174 REFRIGERATION AND ITS USES 



The coils submerged in the brine vat are evidently cooled 

 about to the boiling point of the ammonia. But it is generally 

 the case that the brine is about 10 higher than this. More- 

 over, the brine is generally about 6 warmer when it returns 

 from the coils, H-H, than when it passes through the pump 

 on its way to the coils. Again, the air in the storage room is 

 usually about 6 warmer than the brine within the coils, H-H. 

 Altogether, then, the air in the storage room is about 22 

 above the boiling point of the ammonia. 



Now we have already seen how the boiling point of the 

 ammonia is controlled by controlling the pressure on the low 

 side of the refrigerating system. In the storing of fruits where 

 the temperature should be 36F., the boiling point of the am- 

 monia must be about 22 lower, or about 14F. By referring 

 to Fig. 125, we see that the boiling point of ammonia is 14F. 

 when under a pressure of about 44 Ib. to the sq. in. There- 

 fore, in storing such fruits, the regulating valve is so set as to 

 maintain a pressure of about 44 Ib. on the low side. 



Most kinds of fruit keep best when stored slightly above 

 32F. If it is found that the temperature of the air in 

 the store room is 22 above the boiling point of the ammonia, 

 we see that the boiling point of the ammonia would need to 

 be kept at about 10F. Referring to the curve we find that 

 the pressure of the low side should be about 40 Ib. 



In a similar manner, show that the pressure on the low side must be 

 about 33 Ib. for the storing of meat which keeps best at about 25F.; 

 at about 27 Ib. for the storing of poultry at 15F.; and that the pres- 

 sure on the low side must be about 18 Ib. for the storing of fish which 

 must be kept at zero F., if the air in the store room is 22 above the 

 boiling point of the ammonia in the low side pipes. 



203. Refrigeration and Transportation. A fruit has a 

 life history extending from the formation of the fruit bud to 

 the decay of the ripened fruit. Some fruits have short life 

 histories, others, longer. Fresh fruits, when not overripe, 

 are alive; they do not readily decay. Some fruits, such as 

 strawberries, die very soon after reaching maturity; others, 



