90 EXPERIMENT STATION RECORD. 



ticular lift at some particular speed. The complete conditions of each test 

 were also entered in tabular form and a summary of results tabulated. 



For these 11 pumps the highest efficiency ranged from 33 per cent for a 6 in. 

 pump (practically new) operated at 855 revolutions per minute against a head 

 of 35 ft. discharging 600 gal. per minute, to 56.5 per cent for a 6 in. pump 

 (which had been used for several years) operated at 570 revolutions per min- 

 ute against a head of 34 ft., discharging 500 gal. per minute. 



Marked discrepancy was found between the ratings given the pumps in the 

 manufacturers' catalogues and those shown by test. " Instead of rating pumps 

 by the so-called 'economic capacity,' it would greatly add to the advantage of 

 the prospective purchaser If the manufacturer should publish tables or exhibit 

 curves based on reliable tests from which one might choose the size of pump 

 and determine the speed which would give the greatest economy or highest 

 efficiency for the desired discharge at the given head. . . . 



" Large pumps show better efficiencies than small ones, hence it may be 

 better to use a pump of over rather than under size, other conditions being the 

 same." 



"xis a final conclusion, it may be said that the best pump for any given set 

 of conditions is not necessarily the one giving the highest efficiency since the 

 question is one involving all the various factors which enter into the cost of 

 operation. Thus a pump of high efficiency might be more expensive than one of 

 lower efficiency so that, if, as is not infrequently the case, the pump is used only 

 a few months out of the year, the saving in fuel effected by the pump of higher 

 efficiency may be more than balanced by the greater yearly interest charge. 

 Again a pump of certain capacity might require a higher speed than another 

 pump of similar capacity and the same or perhaps slightly lower efficiency. 

 Other conditions being the same the pump of lower speed should be chosen 

 because of its probable longer life." 



Practical deductions drawn from the test as applied to different conditions 

 are also presented and discussed. 



Bagasse drying', E. W. Kerr and H. A. Nadler (Louisiana Stas. Bui. 128, 

 pp. 3-40, figs. 7, pi. 1). — Continuing previous studies (E. S. R., 22, p. 115) the 

 problem of utilizing the waste smoke-stack heat for drying bagasse for the 

 purpose of obtaining a greater fuel value for this material was studied with 

 particular reference to Louisiana conditions, where the bagasse usually con- 

 tains between 52 and 55 per cent of moisture. 



The dryer used in the tests was designed to be operated in connection with 

 a 100-horsepower boiler and consisted essentially of a rectangular sheet iron 

 box about 4 by 6 ft. and 20 ft. high having within it 6 inclined shelves 4 ft. 

 square and supported on a framework of angle irons. The bagasse is let in 

 at the top of the apparatus where it falls upon the uppermost inclined vibrating 

 shelf, and from which it slides to each of the other shelves in turn until the 

 bottom is reached, where it comes out, passing through mechanically operated 

 doors. The smokestack gases are conducted into the bottom of the dryer. 

 The necessary draft is induced by a 55-in. fan, which is placed near the top 

 of the apparatus. The cost of the apparatus exclusive of the engine for driving 

 it was $1,000. 



The following results were obtained from some 40 evaporative boiler tests, 

 the advantage due to drying being measured by the weight of water evaporated 

 per pound ot bagasse burned : 



" The average moisture in the bagasse entering the dryer was 54.3 per cent, 

 and leaving it, 46.4 per cent, which means that 14.5 per cent of the moisture 

 in the bagasse was removed by the drying process. The average equivalent 

 evaporation from and at 212° F. per pound of wet bagasse burned was 1.63 



