CONDITIOXS AFFECTIXG EFFICIENCY OF SEPARATORS 165 



diameter of the Ijowl; that is, if the diameter of tlie Ijmvl Ije 

 doubled, then at the same speed, the eeiitrifuL;:al force has been 

 doublefb The centrifugal force A-aries in quadratic proportion 

 to the si:)eed of the machine; that is, if the speed of the se])arator 

 is doul)led, the centrifugal force is increased four times. From 

 this it will be seen that speed is a, great factor in determining the 

 centrifugal force generated. It is not a good jjlan to ha\'e the 

 diameter ol the bowl too large, for the following reasons: A large 

 bowl is more likely to he thrown out of Vjalance; it is harder to 

 keep on the bearings; and it is heavier and more unhand}' to 

 handle. For these reasons it is better to lessen the diameter of 

 the bowl and increase the speed. This, of course, is true only to a 

 certain limit. 



Steadiness in Running. — Smooth running of a separator is 

 one of the lirst essentials. If a machine runs roughly, there will 

 not be good separation, and it is dangerous to run it. The 

 bowl itself is likely to jump out, or burst. The causes for 

 unsteadiness in running are man}-. It may be due to a bent or 

 si:irung spindle; the machine not standing level ; changing covers 

 to bowls; using clamps which do not lit the bowl co\'er; unclean, 

 worn-out bearings; condition of the bowl, and contri\-ances 

 inside the Ijowl; and dented and rusty bowls. OceasionalU' it 

 happens that a machine is run backwards. This is likeh' to 

 cause the cover of the bowl to run off. 



Thickness of Cream. — The efficiency of skinmdng depends 

 to some extent upon the thickness of the cream skimmed. Most 

 separators, however, will skim within quite a wide range as to 

 thickness. The richness of cream usually skunnied In* separators 

 ranges from 25 per cent to 50 per cent. ?tIost separators, how- 

 ever, will do good skimming even if the cream contains as hig:h 

 as 60 per cent fat. This, however, should be considered to be 

 about the maximum, in order to get the best results from a sep- 

 arator. 



Slush in Bowl. — As has been mentioned before, there is 

 always a thick, slimA" substance which adheres to the bowl-wall. 

 The composition of separator-slime is, according to Fleischmann, 

 as follows: 



