THE PASTEURIZATION OF MILK 



Again, it can be seen that if the temperature of 

 the milk as it enters the tank from the heater is 

 not accurately controlled, it will frequently occur 

 that the temperature will drop, and this cooler milk 

 will fall through the body of milk toward the bot- 

 tom. It is also true that the force of the milk as 

 it enters the tank from the heater will, unless this 

 force is broken, tend to carry the milk deeply into 

 the body of that already in the tank, and so cre- 

 ate currents which will interfere with the actual 

 holding time. This force is broken by placing 

 some sort of a baffle plate under the inlet pipe. 

 This baffle is sometimes so arranged that it floats 

 on the surface of the milk, and rises as the tank 

 becomes filled. In other cases a flat piece of 

 metal is placed near the top of the tank, and may 

 or may not contain perforations which allow the 

 milk to flow through as well as over the edge of 

 the plate. It is immaterial what form of spreader 

 is used so long as the currents are broken up. It 

 will be seen by referring to the illustration that 

 the inverted U-shaped pipe for the discharge of 

 the milk is provided with a by-pass valve, so that 

 the tank can be emptied when the operation is 

 completed for the day. It is important that this 

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