78 SWEETENED CONDENSED MILK CONDENSING 



feet above the water level of the cistern in which the discharge 

 pipe from the condenser terminates. The height of the condenser 

 depends on the barometric pressure of the location where it is 

 installed. The lower the altitude and, therefore, the higher the 

 atmospheric pressure, the higher must the condenser be above 

 the cistern. At the sea level, the atmospheric pressure sustains 

 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 automatically. The cistern in which the water column 

 terminates should be of sufficient size to hold about one-third 

 more water than the capacity 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 main- 

 tained, the level of the water column remains constant and the 

 excess water from the condenser overflows from the cistern into 

 the sewer. 



The Wet-Vacuum Spray 

 Condenser consists of a huge 

 hollow cylinder of brass or iron, 

 usually, but not necessarily, 

 horizontal. 



The horizontal spray con- 

 densers are usually equipped pi ^ 26 - wet-vacuum horizontal 



ri ^ spray condenser 



with a perforated spray pipe, Courte sy of Arthur Harris & Co. 

 placed lengthwise in the cyl- 

 inder. 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 perforations of the 

 spray pipe as the result of the reduced pressure in pan and con- 

 denser. The force with which the water escapes these perfora- 

 tions 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 



