22 



BULLETIN" 1067, U. S. DEPARTMENT OF AGRICULTURE. 



nearly constant as possible, so as to obtain the efficiency under normal 

 conditions. Table 13 shows the results of the test. The indicated 

 horsepower given in the table is the mean of the two cards taken at 

 the beginning and end of each observation. 



Table 13. — First test of pumping plant in Jefferson drainage district No. 3, Lafitte, 



La., Feb. 22-23, 1913. 

 UNIT NO. 1, 48-INCH PUMP. 



Speed. 



Indicated 

 horse- 

 power. 







Actual 

 lift. 



Head 



on 

 pump. 



Useful 

 water 

 horse- 

 power. 



Efficiency. 



Discharge. 



Pump, 



engine, 



and 

 piping. 



Pump 



and 



engine. 



E. p. m. 

 103 



134.8 

 203.5 

 121.3 

 90.9 

 102.2 

 137.1 

 142.6 

 140.7 



Sec.-ft. 

 136.6 

 158.6 

 129.8 

 103.8 

 94.6 

 118.3 

 119.7 

 122.8 



G. p. m. 

 61,300 

 71,200 

 58,300 

 46,600 

 42,450 

 53, 100 

 53,750 

 55, 100 



Feet. 

 4.00 

 4.40 

 4.80 

 4.85 

 6.05 

 5.35 

 5.42 

 5,45 



Feet. 

 4.05 

 4.42 

 5.48 

 5.87 

 6.58 

 6.29 

 6.23 

 6.03 



62.0 

 79.2 

 70.8 

 57.1 

 65.1 

 71.9 

 73.5 

 75.9 



Per cent. 

 46.0 

 38.9 

 58.4 

 62.8 

 63.8 

 52.4 

 51.6 

 54.0 



Per cent. 

 46.6 

 39.2 

 66.6 



120.5 



101.5 



95.5 



100.5 



69.3 

 61.6 

 59.4 

 59.8 



108 



108 



109.7 





1105.8 



i 134. 1 



1123.0 



155,200 



15.41 



16.18 



169.4 



152.7 



160.3 









UNIT NO. 2, 48-INCH PUMP. 









121 



212.7 

 216.9 

 153.4 

 185.5 

 125.5 

 95.9 

 61.0 

 163.8 

 174.9 



170.4 

 176.7 

 147.7 

 158.7 

 133.1 

 115.4 

 82.9 

 122.1 

 120.1 



76,500 

 79,300 

 66,300 

 71,250 

 59,700 

 51,800 

 37,200 

 54,800 

 53,900 



3.38 



3.40 

 3.31 

 3.45 

 3.64 

 3.84 

 3.70 

 6.25 

 6.85 



4.40^ 



3.00 



4.03 



5.16 



4.01 



3.71 



4.08 



6.84 



7.17 



65.4 

 68.2 

 55.5 

 62.1 

 55.0 

 50.3 

 34.8 

 86.5 

 93.5 



30.7 

 31.4 

 36.2 

 33.5 

 43.8 

 52.5 

 57.1 

 52.8 

 53.5 



40.1 

 35.4 

 44.1 

 50.1 

 48.3 



121 



109 



116 



101.7 



93.5 



81.5 



62.9 

 57.8 

 55.9 



114.5 



119 





1108.6 



U54.4 



1 136. 3 



161,170 



16.55 



17.00 



1 63. 5 



153.2 



156.9 





1 Mean. 



In testing unit No. 1 the actual head at the beginning of the test 

 was 4 feet and readings were taken up to 6 feet. It was then found 

 that the increase in head was too rapid to get proper readings, due 

 to the fact that the only water available for pumping was then in 

 the canal. It was therefore decided to siphon water back into the 

 canal with No. 2 unit while testing No. 1. This was done for the last 

 three observations, and as a result the actual head for those three 

 readings was 5.41 feet. The difference between the dynamic and 

 static head gives the friction losses in the pipes and at the entry and 

 discharge. Several inconsistencies appear in the friction losses 

 recorded which can only be accounted for by the fact that it is im- 

 possible to make very accurate readings on the suction and discharge 

 manometers of drainage units. Velocities were rather high, and the 

 suction and discharge pipes were so short that there seemed to be a 

 surging effect through the whole system at each revolution of the 

 engine corresponding to the variation in angular velocity at different 

 parts of the stroke. 



