> > > >

1947-48 Theatre Catalog, 6th Edition, Page 415 (401)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 415
Page 415

1947-48 Theatre Catalog, 6th Edition, Page 415

The Control of Humidity in Comfort Cooling

Adiustment of Amount of Water in the Air

Essential to Make Comfortable Conditions


Surface Combustion Corporation

Whether the air in an air-conditioned building is comfortable or not depends primarily on two basic factorswtemperature and humidity. The air cannot be made comfortable unless both are maintained in their proper relationship.


Persons indoors in the summertime can be very uncomfortable at a temperature of 7.3 degrees Fahrenheit, if the humidity is too high. Even though the temperature would otherwise be within the comfort range, if the humidity is not in proper relationship with it, the result is often a chilly claminess which

is not only very uncomfortable but unhealthy.

When the humidity in a summer airconditioned space is properly controlled, it is not necessary to lower its temperature as much to make it comfortable, as it is when the humidity is too high. It has been found in actual practice, for instance, that 82 degrees Fahrenheit and 40 percent relative humidity in a conditioned space is far more comfortable, healthful, and free from shock than a space held at 75 degrees Fahrenheit with 65 percent relative humidity. The complaints which we have experienced from air-conditioning can be corrected by assuring proper control of humidity first. Then the problem of temperature control becomes comparatively simple.


The best criterion for comfort in an air-conditioned space is that persons present are not conscious of the atmosphere or of any artificial change in it. In order to accomplish this condition, it is necessary to control temperature and

SCHEMATIC DIAGRAM of how the Kathabar system operates, shows the

, l


HYGROTHERMOGRAPH RECORDS show how steady both temperature and humidity can be controlled (left). When only temperature is controlled (right), the humidity of the test space follows a pattern comparable to that found out of doors (where the humidity. however, frequently reaches saturation). With such diurnal fluctuations in humidity, the maintenance of true comfort conditions is difficult.

humidity in their proper relationship and also eliminate odors, get the correct air circulation with sui'Hcient cleanliness. The most comfortable atmosphere you have ever experienced, perhaps in your favored vacation retreat, will live up to all of these specifications.

On the basis of specifications just outlined, it is easy to see why so many air-conditioned spaces fall short of true comfort. If all of the requirements except odor removal, for instance, are properly taken care of air-conditioned space will still be uncomfortable.

The problem of adequately controlling

This discussion of the Kathabar System of humidity control is reprinted by special permission of F. M. Johnson from the brochure, thontrol Humidity If You Want Comfort From Air Conditioningf published by the Surface Combustion Corporation.

temperature and humidity is still further complicated by the fact that both these factors in outdoor air vary over a wide range. A drop in temperature, for instance, may be accompanied by a rise in humidity and vice versa, so that equipment selected for one given ratio at one time may be entirely inadequate when this ratio suddenly changes. The only logical procedure, therefore, is to control temperature and humidity independently. The problem is reduced to its simplest form when humidity is controlled first ethen temperature.


The laWs of physics provide just two alternatives to the dehumidification of atmospheric air: (1) The air may be cooled sufficiently below the dew point or Hsaturation pointti to condense or squeeze the moisture out of it, and then it may be reheated to the required temperature, and (2) moisture may be taken out of the air by chemical means, in which case, the temperature need not be changed.

This latter method of removing the humidity to any desired point without

(arrow 2) the air at the proper humidity passes over heating (or cooling)

air entering at the left and immediately passing through an air filter. The coils. Properly adjusted as to both temperature and humidity (arrow 3)

filtered air (arrow 1) passes into the contactor, - i I (in winter service) or dehumidified (in summer servrce). From "115 point


CO For H and De


where it is humidified

the air passes to the fans and into the circulation system (arrow 4). Thus is true conditioned air delivered for the comfort of the patrons.

iii ll

K4. //

HEng //// /

til ll.


Os \
1947-48 Theatre Catalog, 6th Edition, Page 415