EVAPORATED MILK HOMOGENIZING 



127 



Kinds of Homogenizers. There are at this time three makes 

 of homogenizers in use in this country, namely, the "Gaulin" 

 homogenizer, the "Progress" homogenizer and the "Viscolizer." 



In the Gaulin homogenizer, the milk is forced, by means of 

 single-acting pumps, against an agate valve which presses against 

 a ground valve seat. The milk has to pass between the ground 

 surfaces of this valve and valve seat. 



In the Progress homogenizer the homogenizing principle 

 consists of forcing the milk, by means of single acting pumps, 

 between a series of discs with ground surfaces. The discs lie 



Fig-. 48. The Progress homog'enizer 

 Courtesy of Davis-Watkins Dairymen's Mfg. Co. 



Pig". 49. 



Homogenizing- discs 

 and screw 

 mechanism 



flat one upon the other, they are enclosed in a cylinder and are 

 held in place by a rod running through their center. The discs 

 are pressed against each other by a heavy spiral screw, which 

 regulates the pressure to which the milk is subjected. The milk 

 passes from the center to the periphery of the discs. The discs 

 used in this machine are of two types. One type has very fine 

 irregular grooves. The milk shoots through these grooves 

 against hard shoulders. The other type of discs has smooth 

 surfaces but their area of contact is narrow. The milk passes 

 through these smooth surfaces, 



