Structure of Centrifugal Separator 179 
cream without stopping the machine, thus making 
the separation continuous. 
This constituted the first practical cream separator. 
It was the invention of Dr. Gustaf de Laval. a 
Swedish inventor. 
The various parts 
of the machine have 
since been much 
improved in minor 
details. At the pres- 
ent time the essen- 
tial parts of a sepa- 
rator are the bowl, 
with or without 
internal devices or 
arrangements to as- y 
sist in the separa- & sa EMM 
tion of the eream Fig. 21. Dr. Gustaf de Laval, inventor of the 
from the milk, an first practical centrifugal cream separator 
outlet for the skimmed milk, an outlet for the cream, 
an inflow for the whole milk, and the proper mechani- 
cal means for revolving the bowl. (The more com- 
mon types of separator bowls are shown in Figs. 
10-13.) Usually the bowl is driven in an upright 
position, but there are separators in which the bowl 
is driven in a horizontal position, and in the greater 
number of machines the walls of the bowl are cylin- 
drical. In the process of separation the milk flows 
into the bowl, and, partaking of the centrifugal force, 
is forced to the extreme outer edge of the bowl. 
As the milk continues to flow in, the bowl begins 
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