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# Flow Rate Question

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Member Posts: 12
edited November 2016
Under proper conditions, the one of the following groups of pipes that give the same flow in gals/min as one 6" diameter pipe is (neglect friction) __________ pipes of __________ diameter each.
A) 3; 3"
B ) 4; 3"
C) 2; 4"
D) 3; 4"
If you can give an explanation too, that would be great.

• Member Posts: 41
edited November 2016
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https://www.scribd.com/doc/42212140/Pipe-Size-and-GPM-Chart

http://www.onicon.com/pdfs/0868-4-Velocity-to-GPM-01-16.pdf

Without much expertise, I say you might need D) 3; 4" to meet or exceed the flow capacity.
• Member Posts: 273
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B (6" circle has 28sq in, 3" circle has 7sq in, so 4 x 3" pipes has the same area as 1 x 6" pipe) credit to "circle calculator" & google.
Winter Park, CO & Arvada, CO
• Member Posts: 7,356
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You don't need Pi to calculate relative areas. Just square the diameters and add them up:

6x6 = 36
3x3 = 9

Ratio = 4:1