Angst,

Your math is wrong. Area is PI x r squared. Pi is the same in both equations so it will cancel out. If we are only interested in comparing the relative area of the cross section area of large pipe compared to the small pipe we can just use the diameter and square it.

Therefore: 1 3/4 squared = 3.06 small pipe
...............2 1/2 squared = 6.25 large pipe

Then: 6.25 divided by 3.06 = 2.04.

So the area of the 2 1/2 inch pipe compared to the 1 3/4 inch pipe is greater than 2. Thus the restriction of the smaller pipe would be greater than 2.

It the same fact that a 10 inch pipe will supply 100 1 inch pipes not only 10 because of the square factor.

P E H