FROM THE PRACTICAL VIEWPOINT 



Second. We should be sure that every particle 

 of milk is held for the minimum time required. 



Third. The valves for admitting and releasing 

 the milk must be so tightly fitted that no milk 

 can by any possibility be discharged before the 

 proper holding time is completed. It may be pos- 

 sible for valves to become so worn by use that 

 annular grooves will be worn around them, thus 

 allowing milk to be by-passed while the valve is 

 closed. 



Fourth. Make proper calculation to determine 

 that the cycle of filling, holding and emptying of 

 the tanks is long enough to make sure that the hold- 

 ing time is sufficient and in addition to allow for 

 the filling and emptying of the tanks. 



Fifth. Make sure that the inlet valve is never 

 open into a tank before the outlet pipe is closed. 



Sixth. Since the ease and convenience of clean- 

 ing is an item of importance, as a general propo- 

 sition it may be said that, other things being equal, 

 a machine which has the fewest pipes and valves 

 consistent with efficient operation is the most de- 

 sirable. 



Seventh. It is desirable that as little foam as 

 possible be produced in the operation of a holder. 

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