What formula is used to calculate friction loss (FL) in a hose?

The formula for calculating friction loss (FL) in a hose is represented as FL = C × Q² × L, where C is the friction loss coefficient, Q is the flow rate in hundreds of gallons per minute, and L is the length of the hose in hundreds of feet. This formula is critical for firefighters as it helps determine how much pressure is lost due to friction when water flows through the hose.

In this equation, the reason for the squared relationship with flow (Q²) is significant because friction loss increases with the square of the flow rate. This means that even a small increase in the flow rate can lead to a substantial increase in friction loss, making it crucial for engineers to understand how to calculate it accurately to ensure that adequate pressure is maintained for effective firefighting operations.

The inclusion of the hose length (L) further contextualizes how the duration of the water movement through the hose impacts the overall friction loss. Longer hoses create more resistance, thus increasing the friction loss directly in proportion to their length.

This combined approach in the formula allows firefighters and engineers to take a systematic approach to ensure that when water is delivered through hoses, the pressure drop due to friction does not compromise firefighting efforts.