ECONOMIC OPERATION OF CREAMERY. 333 



The foaming or priming of boilers is due chiefly to: 



1. Too much water in the boiler. 



2. Working the boiler beyond its capacity. 



3. Allowing mud and minerals to accumulate in boiler. 



4. Using too much of certain boiler compounds. 



5. Some water naturally contains a large percentage of 



certain minerals which are conducive to foaming. 

 The Injector. — The injector on the boiler frequently causes 

 the operator some annoyance by refusing to work. The common 

 causes of this are : 



1. Too low boiler steam pressure. 



2. Steam obtained from a pipe already supplying steam 



for other purposes. 



3. Leaks in suction pipe due to shortage of supply pipe 



or holes in pipe. 



4. Too hot supply water. 



5. Scale in injector, preventing proper working of valves. 



6. Steam containing too much water. 

 Oil-separators. — Considerable saving can be accomphshed in 



a creamery if the exhaust steam is utilized. This steam may 

 be used for pasteurizing the skim-milk, for heating the milk 

 previous to separation, for heating the creamery, and for heat- 

 ing the water for the boiler. 



The exhaust steam contains considerable oil and should be 

 purified before it is used for any other purposes. Several 

 forms of these steam purifiers are on the market. They are 

 simple, inexpensive, and can be attached to the exhaust-pipe 

 of any engine. 



All steam and water pipes should be carefully drained in 

 the winter to prevent freezing. 



Belts, Pulley and Speed Calculation. — The length of a belt 

 may best be determined by measuring over the two pulleys 

 with a tape or a string. 



To calculate the size of a drive pulley when the speed 

 of it is known, the diameter of the driver pulley is multiplied 

 by its speed, the product divided by the speed of the driven 



