Pipe Capacity Calculator Metric

Manning's Equation for Pipe Flow:

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

Flow Capacity (Q):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Manning's Equation for Pipe Flow?

Manning's equation is an empirical formula that calculates the flow capacity in open channels and pipes. For pipe flow applications, it estimates the volumetric flow rate based on pipe characteristics and slope.

2. How Does the Calculator Work?

The calculator uses Manning's equation:

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

Where:

\( Q \) — Volumetric flow rate (m³/s)
\( n \) — Manning's roughness coefficient
\( A \) — Cross-sectional area of flow (m²)
\( R \) — Hydraulic radius (m)
\( S \) — Slope of the energy line (m/m)

Explanation: The equation calculates flow capacity based on pipe geometry, surface roughness, and slope gradient.

3. Importance of Pipe Flow Calculation

Details: Accurate pipe flow calculation is essential for designing drainage systems, sewer networks, irrigation channels, and various hydraulic engineering applications.

4. Using the Calculator

Tips: Enter Manning's roughness coefficient (typical values: 0.010-0.015 for smooth pipes, 0.012-0.017 for concrete pipes), pipe diameter in meters, and slope in meters per meter. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What are typical Manning's n values for pipes?
A: Common values range from 0.009-0.015 for smooth pipes like PVC, 0.012-0.017 for concrete pipes, and 0.021-0.026 for corrugated metal pipes.

Q2: How is hydraulic radius calculated for full pipe flow?
A: For a full circular pipe, hydraulic radius R = D/4, where D is the pipe diameter.

Q3: What is the range of applicability for Manning's equation?
A: Manning's equation is valid for turbulent flow conditions, which is typical for most practical pipe flow applications.

Q4: Can this calculator be used for partially full pipes?
A: This calculator assumes full pipe flow. For partially full pipes, additional calculations for flow area and hydraulic radius are needed.

Q5: How does pipe material affect the flow capacity?
A: Pipe material affects the roughness coefficient (n), with smoother materials having lower n values and thus higher flow capacities for the same slope and diameter.