How is friction loss calculated for hose and fittings?

• A. Friction loss is a fixed value for each hose regardless of flow.
• B. Friction loss should be guessed based on experience.
• C. Use published friction loss charts for the specific hose size and flow; multiply per 100 ft by the actual length and include fittings’ losses.
• D. Friction loss is only dependent on water temperature.

Answer: (C)

Friction loss is a function of the flow rate through a specific hose size, not a fixed value. To calculate it, use the published friction loss data for the hose size at the expected discharge. Find the friction loss per 100 ft at that flow, multiply by the actual hose length, and then add the losses from all fittings, adapters, and appliances in the line. This combination gives the total friction loss you must overcome to reach the nozzle.

Temperature isn’t what drives friction loss; it’s the combination of flow and hose diameter, plus any fittings in the path. Using published charts ensures you’re applying tested, hose-specific values rather than guessing.