Roughness in a commercial pipe can be categorized in two ways: absolute roughness and relative roughness. The roughness can be calculated by dividing its roughness by the internal diameter. The number obtained from doing this is used to calculate the pipe friction factor as will be discussed below. Being able to calculate the roughness of a pipe will help you know the ability for fluids to flow smoothly through the pipe. Also, knowing how efficient your pipes are will help you know whether they are doing their job as well as they should be doing.

Commercial Pipes' Head Loss

The head loss is the amount of pressure lost as a result of friction in the pipe. The friction is created by the roughness of the pipe. The rougher the pipe, the more the friction with the liquid flowing through. However, the head loss can also be affected by the size of the pipe's diameter (more loss for a smaller diameter as a smaller diameter means more of the liquid is touching the rough walls), the elevation of the pipe (comparing one end to the other), and the length of the pipe. If there are any extra valves along the pipe line, their value must be calculated separately.

Darcy Weisbach Formula

This formula is often used by hydraulic engineers to calculate the loss in commercial pipes. However, following the formula can help anyone understand how efficient their pipes really are. Here is the equation along with a key to understand what is substituted where. The measurements are in the metric system.

hf =f (L/D) x (v ^2/2g)

hf = head loss in meters

f = friction factor

L= length of pipe work in meters

D= the diameter of the pipe's inside in meters

v= velocity of the fluid in meters per second

g= acceleration due to gravity in meters per second squared

Some of these factors can be found easier than others. The hardest and most debated part of this formula is the friction factor. Before, this formula was almost never used due to the difficulty in calculating the friction factor. However, due to the Moody Chart, you can easily find your friction factor and be able to complete the formula to calculate your head loss.

Once you have calculated the head loss, you can experiment with different numbers to see what must be reduced to lower the head loss. Once you are able to lower the head loss, you will be able to have more efficient commercial pipes.