Which combination represents the two core components of pipe sizing methods?

• A. Velocity
• B. Friction Factor
• C. Velocity and Friction Factor
• D. Pipe Sizing

Answer: (C)

In pipe sizing, you must balance how fast the water will move with how much resistance the pipe walls create to that flow. The two pieces you need are velocity and friction factor. Velocity tells you the flow speed inside the pipe for the given diameter, which affects things like erosion, noise, and practical delivery. Friction factor captures the pipe’s resistance to flow, depending on roughness and flow regime, and it drives the head loss the system will experience over a given length. Using both together—through the relevant head-loss equations—lets you pick a diameter that meets the required flow while keeping losses and velocities within acceptable limits. If you only consider velocity, you’d miss whether the pipe will drop too much pressure; if you only consider friction factor, you’d miss whether the pipe can carry the needed volume. That’s why velocity and friction factor represent the two essential components.