34 



BULLETIN 1067, U. S. DEPARTMENT OF AGRICULTURE. 



the discharge side is 2 feet. The suction and discharge pipes are each 

 about 25 feet long, and the main shaft of the pump is about 3 feet 

 above average water level in the discharge canal. 



METHOD OP CONDUCTING THE TEST. 



Two tests were run on this plant. In the first the discharge of the 

 pumps was measured by Pitot tubes placed in the discharge pipes 

 at a distance of about 10 feet from the pumps. This proved to be so 

 close to the pump that eddy currents interfered with the proper 

 working of the tubes. The results for the quantity of water pumped 

 during the test were found to be too erratic to be of value. A week 

 later the test was run again on one unit with the Pitot tubes placed 

 in the suction pipes. The readings taken on the suction side were 

 very consistent. The lift used in computing the water horsepower 

 was obtained by reading gages set in the suction and discharge canals. 

 The fuel oil used in the engines, a distillate oil of specific gravity 

 0.875 at 72° F., was weighed in buckets by means of a spring balance. 



In the first test the indicated horsepower of the engine was measured 

 by an indicator using a 250 spring. In the second an 80 spring was 

 used with entire success. From 10 to 20 complete cycles were taken 

 on each card and the several areas were averaged. While the results 

 of the first test of the pumps are of no value, the results of the test 

 of the engine compare very well with the results of the second test 

 and are considered of value. Table 25 is a summary of the first 

 engine test. 



Table 25. 



Unit 

 No. 1. 



Unit 

 No. 2. 



Length of run, hours 



Revolutions per minute, average 



Average indicated horsepower 



Minimum indicated horsepower 



Revolutions per minute at minimum indicated horsepower 



Maximum indicated horsepower 



Revolutions per minute at maximum indicated horsepower 



Total pounds of fuel oil Nos. 1 and 2 



Pounds of fuel oil per indicated horsepower-hour 



Pounds per brake horsepower (assuming mechanical efficiency of 80 per cent) 



4 

 204 

 32.6 

 26.4 

 193 

 37.7 

 213 

 219.2 

 .74 

 .92 



4 



211 

 41.6 

 28.4 



183 

 50.6 



221 



During the second test on unit No. 1 the speed of the engine was 

 somewhat less than in the previous test, and the engine seemed to be 

 working much more smoothly. The results of the test are given in 

 Table 26. 



