THE FLOW OF WATEK IN WOOD-STAVE PIPE. 67 
velocity and entry head is found to be 0.303 feet. Therefore, the final 
figures are 9 g ~ = 0-536 = H. 
Again, referring to Plate X, at the intersection of Q = 63 and 
H = 0.536 the diameter of the required pipe is found to be 60 inches 
and the peak-load velocity to be 3.3 feet per second. The difference 
between the preliminary figure for combined velocity and entry heads 
and the final figure is not sufficient to warrant more trials. 
2. A power trunk line from a reservoir to a surge tank to convey 
a peak load of 700 second-feet is required. The length of pipe will 
be 11.3 miles, the total loss of head under peak load shall not exceed 
20 feet, and the value of head shall be sufficient to warrant a factor 
of safety of 15 per cent in designing. Required for comparison, the 
size of pipe for both a single and a double pipe line with the same loss 
of head. 
The length of pipe is so great that velocity and entry head may be 
ignored. 
One hundred and fifteen per cent of 700 = 805 second-feet. 
Eleven and three-tenths miles = 11.3 X 5,280 = 59.664 X 1,000 feet. 
||^| = 0.335 feet per 1,000 feet = H. 
Enter Plate X at Q = 805. Intersection of Q = 805 with H = 0.335 
is at D = 14.5 feet and at V = 5 feet per second. Thus a single pipe 
line 14.5 feet in diameter will convey the peak load at a velocity of 
about 5 feet per second. 
To study the possibilities of a double pipe line, turn to figure 6. 
Enter at intersection of diameter 14.5 feet and relative capacity 1. 
From this point the left slanting line intersects relative capacity 
line I on diameter line 135 inches or diameter line 11.25 feet. Thus 
twin lines each 11J feet in diameter will convey the given quantity 
of water with the same loss of head as will a single line 14§ feet in 
diameter. 
Pipe problems involving velocities less than 0.7 foot per second or 
more than 9 feet per second may be solved by the use of Plate VIII. 
With a straightedge join the two discharge scales at the given dis- 
charge. All points on the straightedge will now give simultaneous 
values of diameter, loss of head, and velocity. For instance, the 
dash-dot line representing 100 second-feet intersects the 84-inch pipe 
line on the H-line of 0.237 foot per 1,000 feet and on the V-line of 
2.58 feet per second. Thus an 84-inch pipe will convey 100 second- 
feet of water at a velocity of 2.58 feet per second with a loss of head 
of 0.237 foot per thousand feet of pipe. 
