Chapter 19. -REFRIGERATION AND AIR CONDITIONING PLANTS 



CARTRIDGE 



DEHYDRANT 



DISPERSION TUBE 



END CAP 



COVER PLATE 



FITTING SEAL PLUG 



SHELL 



47.97 



Figure 19-9.— Refrigerant Dehydrator. 



The comfort and efficiency of the crew is 

 not the only immediate reason for shipboard 

 air conditioning. Mechanical cooling, heating, 

 or ventilating must be provided for a number 

 of spaces for a variety of reasons. Ammunition 

 spaces must be kept below a certain tempera- 

 ture in order to prevent deterioration of the 

 ammunition; gas storage spaces must be kept 

 cool in order to prevent the buildup of exces- 

 sive pressures in containers; electrical and 

 electronic equipment must be maintained at 

 certain temperatures, with controlled humidity, 

 in air that is relatively free of dust and dirt. 



PRINCIPLES OF AIR CONDITIONING 



To achieve the objectives of air condition- 

 ing, it is necessary to take account of a number 

 of factors. The principal factors that are 



important in connection with air conditioning 

 are discussed in the following sections. 



HUMIDITY.— The vapor content of the at- 

 mosphere is referred to as humidity. Excessive 

 humidity and too little humidity both lead to 

 discomfort and impaired efficiency; hence the 

 measurement and control of the moisture con- 

 tent of the air is an important phase of air 

 conditioning. 



The air holds varying amounts of water 

 vapor, depending upon the temperature of the 

 air; the higher the temperature, the greater 

 the amount of moisture the air can hold. For 

 every temperature there is a definite limit as 

 to the amount of moisture the air is capable of 

 holding. When air attains the maximum amount 

 of moisture which it can hold at a specified 

 temperature, the air is said to be saturated. 



483 



