374 HYDRAULICS 



X. 0017 = 17 ft. This makes the piezometric elevation at Oi 

 60017 = 583 ft. As this is greater than 556, the elevation 

 of Oi, and also greater than 550, the elevation of B, the 30-in. 

 pipe may be used for the main A. The heads for pipes B 

 and C are, respectively, 583-550 = 33 and 583-350 = 233. 



The corresponding values of - are 33 -i- 6,000 =.0055, and 



233 -=-4,000 = .0583. Knowing these values and the discharges, 

 the diameters can be taken from the table. They are 14 in. 

 for pipe B and 8 in. for pipe C. 



In carrying the main to the next branch point Oi, the possi- 

 bilities of choice of size are greater. But since the point H, 

 11,000 ft. away, is at an elevation of 400, it is desirable to 

 reduce the head as little as may be, and it will be assumed that 

 an effective head of 50 ft. will give necessary pressures without 

 making the pipes too large. The effective head in J being 50 



ft. in 2,000, the value of - is 50 -i-2,000 =.025; and from the 

 table, the pipe necessary to carry 12 cu. ft. per sec. with this 

 value of is found to be between 14 and 16 in. Using the 14-in. 



pipe, the value of - is .033; h = 2, 000 X. 033 = 66 ft., and, 

 therefore, the piezometric elevation atOjis 583 66 = 517 ft. 

 Proceeding as for the branches B and C, the value of - 

 for E is found to be .0355, which, by the table, requires an 

 8-in. pipe; for D, = .0195, which, by the table, requires 



a 10-in. pipe. 



Still bearing in mind the elevation of 400 at H, an effective 

 head of 50 ft. will be assumed between 2 and Os, so that 

 the piezometric elevation at the junction 03 will be 517 50 



= 467. The pipe K, then, will have a value of -of 50-7-3,000 



= .017; and it is found by the table, that for a delivery of 6.5 

 cu. ft. per sec., a 14-in. pipe is a little too large; it may. 



