The formula used to determine water flow from any solid stream nozzle when the nozzle pressure and tip diameter are known is?

• A. CQ^2L
• B. 29.7 x d^2 x SRofNP
• C. 29.7 x D x SRofNP
• D. 29.7 x d^2 x .434

Answer: (B)

Water flow from a solid stream nozzle depends on both the opening size and the exit speed, which in turn relates to nozzle pressure. The discharge area scales with the square of the diameter, while the exit velocity increases with the square root of the nozzle pressure. When you combine these relationships and use consistent units (diameter in inches, pressure in psi), you get Q = 29.7 × d^2 × √(NP). The constant 29.7 converts the units so the result is in gallons per minute.

So the correct form uses the diameter squared and the square root of nozzle pressure, yielding the GPM value. Options that use the diameter linearly or alter the square root term don’t match the physical relationship or units.