Friction loss in pipe is determined by flow rate,
pipe diameter, age, and the pipe material.
Appendix X provides values for several pipe materials. An
example in reading the tables shows that a standard
1-in. steel pipe which has a flow rate of 10.1 gpm
will cause a pressure drop of 5.1 psi for every 100 ft.
of length. A plastic pipe under the same conditions
will have a pressure drop of 2.7 psi, and a rubber
hose will have a drop of 3.38 psi. Other conditions,
such as price, placement, and application, also
determine the proper choice for a given situation.
Additional energy losses occur at fittings such as
valves, elbows, tees, unions, etc.