94 SKIMMING EFFICIENCY OF THE SEPARATOR 



The accompanying figures show that in the case of a cow 

 producing 6,000 pounds of milk per year and yielding 5,100 

 pounds of skim milk the loss of butter per cow per year would 

 be 12.85 pounds which at 45 cents per pound would amount to 

 $5.78. This illustration amply demonstrates that the dairy farm- 

 er cannot afford to ignore the speed of the separator and 

 should, for his own protection, use some reliable means to 

 insure the proper speed of his machine. 



It is obvious that proper attention to the speed of the 

 separator is equally necessary in the factory, particularly when 

 steam turbine separators are used. Especially in small plants 

 with small boiler capacity, the steam pressure is prone to vary 

 and this in turn causes the turbine separator to run irregularly. 

 Excessive speed due to high steam pressure is usually guarded 

 against by the installation of a blow-off valve. In the case 

 of belt-driven machines, the speed is usually more uniform, 

 provided that the engine is equipped with an efficient gov- 

 ernor, is running at a uniform stroke and the slipping of belts 

 is avoided. 



Effect of Rate of Inflow on Skimming Efficiency of the 

 Separator. The rate of inflow has a very marked influence on 

 the completeness of the separation. The capacity rated by the 

 manufacturer of the machine is supposed to represent the 

 maximum amount of milk which will insure complete separa- 

 tion. If the rate of inflow is forced beyond the specified capa- 

 city of the separator, the skin^ming efficiency decreases. This 

 is due to the fact that the milk passes through the separator 

 so rapidly that it is not exposed to the centrifugal force long 

 enough to undergo complete separation. 



A reduction below capacity of the amount of milk passing 

 through the separator is of no special advantage; it fails to 

 appreciably increase the skimming efficiency and it prolongs 

 the process of separation. These facts were experimentally 

 demonstrated by the Purdue Agricultural Experiment Station, 1 

 as shown in the following table. 



1 Hunziker. The Hand Separator and the Gravity Systems of Creaming. 

 Purdue Bulletin No ? 116, 1906. r 



