STORAGE OF FRUITS, VEGETABLES, AND FLORISTS' STOCKS 3 



and represent the average air temperatures that should be maintained. 

 The humidities are relative and are expressed in percentage of satura- 

 tion ; for example, when it is stated that a certain humidity should be 

 85 percent, this means that the air should be at approximately 85 per- 

 cent of complete saturation with water vapor at the recommended 

 temperature. Allowance has been made for the facts that the tem- 

 perature of fruits and vegetables in transit is usually higher than 

 the recommended storage temperature and that, except during winter 

 weather, ripening or other changes are likely to go on more rapidly 

 during a given transit period than during the same length of time 

 in cold storage. 



Temperature of Storage Rooms 



If the best results are to be obtained in the cold storage of the prod- 

 ucts discussed herein, it is highly important that the temperature in 

 storage rooms be held fairly constant. Variations of 2° or 3° F. 

 above or below the desired temperature are in most cases too large. 

 They can usually be avoided if the storage rooms are well insulated 

 throughout and have adequate coil surface and if the spread be- 

 tween the temperature of the refrigerant and that of the room to be 

 refrigerated is kept small. For example, in a room where 45° is 

 the desired temperature, using ammonia evaporating at about 26° 

 in the coils, fluctuations of ^l 1 /^ m &y occur in the air temperature 

 in the room; whereas at 32°, with ammonia also at 26°, fluctuations 

 in the room temperature are usually less than ±V2°- However, 

 the spread between the temperature of the refrigerant and that of 

 the room is more important in maintaining humidity than in pre- 

 venting fluctuations in the room temperature. This point is dis- 

 cussed in more detail on page 4. Storage rooms should be equipped 

 either with reliable, accurate thermostats or with means for manual 

 control which are given frequent personal attention by someone 

 charged with that duty. Even when reliable automatic controls are 

 used, they should be checked periodically by some responsible 

 person. 



In commercial cold-storage rooms thermometers are usually 

 placed at a height of about 5 feet, sometimes slightly lower, for con- 

 venience in reading. It is important, however, to take temperatures 

 frequently at the floor and the ceiling also, and at any other places 

 where they might be expected to be undesirably high or low. In 

 providing recommended temperatures for given products, considera- 

 tion should be given to differences between the temperatures of the 

 air at the position of the thermometer and at different places around 

 the packages of the stored product, and also to differences between 

 air and commodity temperatures. Often the packages are piled too 

 closely together, or distribution of refrigeration is inadequate to 

 reach all parts of the piles of the stored commodity, and it is not 

 unusual under such conditions to have commodities remain for sev- 

 eral days or even weeks at temperatures several degrees higher than 

 those indicated by the thermometer. This condition can be detected 

 by opening the pile and taking commodity temperatures and can be 

 corrected by wider spacing of packages and the use of portable 

 fans and baffles for the direction of air currents to the centers of 



