Sewer Pipe Capacity Calculator
Manning Equation Flow
Calculate full-pipe flow capacity
Formula
V = (1.486/n) x R^(2/3) x S^(1/2) | Q = V x A | R = D/4 (full pipe)
Frequently Asked Questions
What is the Manning equation?
The Manning equation calculates gravity flow in open channels and partially full pipes: V = (1.486/n) x R^(2/3) x S^(1/2), where n is roughness, R is hydraulic radius, and S is slope.
What velocity should sewer pipes have?
Minimum 2 ft/s to prevent solids settling (self-cleansing velocity). Maximum about 10 ft/s to prevent erosion. Ideal range is 2-5 ft/s.
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