138 EVAPORATED MILK STERILIZING 



other form of sterilizer is the continuous sterilizer in which the 

 unsterilized cans pass into and the sterilized cans escape from 

 the heating chamber in continuous procession. 



Loading the Batch-Sterilizer. The sealed tin cans are 

 placed in heavy iron trays, usually holding twenty-four 16-ounce 

 cans or six 1-gallon cans. The loaded trays are slid and locked 

 into the framework in the interior of the sterilizer. The sterili- 

 zer is closed with heavy iron doors and the framework is put 

 in motion. In some makes of sterilizers the interior consists of 

 a large perforated iron box revolving on its axis. In this case 

 the cans are simply piled into this box, no trays being used. 



Uniform Distribution of Heat. Where no water is used in 

 the sterilizer during the sterilizing process, it is important that 

 there be a free air space between every two layers of cans, so 

 as to allow the steam to circulate freely and to come in direct 

 contact with every can. When the cans are piled into the ster- 

 ilizer six to twelve layers deep without any free air space be- 

 tween layers, the cans in the center do not receive as much heat 

 as those at the sides, ends, top and bottom. This causes irreg- 

 ular heating and imperfect sterilization. 



A satisfactory means of insuring even distribution of heat 

 is to fill the sterilizer about one-thirdful of water, so that, when 

 the sterilizer is in operation the cans pass through this water, 

 with each revolution of the frame work. Water distributes the 

 heat uniformly, rapidly and there is no danger of the formation 

 of air' pockets between the cans. Since the heat is applied by 

 steam under pressure, the temperature of the water is equal to 

 that of the steam in the sterilizer. This precaution is especially 

 necessary in the case of baby-size cans (eight ounces) which are 

 usually piled in stacks more than two deep. When sterilizing 

 in the absence of water there is danger of lack of uniformity of 

 the amount of heat they receive. The uniform distribution of 

 the steam by the perforated steam distributing pipe in the bot- 

 tom of the sterilizer is essential for uniform heating of all the 

 cans. If the perforations in this pipe become enlarged due to 

 wear, or in case of an iron pipe due to rusting, or if the cap at 

 the end of the pipe happens to come off, the heat distribution- 

 is bound to lack uniformitv. 



