SWEETENED CONDENSED Miuc CONDENSING 71 



be above the cistern. At the sea level, the atmospheric pressure sus- 

 tains a water column about thirty-four feet high. This water column 

 in the discharge pipe seals the vacuum and at the same time permits 

 the water from the .spray and the condensation water to escape auto- 

 matically. The cistern in which the water column terminates should 

 be of sufficient size to hold about one-third more water than the ca- 

 pacity of the entire length of the discharge pipe calls for and should 

 have a large overflow into the sewer. When the pan is in operation 

 and a uniform vacuum is maintained, the level of the water column 

 remains constant and the excess water from the condenser over- 

 flows from the cistern into the sewer. 



Fig. 22. The wet-vacuum spray 



condenser 

 Courtesy of Arthur Harris & Co. 



THE WET- VACUUM SPRAY CONDENSER consists of a huge hol- 

 low cylinder of brass or iron, usually, but not necessarily, horizontal. 



The horizontal spray condensers are usually equipped with a 

 perforated spray pipe, placed lengthwise in the cylinder. This spray 

 pipe should run close to the top side of the cylinder, so as to give 

 the spray that escapes from the holes on the upper side of the spray 

 pipe a chance to strike the top of the horizontal cylinder with force 

 and to become atomized. The spray pipe connects at the end nearest 

 the pan with the pipe supplying the cooling water. When the pan 

 is in operation, a shower of cold water issues forth from the per- 

 forations of the spray pipe as the result of the reduced pressure in 

 pan and condenser. The force with which the water escapes these 

 perforations is further augmented by the fact that in most cases 

 the water supply tank is located higher than the condenser. The 

 hot vapors arising from the boiling milk in the pan are drawn over 

 into the condenser, where they come in contact with the cold water 

 spray and are condensed. The bottom of the condenser cylinder, 

 at the end farthest from the pan is connected with the suction end 



