SWEETENED CONDENSED MILK CONDENSING 81 



In another type of vertical spray condenser the insulated 

 vapor tube in the center is surrounded by a spray chamber of 

 much greater width, and the water spray starts near the bottom 

 of the chamber from perforations in a circular coil. The per- 

 forations are so located that the spray slants upward and out- 

 ward. As it strikes the periphery of the condenser, it is deflected 

 downward and toward the center. It is claimed that in this 

 case two sheets of spray are formed, through which the vapors 

 must pass. Baffle plates extend downward and outward from the 

 top of the vapor tube preventing any of the spray from entering 

 the vapor tube. Manholes with covers are provided at the sides 

 to make possible easy cleaning of the condenser. 



Instead of the condenser being attached direct to the dome 

 of the vacuum pan, the condenser may form a part of the vacuum 

 pump. This arrangement is feasible both in the case of the wet- 

 vacuum spray condenser and in the case of the surface condenser. 



The chief difference* between the wet-vacuum condenser and 

 the barometric condenser is that in the wet-vacuum condenser 

 the water from the condenser passes through the vacuum pump, 

 while in the barometric condenser the water does not pass 

 through the vacuum pump, but goes direct into the sewer and the 

 vacuum is sealed by the barometric water column. So far as 

 practical experience has shown, there is no material difference 

 in the efficiency between these two types of condensers. The 

 \vater column of the barometric condenser helps somewhat to 

 maintain a uniform vacuum. It necessitates, however, the in- 

 stallation of the pan inconveniently high and requires somewhat 

 more expensive machinery than is the case with the wet-vacuum 

 condenser. The chief difference between both of these systems 

 and the surface condenser is that, in the wet-vacuum and baro- 

 metric condensers the condensed vapors mix with the cooling 

 water, while in the surface condenser the condensed vapors are 

 collected and carried off separately and without mixing with 

 the cooling water. In the case of condensing liquids, the vapors 

 of which are of commercial value, the surface condenser must be 

 used. The surface condenser, however, is of relatively small 

 capacity and the cooling water cannot be utilized as economically 

 as in the case of the other systems. Where large quantities of 

 vapors are to be handled and the vapors have no commercial 



