DAIRYING 61 



Position of the Cream Screw and of Skim Milk Tubes in the Bowl. 



338. When the cream screw is turned in, a richer cream is 

 obtained because it takes cream from nearer the center of the bowl. 

 Turning the screw out will naturally make the cream thinner. 

 A fraction of one turn of the screw is often sufficient to make a 

 difference of several per cent, in fat in the cream. 



When adjustable skim milk tubes are placed in the bottom 

 of the bowl these should be turned out to make the cream richer, 

 as this will force more skim milk through them. 



Variations in Speed. 



339. The amount of skim milk thrown out the skim milk 

 tubes may be increased by increasing the speed of the bowl, and 

 this will naturally make less and richer cream. Reducing the 

 speed gives opposite results and makes a thinner cream. 



If the cream coming from a separator is getting thin this may 

 be due, first, to clogging of the bowl with slime so that the skim 

 milk cannot pass through the skim milk tubes of the bowl ; second, 

 to a reduced speed; third, to too much milk flowing into the sepa- 

 rator; fourth, to a change in the cream screw. 



340. One of the most common causes of a variation in the 

 richness of cream from the farm separator is the different amount 

 of water or skim milk that is used to flush out the bowl when 

 through skimming. Most of this goes into the cream spout and 

 the extent to which the cream is diluted by it will depend on the 



imount of rinsing water used. 



Uniformity in all the operating processes will help to give a 

 :ream of uniform richness. 



341. The following figures show the effect of various condi- 

 tions of operation on the richness of separator cream, most of the 

 igures being taken from Kan. Exp. Sta. Bui. 137: 



Influence of Temperature of Milk. 



. of milk, F. deg. . 115 110 90 80 70 



:ream test, fat % 32 30 29.5 29 27 



)kim milk test, fat % . . .01 .01 .012 .02 .039 



