USE OF CONCRETE PIPE IN IRRIGATION. 
25 
carry about 20 per cent more water than shown by table, especially 
where there is danger of any clogging by debris, or pipe is very rough. 
Table gives the carrying capacities of concrete pipe in miner's inches computed 
to the nearest 5 miner's inches. 1 
[Fall 
in feet per 100 feet.] 
Diameter of pipe. 
0.1 
0.2 
0.3 
0.4 
0.5 
1.0 
2.5 
5.0 
Miner's 
inches. 
10 
20 
35 
60 
85 
120 
160 
225 
275 
350 
650 
Miner's 
inches. 
10 
25 
50 
80 
120 
170 
230 
310 
400 
500 
900 
Miner's 
inches. 
15 
35 
60 
110 
150 
210 
285 
380 
485* 
620 
1,100 
Miner's 
inches. 
20 
40 
70 
115 
170 
235 
330 
435 
525 
710 
1,275 
Miner's 
inches. 
20 
45 
80 
120 
200 
275 
450 
500 
625 
800 
1,425 
Miner's 
inches. 
30 
60 
110 
180 
275 
400 
550 
700 
900 
1,150 
Miner's 
inches. 
45 
85 
180 
275 
400 
600 
825 
1,100 
1,400 
Miner's 
inches. 
60 
140 
10 inches 
250 
1 One miner's inch is here equivalent to the one-fiftieth part of a second-foot and is nearly equal to 9 
gallons per minute. 
Engineers and pipe contractors will have no trouble in interpret- 
ing the above table, but for the convenience of irrigators without 
engineering experience, a few examples will be given to enable them 
to estimate sizes of pipe for various conditions. 
The retarding influence to flow of water known as friction is com- 
mon to all pipes, the intensity of the friction increasing with the ve- 
locity of the water and the roughness of the pipe. If the pipe is laid 
down grade the fall may be sufficient to overcome friction. When the 
water is pumped if the fall is not enough to carry the desired quantity 
then the water will rise in the standpipe at the entrance until there is 
sufficient head to force the water through. Of course if the stand is 
not high enough water will spill over the top. If the pipe runs up 
hill, when water is pumped, the delivery box or relief stand at the 
pump end must be high enough to overcome the difference in eleva- 
tion between the entrance and outlet of the pipe, plus the head re- 
quired to overcome friction in the pipe. In practice such standpipes 
should not be high enough to develop unsafe pressures on the pipe. 
Example 1. 
Assume that an irrigator has acquired the right to the use of 200 
miner's inches of water and wishes to install a pipe to carry this 
amount to his farm, a distance of 2,000 feet. If levels show there is 
a total fall of 6 feet between entrance and outlet, he will have a fall of 
0.3 foot per 100 feet. From the table under vertical column of 0.3 
(fall per 100 feet) it is seen that a 16-inch pipe will carry 210 miner's 
inches. If he can fill the standpipe at entrance 4 feet deep, he will 
have 4 feet additional head on the pipe, or a total head of 10 feet (in- 
cluding fall). This gives him 0.5 foot fall per 100 feet. The table 
3445°— 21 — -4 
