How do you determine the friction loss for a given hose size and flow in a practice scenario?

• A. Estimate by rough guess based on visible water flow.
• B. Friction loss is only a function of hose length, ignore size and fittings.
• C. Only the pump model determines friction loss.
• D. Use the hose friction loss chart or calculator, input hose size and GPM, multiply by the number of 100-foot sections and include number of fittings.

Answer: (D)

Friction loss is the loss of pressure caused by water rubbing against the inside of the hose as it moves, and it depends on how much water is moving (flow) and how big the hose is, plus how long the run is and how many fittings are in the path. To determine it in a practice scenario, use a hose friction loss chart or calculator: choose the hose size and input the flow in GPM, and you’ll get a friction loss value per 100 feet. Then multiply that per-100-foot value by the actual hose length in hundreds of feet (for example, 150 ft becomes 1.5) and add the losses for each fitting used. This approach accounts for diameter, flow, length, and fittings, giving an accurate total friction loss. Guessing is unreliable, friction loss isn’t determined by length alone or by the pump model alone, and you can’t ignore hose size or fittings if you want an correct total.