What should be the diameter of the trunk
pipe, in which it will be assumed that ten bonds or elbows are necessary?
In the first instance, it is convenient to suppose that the trunk pipe
may be of uniform diameter throughout. Then the value of _l_ will be
100 (from gasholder to main building) + 250 (within the building) + 50
(equivalent of 10 elbows) = 400. The maximum value of Q will be (50 x
0.7) + (50 x 1.0) = 85; and the value of _h_ will be 1 - 2.5 - 1.5.
Then using formula (i), we have:
d = 0.045122((85^2 x 400)/1.5)^(1/5) = 0.045122(1,926,667)^(1/5)
= 0.045122 x 18.0713 = 0.8154.
The formula, therefore, shows that the pipe should have an internal
diameter of not less than 0.8154 inch, and consequently 1 inch (the next
size above 0.8154 inch) barrel should be used. If the initial pressure
(i.e., at outlet of purifiers) could be conveniently increased from 4 to
4.8 inches, 3/4 inch barrel could be employed for the service-pipe. But
if connexions for burners were made immediately the pipe entered the
building, these burners would then be supplied at a pressure of 4.2
inches, while those on the extremity of the pipe would, when all burners
were in use, be supplied at a pressure of only 2.
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