218 CLEAN MILK 



matically the supply of steam and heat, so as to correspond with and 

 produce the required temperature of the outflow of the pasteurized 

 product. These automatic thermo regulators should be accurate and 

 must be approved by the commissioner of health before being installed. 



A recording apparatus shall be installed upon all continuous pas- 

 teurizers operated within the city limits so as to record during oper- 

 ation the temperature of the pasteurized product as it flows from the 

 heater. The thermometer of this recording apparatus must be accu- 

 rate and kept immerged in the milk in such a way that it is not exposed 

 to escaping steam or other heat except the heated milk. 



The records made by this recording thermometer must be accurate 

 and made in a chamber which is kept under lock and key in the con- 

 trol of the department of health. 



'The automatic thermo regulating and recording apparatus may be 

 combined into one instrument and it is recommended that all pasteur- 

 izers be equipped with both appliances or the combination apparatus. 



(B) Held pasteurization. Whenever milk is held during pas- 

 teurization in such a manner that the process of pasteurizing is not a 

 continuous one, namely, a continuous flow of milk through the heating 

 or heat retaining chamber, the process shall be designated as " Held 

 Pasteurization." Such methods of pasteurization and pasteurization 

 appliances or systems installed and used shall be examined and approved 

 by the commissioner of health, or his duly appointed representatives, 

 when all of the following requirements are fulfilled : 



i. When the pasteurized product shows that over 99 per cent, of 

 the bacteria and all pathogenic bacteria contained in the raw product 

 have been destroyed. 



2. When the mechanism of the pasteurizer or pasteurizing system 

 is such that the three important elements, namely : the temperature, time 

 of exposure, and the quantity of milk exposed at one time, can be 

 readily kept under control and observation by the department of health. 



3. When the following conditions are complied with : 



A uniform heating of 140 degrees F. maintained for twenty min- 

 iates; 150 degrees F. maintained for 15 minutes; 155 degrees F. main- 



