Volume 1

Modern sanitary engineering / by Gilbert Thomson.

  • Thomson, Gilbert.
Date:
1912-1921
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Modern sanitary engineering / by Gilbert Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    C is the figure which it is suggested in the text may, for a 4-inch pipe, be taken approximately as 62, but which might be calculated as follows, taking the gradient as given above and the coefficient of roughness as '013. TaHng C as 62, then F= 62 X ^ = 2-83, and^ = ttt^ = 3-14 X {If = -087 square foot. So Q = 2-83 X -087 = 246 cubic foot per second. Multiplying this hy 6i gives 1-537 gallons per second. If n had been taken = -Oil, the value of C would have been 79-7. The velocity would have been 3-64, the cubic feet per second would have been 0-317, and the gallons per second 1'98. This example therefore shows not only how the calculation is made, but also the futility of expecting to get precise results from any such calculations. The value of n has to be filled in according to the judgment of the calculator, and the selection makes a material difference in the result. The above figures are carried to a degree of minuteness far beyond that required for any practical purpose, merely to illustrate the method. It might be added that a pipe will not run absolutely full unless under pressure, as its carrying capacity is greater when nearly full than when quite full. This is due to the fact that the hydraulic radius is greater when the pipe is not quite full _ 41-6 + 139-308 + '112 ~ 1 + [41-6 + -112] -013 X 3-464
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