replying to MLD, Rick Rayfield wrote:

lot

Quick calculation ---pi/4 washes out: Area of a 6" pipe-6^26. Area of two 4"
pipes is 2*4^22. 36/32=1.125--so 6' pipe has about 12.5% more flow area than two

4' pipes. Just agreeing with your numbers--mental exercise for me too g MLD

Most of the answers address the problem presented. But the question asked was

about the "volume"of the four and six inch diameter pipes. Roughly, with a

cross section of 12 square inches, a foot of four inch diameter pipe has 144

cubic inches, or 1/12 cubic foot.The six pipe has a rough cross section of

about 27 square inches, or about 1/5 cubic foot per foot of pipe. Or simply,

the six inch pipe for the same length has a volume of a bit more than twice

the volume of the four inch pipe. Last time I looked, four inch pipe is a lot

less than half the price of six inch pipe. So if cost or distributing the

flow are factors, the smaller pipe(s) may be the better answer.

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