Using the hand method, friction loss for 100 ft of 2.5 inch hose at 300 gpm is approximately:

Using the hand method, friction loss for 100 ft of 2.5 inch hose at 300 gpm is approximately:

• A. 12 psi
• B. 18 psi
• C. 24 psi
• D. 30 psi

Answer: (B)

Friction loss in a handline is a function of how much water you’re flowing and the hose size, and the hand method uses a simple table to estimate this quickly per 100 feet. For a 2.5-inch hose carrying about 300 gpm, the quick-reference table gives about 18 psi of friction loss for every 100 feet of hose. Therefore, a 100-foot run loses roughly 18 psi to friction, which is why that option is the best choice. If the line were longer, you’d scale linearly (for example, 200 feet would be about 36 psi). Keep in mind this is an estimate; actual friction loss can vary with hose condition, fittings, and other real-world factors, but 18 psi per 100 ft is the standard hand-method figure for this combination of hose size and flow.

Friction loss in a handline is a function of how much water you’re flowing and the hose size, and the hand method uses a simple table to estimate this quickly per 100 feet. For a 2.5-inch hose carrying about 300 gpm, the quick-reference table gives about 18 psi of friction loss for every 100 feet of hose. Therefore, a 100-foot run loses roughly 18 psi to friction, which is why that option is the best choice. If the line were longer, you’d scale linearly (for example, 200 feet would be about 36 psi). Keep in mind this is an estimate; actual friction loss can vary with hose condition, fittings, and other real-world factors, but 18 psi per 100 ft is the standard hand-method figure for this combination of hose size and flow.