COLD STORAGE FOR APPLES AND PEARS 59 



and water from defrosting may be a problem in direct-expansion plants, 

 but removal of the frost during the cooling period is important. 



BRINE TREATMENT 



In brine-spray plants the frost is washed off with brine, which is con- 

 tinually being diluted by the condensed water, making it necessary to 

 drain off some at intervals and add more salt. The brine should not be 

 any stronger than necessary to prevent accumulation of ice. One ob- 

 jection to brine-spray systems is that upon exposure to air the brine 

 tends to become acid. Unless this tendency is checked the particles 

 of brine carried by the air are very corrosive and may damage any 

 metal with which they come in contact. The brine may be treated with 

 a chemical to retard this corrosive effect. The instructions regarding 

 such treatment, which are furnished by the company installing the 

 equipment, should be followed carefully. Such instructions should be 

 requested if they have been lost or forgotten. 



CARE OF CONDENSER 



The water used in condensers leaves on the pipes a deposit that, if 

 allowed to accumulate, interferes with heat transfer. The water tubes 

 of a condenser should be examined at least once each year, preferably 

 prior to the harvest season, to make sure they are in good condition, 

 and if necessary they should be given a thorough cleaning. 



CARE OF COMPRESSOR 



The compressor and other machines, including motors and pumps, 

 need careful attention. Instructions furnished by the machinery manu- 

 facturers should cover operation of the particular machines in the plant 

 and should be kept in the engine room and referred to frequently. 

 Carelessness in operation or failure to observe the recommended rou- 

 tine may prove expensive in repairs. 



CONTROLS 



Automatic parts of the numerous types of control equipment used in 

 various plants usually depend upon changes in temperature or pressure 

 or are controlled by clocks. It will pay to become familiar with the 

 principle of operation of each item involved in automatic control. 



CARE OF FANS 



In air-circulation systems fan size and speed are usually selected to 

 deliver a certain volume of air against an estimated resistance. If the 

 resistance is kept as low as possible, a maximum volume of air will be 

 circulated. Frequently a fan will be found to have a film of dirt and 

 grease accumulated on the blades and in the interior. This interferes 

 with air flow and should be cleaned off. 



DUCTS AND DAMPERS 



The dampers and openings in ducts should be set open wide enough 

 to permit the desired air distribution. In making adjustments the 



