SWEETENED CONDENSED MILK CONDENSING 65 



The body or vapor belt 

 represents the main part of the 

 pan. It is cylindrical, of vary- 

 ing height and is equipped with 

 copper coils which have their 

 outlets through the jacket. Their 

 upper ends connect, through the 

 body of the pan, with the main 

 steam line. Most pans are 

 equipped with two to three coils 

 located at different elevations. 

 Since steam should be turned 

 into the coils only when they 

 are covered with the milk, it is 

 desirable to have several short 

 independent coils rather than but 

 one large one. This will give a 

 larger range of the quantity of 

 milk that can be condensed and Fig> 14 ' Vacuum pan and condenser 



Courtesy of C. E. Rogers 



increases the speed of evapora- 

 tion. The t coils -vary in diameter from about three to five inches. 

 The upper and outer coils are the larger ones. The diameter and 

 length of the coils necessarily vary with and are limited by the 

 capacity of the pan. The greater the total heating surface, consistent 

 with easy access to all parts of the jacket and coils, the better. 

 Other things being equal, the more square feet of heating surface, 

 the less steam pressure, by the gauge, is required to furnish the 

 necessary heat for maximum evaporation. This is important 

 because high steam pressure in the jacket and coils means exposure 

 of the milk to high temperature, which is undesirable. The heating 

 surface should be sufficient to make possible the complete con- 

 densation of the steam in the jacket and coils. If the heating 

 surface is inadequate, more steam has to be turned into the jacket 

 and coils, in order to secure the necessary heat for rapid evapora- 



