Hazen-Williams Friction Loss Calculator

Calculation Result:

The result is calculated using the Hazen-Williams equation:

h_100ft = 0.2083 * (100 / C)^1.852 * Q^1.852 / D^4.8655

Where:

h_100ft: Friction head loss per 100 ft (ft H₂O/100 ft pipe)
C: Roughness coefficient
Q: Flow rate (gal/min)
D: Pipe diameter (inches)

What is the Hazen-Williams Equation?

The Hazen-Williams equation is an empirical formula used to calculate frictional head loss in pressurized water pipes. It is widely adopted in engineering for estimating energy losses caused by the friction between moving water and the inner surface of a pipe. Unlike other formulas, it assumes that the friction factor is independent of flow velocity or pipe diameter, making it particularly useful for practical applications.

The equation is expressed as:

h_100ft = k * (100 / C)^1.852 * Q^1.852 / D^4.8655

Where:

h_100ft: Friction head loss per unit length of pipe (ft H₂O/100 ft).
C: Roughness coefficient, depending on the pipe material (e.g., PVC, steel).
Q: Flow rate in gallons per minute (gal/min).
D: Inside diameter of the pipe in inches.
k: A unit conversion factor (0.2083 for imperial units).

How to Use the Hazen-Williams Calculator?

This step-by-step guide will help you use the Hazen-Williams calculator effectively to determine frictional head loss in water pipes:

Enter Flow Rate: Input the flow rate in gallons per minute (gal/min). This represents the volume of water flowing through the pipe.
Specify Pipe Diameter: Provide the inside diameter of your pipe in inches. This is crucial for accurate calculations.
Set Roughness Coefficient: Enter the Hazen-Williams roughness coefficient (C) based on your pipe material. For example, PVC typically has a value around 150, while older cast iron pipes may have a value of around 100.
Provide Pipe Length: Input the total length of your pipeline in feet. The longer the pipe, the greater the frictional loss.
Click Calculate: Press the “Calculate Friction Loss” button to compute the total head loss due to friction.
Review Results: The calculator will display the total head loss in feet of water (ft H₂O) and provide an explanation of its significance.

This tool is ideal for engineers designing water distribution systems or anyone analyzing fluid flow in pipelines. It simplifies complex calculations and provides quick results for practical use.