### Pipe Flow Calculator:

Use this pipe flow calculator to analyze the properties of water flowing in a gravity feed system. You only need to know the diameter of the pipe, the material it is made of, its length and drop in height. We use the Hazen-Williams equation for you to calculates the resulting velocity and discharge.

- Get pipe material type, pipe diameter, length and drop values.
- Find the hydraulic radius value i.e. diameter divided by 4.
- Calculate the slope of the power line, which is the pipe length divided by the drop.
- Get the area of circular tube.
- Change the values in the formulas.
- Perform mathematical operations to check the discharge and flow rate of a pipe.

When the flow of water in a pipe is due to gravity, it is called gravity flow of water. We can calculate the flow velocity of water using Hazen-Williams equation.

Hazen-Williams equation is valid only for water. The formula is dashed.

### Hazen Williams Equation:

Hazen Williams equation is the water flow velocity in the pipe V_{(ft/s)} in feet per second is equal to the is conversion factor k_{(ft)} in feet and multiply the roughness coefficient c_{(ft)} in feet and multiply the hydraulic radius R_{(ft)}^{0.63} and multiply the slope of the energy line s_{(ft)}^{0.54} in feet.Hence the Hazen Williams equation can be written as

V_{(ft/s)}=k_{(ft)}*c_{(ft)}*R_{(ft)}^{0.63} *s_{(ft)}^{0.54}

V=is the water flow velocity in the pipe (m/s is for the metric system,ft is for the imperial system)

C=is the roughness coefficient

R=is the hydraulic radius

S=is the slope of the energy line

K=is conversion factor (k=0.849 for the metric system k=1.318f or the imperial system)

Hydraulic radius is defined as the ratio of area and perimeter of the pipe.As the pipe is in a circular shape

Hydraulic radius R=A/p=π*r^{2}/2π*r=r/2=d/4

The slope of the energy line is obtained by dividing the pipe length by the drop

The formula to get the flow discharge Q is as follows

Q=A*V

### Example:1

Calculate the velocity and discharge of a copper pipe having 0.6ft in diameter.The pipe is 25 ft long and the difference in height between the starting and endpoints of the pipe is 4 ft.

### Answer:

Given that

Diameter of pipe d=0.6ft

Pipe length =25ft

Drop=4ft

Radius of the pipe r=d/2=0.6/2=0.3ft

Cross-sectional area A=π*r^{2}=3.14*0.3^{2}

=0.2826ft^{2}

Perimeter of the pipe p=2*π*r

=2*3.14*0.3

=1.884ft

Hydraulic radius R=A/p

=0.2826/1.884

=0.15ft

Slop s=drop/length of pipe

=4/25=0.16

As the pipe material is copper, the roughness coefficient c=140

Hazen Williams equation for velocity v=K*c*R^{0.63}*s^{0.54}

Substitute the values k=1.318 ft constant value

V=1.318*140(0.15)^{0.64} *(0.16)^{0.54}

V=20.368ft/s

Flow discharge Q=A*v

=0.2826*20.368=5.7562 ft^{3}/s

Therefore, the water flow rate is 20.368ft/s and flow discharge is 5.7562 ft^{3}/s

### Example:2

Calculate the velocity and discharge of a copper pipe having 0.5ft in diameter.The pipe is 15 ft long and the difference in height between the starting and endpoints of the pipe is 5 ft.

### Answer:

Given that

Diameter of pipe d=0.5ft

Pipe length =15ft

Drop=5ft

Radius of the pipe r=d/2=0.5/2=0.25ft

Cross-sectional area A=π*r^{2}=3.14*0.25^{2}

=0.1963ft^{2}

Perimeter of the pipe p=2*π*r

=2*3.14*0.25

=1.57ft

Hydraulic radius R=A/p

=0.1963/1.57

=0.125ft

Slop s=drop/length of pipe

=5/15=0.33

As the pipe material is copper, the roughness coefficient c=140

Hazen Williams equation for velocity v=K*c*R^{0.63}*s^{0.54}

Substitute the values k=1.318 ft constant value

V=1.318*140(0.125)^{0.64} *(0.33)^{0.54}

V=26.795ft/s

Flow discharge Q=A*v

=0.1963*26.795=5.25 ft^{3}/s

Therefore, the water flow rate is 26.795 ft/s and flow discharge is 5.25 ft^{3}/s