68 SWEETENED CONDENSED M1LK—CONDENSING 
CHAPTER V. 
CONDENSING. 
From the ground well in the well room the sweetened milk 
is drawn into the vacuum pan, where it is condensed under 
reduced pressure. ‘The vacuum pan is usually located on the 
second floor over the well room, or in the well itself, in which 
case it is elevated above the floor six to eight feet. The vacuum 
pan is connected with the vacuum pump, which should be in- 
stalled near the pan. 
Description of the Vacuum Pan. 
—The vacuum pan is a retort in 
which the milk is heated and evapo- 
rated in partial vacuum. The origin 
of the term “pan” has not been 
satisfactorily explained. In the early 
and experimental days of the manu- 
facture of condensed milk, the milk 
was evaporated in open _ kettles, 
called pans. It is probable that the 
name of this primitive apparatus 
was passed on to the more perfected 
machinery now in use. 
The vacuum pans are construct- 
ed of copper, iron, steel or bronze 
Practically all of the vacuum pans 
Fig. 15. used for condensing milk are made 
Vacuum pai ‘and’ condenser of copper throughout; they are of 
Courtesy of Groen Mfg. Co, Various styles and sizes. The pre- 
dominating size used in milk con- 
denseries is the ‘six-foot pan.”” By the term six-foot is meant a 
retort measuring six feet in diameter. 
There are two general types of vacuum pans on the market; 
pans that are relatively wide in diameter and shallow in depth, 
and pans of relatively narrow diameter and which have a deep 
body. Both types are claimed, by their respective manufacturers, 
to have special advantages, such as ease of operation, uniformity 
of action, economy of fuel and of water, and rapidity of evapora- 
