SWEETENED CONDENSED MILK CONDENSING 85 



temperature of the condenser discharge should be about 110 de- 

 grees F. A lower temperature would cause excessive and un- 

 economic use of water unless the available water has a temper- 

 ature lower than is the case in the average American condensery 

 (50 to 60 F.). The basin on the vacuum cylinder should be 

 kept filled with water to prevent admission of air to the cylinder 

 through the stuffing box, and the spray pipe, jet, or spray plate in 

 the condenser should be inspected often to make sure that the 

 perforations are not clogged. The stuffing box of the cylinder 

 should be well packed with a good quality of packing and the 

 steam cylinde-r well oiled. Start the pump slowly. Belt-driven 



Tig. 31. Wet-vacuum pump 



Courtesy of Union Steam Pump Co. 



pumps, especially those equipped with a fly-wheel, insure greater 

 uniformity of speed than direct-acting, steam-driven pumps. 

 Steam-driven pumps should be furnished with a high grade gov- 

 ernor. The vacuum pump should have a capacity proportionate 

 to the size of the vacuum pan, amount of heating surface, steam 

 pressure and temperature of condensing water. 



Science and Practice of Evaporating in Vacuo. 



Purpose of Condensing in Vacuo. The important advan- 

 tages gained by evaporating milk under reduced pressure, or in 

 vacuo, are : economy of evaporation, rapidity of evaporation, low 

 temperature and large capacity of apparatus. All of these features 

 are essential in the successful condensing of milk. 



