KUTTER'S FORMULA 181 



and one-third full, with ^ = .015; tables of S and s, ranging 

 from S = i in 4 to S = i in 2640, or from 25 to .028 per cent. 



No. 84 gives, with other tables and discussions, tables 

 for circular pipes flowing full, the diameters ranging from 



5 inches to 20 feet, and with values for n of .on, .012, and .013. 

 A table of slopes is given varying from S = i per cent to 5 = .053 

 per cent, decreasing by small amounts, so that the table is very 

 convenient. 



To illustrate the use of Flynn's tables the following examples 

 are given, using No. 84: 



1. What are the velocity and discharge of an 8-inch sewer 

 flowing full on a grade of .4 per cent, n being assumed at .013? 



From the table for ^ = .013, and for a value of d = 8, cVR 

 is 31.00 and AcVll is 10.822. From a table of square roots, 

 Vo is .06325. Then v equals 3i.ooX.o6325, or 1.96 feet per 

 second, and Q is 10. 822 X. 06325, or .68 cubic foot per second. 



2. What will be the size of sewer required to carry off a 

 flow of 3.6 cubic feet per second, the grade being .125 per cent, 

 n being taken at .013? 



From the table for ^ = .013 a value of AcVR must be found 

 which multiplied by ^.00125 shall equal 3.6. This is 3.6 divided 

 by .0354, or 101.7, which corresponds to a diameter of i foot 



6 inches, the value_ required. Similarly the velocity will be 

 the product of cVR found in the same line, or 57. 80 X. 0354, 

 that is, 2.05 feet per second. 



3. On what grade must a 24-inch pipe be laid to secure a 

 velocity of 2.5 feet per second, n being taken at .on? 



From the table for w = .oii, and a diameter of 24 jnches, 

 is found equal to 87.36, which multiplied by Vs must 

 be 2.5. \/S is, therefore .0285, and 5, .0008, or .08 per cent. 



4. What grade is necessary to discharge 8.5 cubic feet of 

 sewage through a 20-inch pipe, and what will be the velocity, 

 n being .012? 



From the table for w = .oi2, and a diameter of 20 inches, 

 Ac\/R is 150.61, which multiplied by \/S must be 8.5; 

 must therefore be .05637 and S is .00267, or .267 per cent. 



