TABLE OF TEST RESULTS.

After the test has been made and properly worked up, as heretofore described, collect all the results of the test on one sheet, so that they can be kept in convenient form for reference and for comparison with later tests. A brief form of arranging the results is as follows:

1. Date of test............................................................................... May 20, 1918
2. Duration of test..........................................................................hours10
3. Weight of coal used...................................................................pounds5,000
4. Weight of water fed and evaporated...........................................do.35,000
5. Average steam pressure, gauge...................................................do.100
6. Average feed-water temperature.................................................°F.180
7. Factor of evaporation.................................................................1.0727
8. Equivalent evaporation from and at 212° F..................................pounds37,545
EFFICIENCY.
9. Efficiency of boiler and furnace...................................................per cent54
CAPACITY.
10. Boiler horsepower developed...................................................109
11. Builders' rated horsepower.......................................................150
12. Percentage of rated horsepower developed...............................per cent73
ECONOMIC RESULTS.
13. Actual evaporation per pound of coal........................................pounds7
14. Equivalent evaporation from and at 212° F................................pounds7.5
per pound of coal as fired,
15. Cost of coal per ton (2,000 pounds).........................................$3.60
16. Cost of coal to evaporate 1,000 pounds from and at 212° F.....$0.24

HOW TO USE THE TEST RESULTS.

The object of working up a test is to obtain a clear idea as to the efficiency of operation of the boiler or its operating cost. Consequently, after the calculations have been made, they should be used as a basis for study with the idea of improving the boiler performance.

Take the matter of boiler efficiency, for example, as found from the test mentioned. Its value was 54 per cent. This is altogether too low and indicates wasteful operation. The efficiency of a hand-fired boiler ought not to be less than 65 per cent, and it can be increased to 70 per cent by careful management under good conditions.

The chart in figure 3 can be used to indicate the evaporation that should be obtained in order to reach a desired efficiency. Suppose, for example, that it is desired to know how much water per pound of coal must be evaporated to produce a boiler efficiency of 65 per cent with coal having a heating value of 13,500 B. t. u. per pound.

Locate 13,500 at the bottom of the chart, follow the vertical line until it meets the diagonal marked 65 per cent, and then from this point follow the horizontal line to the left-hand edge, where the figure 9 is found. This means that the equivalent evaporation from and by 212° F. per pound of coal must be 9 pounds of water. If the steam pressure is 100 pounds gauge, and the feed-water temperature is 180° F. the factor of evaporation is 1.0727, then the actual evaporation must be 9 ÷ 1.0727 = 8.36 pounds per pound of coal. In other words, to increase the efficiency from 54 per cent to 65 per cent under the same conditions of pressure and feed-water temperature, it would be necessary to increase the actual evaporation from 7 pounds to 8.36 pounds. This would mean practically 20 per cent more steam from the same weight of coal used.