Flow Rate Vs. Pipe Size

Updated April 17, 2017

Properly pumping water through pipelines is an essential part of the make-up of modern society. It is important to know how much water can be transported and a key factor in this is the size of the pipe used.

Flow Rate

Flow rate is a measurement of the volume of water that flows through a pipe in a given amount of time. Generally, flow rate is recorded in terms of gallons per minute.

Effects of Pipe Size

If the pressure behind water flow in a pipe is kept constant, the size of the pipe will directly affect the flow rate. If the diameter of the pipe is increased, the flow rate will decrease. Also, If the length of the pipe is increased, the flow rate will decrease due to friction.


Flow rate is also affected by change in a pipe's elevation, bends or curves in a pipe, and the roughness of a pipe's surface. So while the relationship between pipe size and flow rate is constant, size is not necessarily the deciding factor in a pipe's flow rate.

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About the Author

Owen Rogers has been a full-time English student since 2008 at the State University of New York at Geneseo. This is his first experience writing in a professional sense.