Hazen-Williams equation

WeBBusterZ

Hazen-Williams equation is a popular approach for the calculation of head loss of liquid in piping systems. In this method, Hazen-Williams coefficient is introduced to the equation, the coefficient eliminates the need for using Reynolds number. The Hazen-Williams coefficient is mainly used to account for the pipe roughness or efficiency.

Hazen-Williams equation

Different formats for this equation is specified below

Equation 1 (US Units)

Hazen-Williams equation for head loss is shown below:

Hazen-williams equation 1

 

 

 

Where;
H = frictional head loss, ft
L = length of pipe, ft
D = inside diameter of pipe, ft
Q = flow rate, ft3/s
C = Hazen-Williams C factor or roughness coefficient, dimensionless

Equation 2 (US Units)

Hazen williams equation 2

 

 

 

Where;

H = friction loss, ft of water per 1000 ft of pipe
Q = flow rate, gal/min
D = inside diameter of pipe, in
C = Hazen-Williams C coefficient, dimensionless

Equation 3 (US Units)

Hazen-williams equation 3

 

 

 

Where;

Pmi = friction loss, psi per mile of pipe
Q = flow rate, gal/min
D = inside diameter of pipe, in
C = Hazen-Williams C coefficient, dimensionless

Equation 4 (US Units) – Flow rate

Hazen-williams flow rate equation

 

 

Where;

H = friction loss, ft of water per 1000 ft of pipe
Q = flow rate, gal/min
D = inside diameter of pipe, in
C = Hazen-Williams C coefficient, dimensionless

Equation 5 (SI Units)

Hazen-williams equation 5

 

 

Where;

Q = flow rate, m3/h
D = pipe inside diameter, mm
Pkm = frictional pressure drop, kPa/km
SG = liquid specific gravity (water = 1.00)
C = Hazen-Williams C factor, dimensionless

Common values for the Hazen-Williams coefficient C are listed in the table below:

Pipe material C Factor
Brick 100
Cast iron (old) 100
Iron (worn/pitted) 60 – 80
Polyvinyl chloride (PVC) 150
Smooth wood 120
Smooth masonry 120
Smooth pipes (all metals) 130 – 140
Vitrified clay 110

Read about another popular equation for head loss calculations using Darcy-Weisbach equation

Useful software

Useful mobile applications

Next Post

Difference between Fanning friction factor and Darcy friction factor

Contents1 What is the Difference between Fanning friction factor and Darcy friction factor?2 Fanning friction factor3 Darcy friction factor4 What about Moody chart?4.1 Other Resources4.2 USEFUL SOFTWARE4.3 USEFUL MOBILE APPLICATIONS What is the Difference between Fanning friction factor and Darcy friction factor? Fanning friction factor The Fanning friction factor is […]
Head loss calculation