Which topic concerns calculating the appropriate pipe diameter to achieve desired flow with acceptable velocity?

• A. Velocity
• B. Pipe Sizing
• C. Friction Factor
• D. Water Harvesting

Answer: (B)

Pipe sizing is the process of selecting a diameter that can carry the required flow while keeping the velocity within practical limits. This relies on the continuity principle Q = vA, so for a given flow rate you choose the bore area (and thus diameter) to set the velocity at an acceptable level. Too-small a pipe makes velocity, and thus friction losses and pumping energy, unnecessarily high. Too-large a pipe wastes material and can cause other issues without added benefit. In practice you estimate head losses for different diameters using standard hydraulic equations or tables (such as Hazen-Williams or Darcy-Weisbach) and pick the diameter that meets both the flow and velocity targets. Velocity describes how fast water moves, while friction factor and related loss calculations inform energy requirements, but the core task here is selecting the pipe size to achieve the desired balance of flow and velocity. Water harvesting, by contrast, relates to collecting rainfall and isn’t about determining pipe diameter for flow.