How do you estimate friction loss using hose charts?

• A. Multiply the total hose length by the friction loss per 100 ft.
• B. Friction loss per 100 ft is constant for all GPM.
• C. Friction loss is independent of hose size.
• D. Use the chart to find friction loss per 100 ft for the given hose size and GPM, then multiply by the hose length in hundreds of feet to get total friction loss.

Answer: (D)

Friction loss depends on how fast water is flowing and the hose size, and hose charts give a friction loss per 100 ft for a specific size at a given GPM. To estimate the total friction loss for a run, look up the friction loss per 100 ft for that hose size and your GPM, then multiply by the length expressed in hundreds of feet. For example, if you have 200 ft of hose and the chart shows 15 psi per 100 ft at your GPM, multiply 15 by 2 to get 30 psi total. This method uses the chart’s per-100-ft value and scales it by the actual length. The other ideas fail because they either assume a constant value independent of GPM and size or ignore the need to convert the length into hundreds of feet.