What formula is used to determine water flow from any solid stream nozzle?

The formula used to determine water flow from any solid stream nozzle is defined as Q = 29.7 x d² x NP, where Q represents the flow in gallons per minute (GPM), d represents the diameter of the nozzle in inches, and NP represents the nozzle pressure in pounds per square inch (PSI). This formula is derived from the principles of fluid dynamics and ensures that flow calculations for nozzles take into account both the size of the nozzle opening and the pressure driving the water through it.

The constant 29.7 is a factor used to convert the mathematical calculations into GPM, reflecting the relationship between diameter, pressure, and flow. By squaring the diameter, the formula emphasizes that small increases in diameter can significantly alter the flow rate, since flow increases with the area of the nozzle opening. Meanwhile, including the nozzle pressure accounts for the force propelling the water.

Understanding this formula is critical for fire apparatus operators, as it helps them select the appropriate equipment and settings to ensure effective water delivery during firefighting operations.