8 BULLETIN 849, U. S. DEPARTMENT OF AGRICULTURE. 



From the ideal sanitary standpoint class 1 is to be preferred. Most 

 dealers, however, do not consider it objectionable to pump the milk 

 before pasteurization, provided the pump is of the right type and 

 properly taken care of. The economy of dumping milk and leaving 

 the cans on the ground floor is of considerable importance and much 

 labor, time, and power may be saved by handling cans in that way 

 rather than by elevating the full cans and, after dumping, sending 

 them back on an elevator. Where there is not room enough on the 

 ground floor for weighing, sampling, and grading it may be con- 

 venient to send the milk upstairs in cans. This system as a rule is 

 more expensive, as is shown later in Table 2. 



3. Pump to higher level, then gravity. — The milk is dumped into 

 a tank on the first floor and pumped to a floor above, whence it flows 

 through the various pieces of apparatus by gravity, without the fur- 

 ther use of a milk pump. 



Some of the most modern large plants, which vary in height from 

 2 or 3 stories upward, come under class 3. It is less objectionable to 

 pump milk before pasteurization, when contamination can do less 

 harm, than after. This type of plant also has the desirable feature 

 of dumping and weighing the milk on the ground floor and is more 

 economical in receiving milk than plants in classes 1 and 2. 



4. Pump to higher level, then gravity and pump. — The milk is 

 pumped from the first to a floor above. From that point it is handled 

 by pumps, or partly by pumps and partly by gravity. 



Many of the larger plants belong to class 4. This type has the 

 economical advantages of the plants of class 3 and in addition per- 

 mits greater economies in labor by the fact that the various pieces of 

 apparatus are comparatively close together, and in some cases on 

 fewer floors. In most of the plants of class 4 milk is pumped after 

 pasteurization and the number of milk pumps and length of milk 

 piping required are usually greater than in plants of the other classes. 

 Many of the plants studied in this class were comparatively old. 



5. Gravity, one story. — The milk is handled on one floor without 

 milk pumps. Large quantities of milk can not be handled rapidly 

 in such plants, and only the smaller plants come under this head. 

 The plants of this class include a few small ones where the pasteur- 

 izer was raised on a platform and the milk dumped directly into it. 

 Those handling between 501 and 1,000 gallons daily were raw-milk 

 plants. 



6. Pump, one story. — The milk is handled on one floor, one or more 

 pumps being used. Class 6 includes some of the less up-to-date 

 plants, which are usually frame buildings, built some time ago. The 

 amount of milk piping required is comparatively large. Many of 

 the smaller plants come under class 6 ; 48 out of a total of 55 handling 

 less than 500 gallons each dailv were in this class. A few of the 



