24 CIRCULAR 740, U. S. DEPARTMENT OF AGRICULTURE 



the room to stimulate air movement will tend to make the temper- 

 atures more uniform. Fans installed to give a positive air move- 

 ment will give even better results. Fans blowing directly over the 

 cooling pipes are effective in reducing both condensation and the 

 danger of localized freezing of the fruit. 



BRINE-PIPE SYSTEM 



To avoid all possibility of accidental leakage of ammonia from 

 the cooling system into the storage rooms the cooling pipes are 

 sometimes designed for carrying cold brine. The brine is cooled in 



Figure 4. — Cold-storage room piped for direct-expansion system, with gutters 

 suspended beneath pipes over the space to be occupied by fruit. 



a separate brine cooler and circulated by pumps to the various rooms. 

 Other advantages of this method are that temperature control is 

 simpler than in a direct-expansion system and a reserve of refriger- 

 ation is available in the cold brine to carry over short periods of shut- 

 down. This system however, is more costly than direct expansion 

 and for this reason it is not commonly used in fruit districts. In 

 comparison with an air-circulation system, brine pipes otherwise have 

 the same advantages and disadvantages as a direct-expansion sys- 

 tem. A brine of calcium chloride instead of common salt (sodium 

 chloride) may be used for this type of installation. Data on the 

 density and freezing points of sodium chloride and calcium chloride 

 brines are given in table 4. 



