What is the condensed Q formula for a 4-inch hoseline?

The condensed Q formula is used to estimate the friction loss in a hoseline based on the flow rate (Q) in hundreds of gallons per minute (GPM). Each hose size has a specific formula associated with it that accounts for the diameter of the hose and the flow rate.

For a 4-inch hoseline, the appropriate formula is FL = Q^2/15, indicating that for every increase in the flow rate, the friction loss increases proportionately to the square of that flow rate divided by 15. This reflects the resistance encountered due to the internal roughness of the hose as water flows through it at varying rates.

Using the correct formula allows for accurate calculations in tactical situations, helping to ensure proper water supply management and effective fireground operations. Understanding these principles is essential for operator safety and efficiency in fire suppression efforts.