88 DAIRYING 



ter and all bottle fillers should be as plain and as smooth as possi 

 ble so as to make the cleaning and sterilizing of the bottle filler 

 easily accomplished. Rubber parts should be avoided because of 

 the tendency of rubber to soften and swell when exposed to' the 

 necessary sterilizing temperature. All bottle fillers should be 

 covered and the cover used when the tank is filled with milk, in 

 order to protect it from dust, flies, and other outside contamina- 

 tion. 



825. A sterilizer for heating empty bottles and all milk 

 utensils and tinware after cleaning them is absolutely necessary. 

 It is true that large, power bottle washing machines rinse the 

 bottles with hot water and this may be made efficient enough to 

 leave the bottles nearly germ-free without heating them in a 

 sterilizing oven, but such ovens are essential wherever milk is 

 handled in quantity as the milk pails, dippers, cans, and all uten- 

 sils need to be heated to a temperature up to or above that of 

 boiling water in order to destroy the germs that sour the milk 

 and the disease germs that grow so easily in milk. 



Sterilizing ovens can be bought of any desired size. They are 

 usually made of galvanized iron and large enough to hold the 

 bottles in crates on a car which may be wheeled into the oven. 

 An oven with two compartments is a great convenience, one for 

 heating th-e crates of glass bottles and the other for heating tin- 

 ware. 



Such ovens are heated by forcing steam into them through 

 perforated pipes laid on the bottom of the oven. A temperature 

 of 212 F. can be obtained in this way and this should be main- 

 tained for one-half hour or more. After heating, the hot bottles 

 should not be removed too suddenly from the oven, but allowed 

 to cool somewhat before the door of the sterilizer is opened. A 

 sudden rush of cold air into the oven chamber may crack the hot 

 bottles. 



826. A higher temperature of heating the bottles may be 

 obtained by using the high pressure sterilizing ovens which are 

 made to stand several pounds of steam pressure. The greater the 

 pressure the higher the temperature and the shorter the time 

 necessary to expose the bottles and utensils in order to destroy all 

 germ life. 



