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1950-51 Theatre Catalog, 9th Edition, Page 375 (353)

1950-51 Theatre Catalog, 9th Edition
1950-51 Theatre Catalog
1950-51 Theatre Catalog, 9th Edition, Page 375
Page 375

1950-51 Theatre Catalog, 9th Edition, Page 375

Maintenance of the Air Conditioning Plant

Practical Tips on Good Housekeeping for TroubleFree Operation and Maximum Equipment Life

Basically speaking, every cooling plant comprises two main cyclesethe air cycle and the refrigerant cycle. Since identical maintenance suggestions are applicabl to all ventilating systems, with or without refrigerants, the air cycle will be discussed tirst. This cycle is simply a duct system delivering cleaned air pumped by a fan to those localities to be cooled.

The fan is usually set up to pull fresh air in from the outside through a set of filters, which remove dust and soot; to push the air over the cooling coils, where it is lowered in temperature and moisture removed (dehumidification); and to propel it through the duct system into the auditorium, lobby, lounges and other theatre rooms.

In a majority of systems there are also return air ducts, which permit the re-use of some or all of the previously cooled air. On days when Old Sol is throwing down a barrage of heat, some savings can be effected by closing the fresh-air intake and re-circulating the inside air until the interior is cooled to the desired temperature. But, it must be borne in mind that, in order to dispel sweaty odors, and return oxygen to the used air, some fresh air must always be on its way into the occupied house.

Care of the Fun

Particularly important is the care of the fanethe most vital part of the air cycle. Periodically the blades should be scraped with a wire brush, removing rust and other surface soil. Then, for

CASE HISTORY: A theatre manager called up a theatre maintenance engineer and began grumbling about an exhaust fan in his house. For the life of him, he couldnit figure out why the darn thing didnit blow out more air. He had fiddled and tinhered around, looking for stoppages in the lourres and duct work, but, even after this assault, he was still up a blind alley. Bitter and frustrated, he requested the engineer to speed up the fan and said that he would rather be responsible for the price of a new motor#and pulley and belts; than be necdled by his present limpid setup.

When the theatre maintenance engineer made his examination he found that there were no stoppages, Further detective work uncovered the startling et'idence that the fan was runnng backwards and had been on this binge for the past eight months.l That Ion/1 ago the motor had been overhauled and two leads in the motor switchbox had gotten mixed up, liy interchanging these. the engineer soon had the fun running in the right direction and properly ventilating the house.


BRIEF: In this highly technological day and age, the specialist in repair . . . who understands and can fix . . . the intricate machines which the advance of civilization has brought in. its wake . . . is w revered iifair-haired boyi, indeed . . . He is often so busy . . . tracking down faults in mechanical units . . . that it may be almost impossible for him to answer all calls that come his way . . . Oftentimes the cries for help he receives would not be necessary . . . if the trouble prompting them had been prevented by the use of a little common iihorse sensei, beforehand . . . on the part of the caller . . .

Theatre air conditioning systems . . . for example . . . generally stand up well under all kinds of stresses . . . if given proper attention. A few simple maintenance procedures . . . as outlined in this article . . . will keep a cooling system in. first-class shape . . . and do away with the necessity for a good many calls to the beleaguered repair man.


durable painttadhesion, the metal should be treated with a phosphoric acid metal cleaner, and then painted with red lead or zinc chromate before the application of the final heavy protective coat of paint. This identical treatment should be given the fan casings and any other metal parts of the system. In addition, bearings should be kept clean and lubricated with a dirt-free oil or grease, as specified by the manufacturer.

The main obstacles to good operation of the fan are corrosion, wear, and poor lubrication. Regular inspection should be made of the fan assembly, and evidence of damage from corrosion or vibration looked for carefully at this time. Lubrication should also be checked at every inspection. The motor should also be checked at frequent intervals in a search for signs of trouble.


Most fans are belt-driven. In order to prevent their rapid deterioration, the belts must be kept taut and absolutely free of grease and oil. Loose belts are taken up by sliding the motor to a point where no more than one-half inch of play is discernible when it is pressed by a finger.

A handy rule of thumb to remember when tightening a V-bclt is that a slack belt will feel dead to a hand thump and that a correctly tensioncd bclt will feel springy and lively. In plants where multi-bclts are used, some belt manufacturers suggest that the position of the belts be rotated to insure longer life.

Caro, however, must be taken when removing or installing belts to make certain that they are not too taut. Undue strain will break the outside strands.

All belts are supplied with the manufacturers name and belt size printed on them, usually in the form of code numbers. This data should be filed away to facilitate replacements.

CASE HISTORY: Late one sultry Saturday afternoon, the telephone jangled, and at the complaining end was another distraught theatre manager. He was so excited that he could scarcely relate the fact that a set of belts used to run an air-conditioning compressor had become overheated and burst into flames. In a short time, the theatre maintenance engineer was on the spot with knowledge, experience, tools and aspirins,

Things could have been worse. The compressor room was well-aired; no smoke had seeped into the public sections of the house. And nobody, with the noticeable exceptionof the manager, was in a panic. Here was the situation. The belts, of wartime vintage, had been allowed to become loose. Results ant friction from, slippage had set them on fire. A set of spare belts in the engineerls kit soon remedied the defect and the air was cleared and freshened in a matter of minutes.

Air Ducts

It is extremely important that air ducts be checked periodically for loose connections and loose insulation. Access holes should be put into the ducts fore the periodic removal of dust. This last, more than being merely good housekeeping, eliminates a very serious tire hazard. And last, but not least, fire dampers should be looked into similarly for proper closings.

CASE HISTORY: In a theatre in South Philadelphia, a sudden rash of Hichcring spots on the screen et'ohed visions of fire in the minds of some 20 of the 200 members of the cinema audience. They promptly tumbled out of the nearest exits. One of the safety-minded customers telephoned the Fire Bureau: and a few moments later two fire companies shriehcd to a stop outside. Finding the show going on as usual, thedisappointed firemen wanted to know what the fuss was all about.

By a grotesque coincidence, turning on the air-conditioning system for the season created clouds of dust, which, when reflected on the screen, mode the place look highly combustible, the manager told them. Here, dust, had become a potential instigator of panic.

1950-51 Theatre Catalog, 9th Edition, Page 375