THE SPRAY PROCESS 311 



and escapes through the small orifice in the cap, forming a 

 fine spray or mist. 



The small orifice through which the milk spray enters the 

 desiccating chamber increases in size by usage due to wear, and 

 necessitates the frequent replacing of the old caps or nozzles by 

 new ones. When in operation, these spray nozzles at times be- 

 come clogged and must be changed for cleaning. It is necessary, 

 therefore, for the operator to supervise the process continually, 

 making sure that all the spray nozzles function properly, so as to 

 secure maximum efficiency and speed of desiccation. 



In order to facilitate the changing of spray nozzles while desic- 

 cation is in progress, the nozzles are so placed as to connect with 

 the milk pipe on the outside of the desiccating chamber, the nipples 

 carrying the spray nozzles connecting with the milk supply pipe by 

 means of Barco joints (loose joints), can be turned in all directions 

 sufficiently to withdraw the nozzles from the desiccating chamber 

 independently and at any time during the desiccating operation. 



Spray Pumps. In order to maintain a uniform efficiency of 

 desiccation and to secure a uniform fineness of spray, it is im- 

 portant that the pressure of the milk should be uniform. To ac- 

 complish this requires a special type of pump. The pumps best 



Fig-. 107. Hig-li pressure pump for spraying 1 milk 

 Courtesy of Union Steam Pump Co. 



suited for this purpose are three cylinder pumps with large, heavy 

 valves and with extra deep stuffing boxes that can be packed with 

 one-half inch packing rings, and special, heavily bolted glands that 

 can be readily adjusted when the pump is running. 



The triple cylinder arrangement insures a steady pressure 



