Friction loss is always expressed in which unit?

Friction loss is always expressed in which unit?

• A. kPa per meter
• B. psi per meter
• C. pounds per square inch per foot
• D. psi per foot

Answer: (D)

Friction loss is a pressure drop that builds up along the length of the pipe, so it’s expressed as pressure loss per unit length. In sprinkler practice using US customary units, pressure is measured in psi, so the most straightforward way to show this rate is as psi per unit length. The direct form, psi per foot, communicates exactly how much pressure is lost for each foot of pipe. A metric form like kPa per meter would be used only if you’re working in metric units, and the equivalent of psi per foot (pounds per square inch per foot) is the same idea written differently. Therefore psi per foot is the standard expression in this context.

Friction loss is a pressure drop that builds up along the length of the pipe, so it’s expressed as pressure loss per unit length. In sprinkler practice using US customary units, pressure is measured in psi, so the most straightforward way to show this rate is as psi per unit length. The direct form, psi per foot, communicates exactly how much pressure is lost for each foot of pipe. A metric form like kPa per meter would be used only if you’re working in metric units, and the equivalent of psi per foot (pounds per square inch per foot) is the same idea written differently. Therefore psi per foot is the standard expression in this context.