THE PASTEURIZATION OF MILK 



pipe at the bottom of the series, and operates 

 valves which automatically regulate the discharge 

 of the milk. 



There is one thing which should be carefully ob- 

 served regarding this form of holder. It will be 

 noted that the two shafts which operate both the 

 inlet valves and the outlet valves are impelled by 

 a single worm-driven gear. Thus both shafts 

 move in unison. Care must be taken to make sure 

 that no inlet valve is opened into any tank till the 

 outlet valve is completely closed, otherwise some 

 milk will flow out without being held for the 

 proper length of time. 



In calculating the holding time with this appa- 

 ratus, it must be noted that since there are but 

 seven tanks in the series, there is required one- 

 seventh of the entire period of sequence for each 

 tank to fill and one-seventh for it to be emptied. 

 Thus the entire time of sequence must be reduced 

 by two-sevenths. A little thought will make it 

 clear that as the number of tanks in a series de- 

 creases in number, the time of revolution or se- 

 quence must be increased. With eight tanks a 

 period of revolution of forty minutes reduced by 

 25 per cent, would equal thirty minutes. If, how- 

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