What is the method for estimating friction loss for a 2.5-inch attack line running at 150 GPM over 200 feet?

• A. Use a friction loss table or formula for 2.5" hose at 150 GPM to estimate per-100 ft loss; multiply by 200 ft; add any losses from fittings; use in pump calculations.
• B. Multiply GPM by length.
• C. Friction loss is the same regardless of length.
• D. Ignore friction loss for 200 ft.

Answer: (A)

Friction loss in a hose is estimated using a per-100-foot value for the hose size and flow, then scaled to the actual run length and added to fittings losses to use in pump calculations. For a 2.5-inch hose at 150 GPM, you look up the friction loss per 100 feet, multiply by the number of hundred-foot sections in the hose lay (200 ft equals two sections), and then add losses from fittings and any appliance losses. This total is what you factor into the pump discharge calculations to determine nozzle pressure or required pump output.

This approach is correct because friction loss depends on both the hose diameter and the flow rate, and it scales with length. Simply multiplying GPM by length would not account for the diameter-dependent resistance and is not how friction loss is estimated. Ignoring friction loss or treating it as the same regardless of length would lead to incorrect pump settings.