of these is accomplished 7?ie chanically , but the removal of odors cannot be fully accomplished mechanically, physically or chemically. There is just one true way really to remove all unpleasant odor after it has tainted the air, and that is to dilute the foul air sufficiently with fresh outside air and so render the odors unnoticeable. Odor Elimination The only way to keep the air pure and fresh is to change the air in the theatre entirely at frequent intervals and thus keep down the odor concentration that results from smoking, body odors, etc. It should be remembered that odors very materially irritate patrons to the point that they frequently get headaches and may leave the theatre, attributing the headaches to weak eyes or to "flickering" of the picture, when in reality the irritation is caused by a disagreeable odor affecting the nerves controlling the sense of smell. In order to keep objectionable odors down to a minimum it is essential that approximately 25% of the total air being circulated and distributed to the theatre by the air-conditioning equipment is fresh outside air. // smoking is permitted, this quantity must be increased to a minimum ratio of at least 50%, and in some cases as much as all outside air will be necessary for desirable conditions. Filtering Out Dust The other important matter relating to air purity is that of filtering out dust and similar foreign matter. There are several ways of accomplishing this, one of which is with the conventional air washer. This does a very thorough job, but this type of equipment when used in connectior with other equipment essential to the conditioning of air increases the first and operating cost of the entire system rather substantially. The other method of filtering is that of using standard type filters, with which most of you are familiar. These usually have dimensions of 20x20x2 inches and are usually mounted in a frame, with a sufficient number of them to insure a low velocity of air through them. Many filters are made of spun glass fibers held in place by metal or cardboard frames. Sometimes other materials such as cardboard, hog's hair, wood shavings, etc., are used for filtering. Such filters are known as the "throwaway" type, and after they have accumulated a quantity of dust they are discarded and replaced with new ones of the same type. There are also filters of the same general characteristics which are known as the "permanent" or "cleanable" type, which are constructed of a series of layers of wire mesh or screen, each layer of which consists of mesh diminishing in size. This {Continued on page 26) 6 A Section of Motion Picture Herald