42 
BULLETIN U% U. S. DEPARTMENT OF AGRICULTURE. 
system is a closed one a circulation- will be maintained due to the 
difference in temperature of the water in the heater and that in the 
piping, thus making it possible at any time to draw off hot water 
through the hose connections. The clearance through the pump is 
sufficient to allow the water to pass through when the pump is not in 
operation. The water supply required to make up for that used in 
feeding the boiler for washing and for leakage is to be furnished 
from a pressure system, either from the city supply lines or from an 
overhead tank. The connection should be made through a check and 
stop valve, as shown. Stop valves are shown at the different units for 
controlling the supply of steam or hot water. 
DISTRIBUTION OF HEAT ENERGY FROM COMBUSTION OF COAL. 
Table 7 shows the distribution of the heat energy obtained from 
the combustion of the coal in the boiler furnace in an average gath- 
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Fig. 13. — Graphic illustration of the distribution of heat energy between the coal pile 
and machinery in an average creamery making 500,000 pounds of butter annually 
from pasteurized cream, live steam being used for all purposes. 
ered-cream plant making approximately 500.000 pounds of butter 
annually. The results are illustrated graphically in figure 13. The 
figures are based on actual tests and on careful estimates. The type 
of creamery selected is one in which all heating is done by live steam 
direct from the boiler. The distribution of heat energy covers a 
full day's operation, starting with raising steam in the boiler and 
ending: when the fire in the furnace is burned out. 
By studying the following table of the heat losses it will be noted 
that many items are excessive and can either be eliminated entirely 
or be greatly reduced. The loss of coal at the plant is one that can be 
entirely eliminated by exercising care in handling. It is often the 
case that the coal is stored some distance from the boiler room, neces- 
sitating its transfer from the bunker to the boiler by means of a 
