COLD STORAGE FOR APPLES AND PEARS 



33 



insulation, which slows the passage of heat by resisting its flow. The 

 resistance depends upon the character of the insulating material and 

 its thickness. A comparison of the effectiveness of various insulating 

 materials can be made by showing thicknesses that will pass equal 

 quantities of heat under similar conditions. 



In many apple and pear cold storages 12 inches of shavings is used 

 for insulating the walls. The thickness of various other materials 

 required to equal the resistance of 12 inches of shavings is shown in 



Figuee 9. — A small opening, or port, for use in receiving or shipping small pack- 

 ages of fruit (A) over a conveyor without keeping the larger doors open. The 

 small opening should be covered with a flap of heavy canvas (B) to prevent loss 

 of cold air when a package is not passing through the opening. When it is 

 necessary to use a large doorway for trucking, the heavy insulated door ( at left, 

 not shown) stands open. The light metal-clad doors shown may be bumped 

 open with the truck and will swing closed after each truck has passed, thus 

 saving much refrigeration that would otherwise be lost through the open 

 doorway. 



table 6. When more than one material appears in the cross section of 

 a wall the total insulating value of the wall is the sum of the values 

 for each of the parts. 



Frequently in constructing storages air spaces are provided between 

 the various sections of the wall. These tend to hinder the flow of 

 heat, Unless reflecting surfaces are used to line the spaces, however, 

 it would take three to four spaces each at least % inch thick to 



669297°— 46 5 



