SKIMMING EFFICIENCY OF THE: SEPARATOR 101 



collects in the separator bowl, forming the so-called separator 

 slime. It is deposited largely on the walls of the bowl and 

 between the internal contrivances. 



This slime also impedes the free passage of the milk and 

 cream within the bowl, thereby reducing the diameter, centrifugal 

 force and capacity of the bowl, lowering its skimming efficiency 

 and causing excessive loss of fat. This loss is greatest with milk 

 in poor physical condition. The results of experiments 1 with 

 clean and unclean separators are shown in Table 10. 



Guthrie 2 found that, within reasonable limits, deposits of 

 separator slime in the bowl do not materially interfere with the 

 skimming efficiency of the machine. He concludes that only 

 when the bowl fills up with separator slime to the extent of 

 clogging the passages, does the efficiency of separation suffer. 



In his tests, Guthrie used from 240 to 320 pounds of milk 

 only per test. He does not state the rated capacity of the sepa- 

 rator. It is probable, therefore, that in these experiments the 

 amount of milk used was too small and the amount of sepa- 

 rator slime centrifuged out too limited to materially affect the 

 diameter of the bowl and the centrifugal force. 



In commercial separation of the milk, where the separator 

 often is in continuous operation for several hours, the accumu- 

 lation of separator slime is frequently very great and this in 

 turn is bound to seriously diminish the skimming efficiency 

 of the machine. 



Effect of Condition of Milk on Skimming Efficiency of the 

 Separator. Milk in poor mechanical and physical condition, 

 such as milk containing a relatively large amount of impurities, 

 or milk, which is old and partly sour or curdy, tends to lower 

 the skimming efficiency, largely because it augments the am- 

 ount of separator slime which collects in the bowl; this in turn 

 impedes the free passage of milk and cream and causes exces- 

 sive loss of fat. 



If the milk is curdy the danger of incomplete separation 

 is augmented by the fact that each particle of curd locks up a 

 small amount of fat, and the curd passing into the skim milk 



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

 Purdue Bulletin No. 116, 1906. 



2 Guthrie. Variations in the Tests for Fat in Cream and Skimmed Milk. 

 Cornell Bulletin No. 360, 1915. 



