What is the approximate friction loss when water flows through 100 feet of a 4" hose at 500 gpm?

To determine the friction loss for water flowing through a 4-inch hose at a flow rate of 500 gallons per minute (gpm), we can reference established friction loss formulas that consider both the diameter of the hose and the flow rate.

Friction loss in hoses is typically calculated using the formula that takes into account the flow rate and the size of the hose. For a 4-inch diameter hose, it is known that friction loss can be approximated at certain flow rates. At a flow rate of approximately 500 gpm, the friction loss tends to fall around 5 psi for every 100 feet of hose. This relationship is well documented in fire service guidelines and hydraulic calculations for hoses.

Understanding that friction loss increases with both the length of the hose and the rate of flow, knowing that 500 gpm is a significant flow rate gives us confidence that friction loss will be notable, but not excessively high for a 4-inch diameter hose. Specifically, for this application at 500 gpm over 100 feet, the figure of 5 psi aligns closely with the calculations and empirical data sourced from hydraulic tables used in fire service practice.

Thus, the correct answer is 5 psi, as it accurately reflects the friction loss experienced