46 BULLETIN 747, U. S. DEPARTMENT OF AGRICULTURE. 



tabic il i.s estimated as averaging only 3 per cent, it often amounts 

 to several times as much. In addition to cutting down the passage 

 of heat it causes the plates to become overheated and is often the 

 direct cause of explosions. Creamery boilers as a rule are not cleaned 

 internally at regular intervals, and the scale is allowed to form until 

 it greatly reduces the efficiency of the boiler and in extreme, cases is 

 liable to cause an explosion. The remedy lies in keeping the internal 

 parts of the boiler thoroughly clean, either by treating the feed water 

 with chemicals before admitting it to the boiler, or by cleaning 

 mechanically at regular intervals. It is possible to eliminate entirely 

 the heat loss through scale formation. 



Leak}' pipe joints, valve stems, blow-off valves, etc., are the rule 

 instead of the exception in many small plants. This is due entirely 

 to carelessness. It is an easy matter to stop leaks in pipe joints, 

 pack valve stems, and regrind the blow-off valve, and thereby stop 

 leakage losses entirely. 



Heat losses through radiation from steam piping can easily be re- 

 duced 85 per cent by covering the bare pipes with a good grade of 

 pipe covering, thus reducing the loss to a negligible quantity. 



The losses due to engine friction and bearing, belt, and shaft fric- 

 tion may be reduced by better lubrication, proper size and tension 

 in the belts, and careful alignment of the shafting. Small pla>ts 

 in particular often suffer power loss through an unnecessarily large 

 amount and from poorly installed and maintained shafting. With 

 care these losses can be reduced at least one-half in the average 

 creamery. 



We now come to the heat consumed in the useful work. The heat 

 actually used in the engine for pasteurizing cream, heating milk 

 before separation, heating starter and wash water, and steaming and 

 drying cans amounts to only 6.3 per cent of the total heat units con- 

 tained in the coal consumed in a day's operation. The heat lost in the* 

 exhaust steam amounts to 9 per cent of the total in the fuel. Exclusive 

 of the heat energy consumed in useful work in the steam engine only 

 5.3 per cent of the heat in the fuel is used for other purposes. The 9 

 per cent of the total heat in the fuel lost in the exhaust steam, there- 

 fore, is more than sufficient to perform all the heating required in the 

 creamery, and also to heat the boiler-feed water. 



Table 8 is based on the same plant as that covered by Table 7, and 

 shows the possible distribution of heat energy through improvements 

 in the plant. Table 7 is based on 1,000 pounds of coal burned to 

 produce a certain amount of work. Table 8 shows that after stopping 

 leaks, utilizing the exhaust steam, and otherwise improving the 

 operation of the plant the quantity of coal consumed in performing 

 the same amount of work was only 470 pounds, or less than one-half 

 the former amount. : 



