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Pipe Capacity Calculator Flowing Full

Manning's Equation for Pipe Flow:

\[ Q = \frac{1}{n} \times A \times R^{\frac{2}{3}} \times S^{\frac{1}{2}} \]

meters
m/m

1. What is a Pipe Capacity Calculator?

Definition: This calculator estimates the flow capacity of a pipe flowing full using Manning's equation.

Purpose: It helps engineers and designers determine the maximum flow rate in circular pipes under gravity flow conditions.

2. How Does the Calculator Work?

The calculator uses Manning's equation:

\[ Q = \frac{1}{n} \times A \times R^{\frac{2}{3}} \times S^{\frac{1}{2}} \]

Where:

  • \( Q \) — Flow rate (m³/s)
  • \( n \) — Manning's roughness coefficient
  • \( A \) — Cross-sectional area (m²)
  • \( R \) — Hydraulic radius (m)
  • \( S \) — Slope (m/m)

Explanation: The flow rate depends on pipe characteristics (roughness and diameter) and the energy slope.

3. Importance of Pipe Capacity Calculation

Details: Proper pipe sizing ensures adequate flow capacity, prevents overflows, and optimizes system performance.

4. Using the Calculator

Tips: Enter Manning's n (default 0.013 for concrete pipes), pipe diameter in meters, and slope (m/m). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical Manning's n values?
A: 0.013 for concrete, 0.011 for PVC, 0.015 for corrugated metal, and 0.022-0.035 for natural channels.

Q2: How is hydraulic radius calculated for full pipes?
A: For full circular pipes, R = D/4 (diameter divided by 4).

Q3: What slope should I use?
A: Typical slopes range from 0.5% (0.005) to 2% (0.02) for drainage pipes.

Q4: Does this work for partially full pipes?
A: No, this calculator assumes full pipe flow. Different equations are needed for partial flow.

Q5: How accurate is Manning's equation?
A: It's an empirical equation accurate for turbulent flow in rough pipes, typical for water applications.

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