Related Engineering & Construction Calculators

How to Use the Pipe Flow Calculator

1. Select Units: Choose between Metric or Imperial units for your calculations.
2. Enter Pipe Properties: Select the pipe material to auto-fill a typical Hazen-Williams C-factor, or enter your own. Input the pipe's internal diameter and total length.
3. Enter Pressure Drop: Input the difference in pressure between the start and end of the pipe.
4. Calculate: See the resulting flow velocity and volumetric flow rate.

Understanding the Hazen-Williams Equation

The Hazen-Williams equation is an empirical formula used in hydraulic engineering to calculate the velocity of water in a pipe. It is widely used for designing water distribution systems, fire sprinkler systems, and irrigation networks. The formula relates the flow of water to the physical properties of the pipe and the pressure drop caused by friction.

The Formula

• V: Flow Velocity
• k: A conversion factor for the unit system (0.849 for metric, 1.318 for imperial)
• C: The Hazen-Williams roughness coefficient.
• R: The hydraulic radius of the pipe (Diameter / 4).
• S: The slope of the energy line (pressure drop / pipe length).

What is the C-Factor?

The C-factor is a dimensionless number that represents the roughness of the inside of the pipe. A higher C-factor means a smoother pipe, which results in less friction and a higher flow rate. Over time, pipes can corrode or build up scale, which lowers their C-factor.