The formula .067 d^2 x / NP is used to estimate which quantity for a solid stream nozzle?

The formula .067 d^2 x / NP is used to estimate which quantity for a solid stream nozzle?

• A. Flow of water in litres per minute
• B. Pressure drop across a valve
• C. Foam concentrate flow
• D. Time to prime

Answer: (D)

Priming time for a solid stream nozzle is what this formula estimates. The time grows with the square of the nozzle diameter, so a larger nozzle means more water and air must be moved to fill the suction line, lengthening the prime. It decreases as nozzle pressure increases, since higher pressure pushes water into the line faster and clears air more quickly. The x factor is a constant tied to the specific pump setup and drafting conditions, and the 0.067 is a calibration coefficient to make the estimate fit practical measurements. Because of these relationships, the expression aligns with what you’d expect in the field: bigger nozzles slow priming, higher pressure speeds it up. Other options describe different quantities that don’t follow this d^2/NP relationship.

Priming time for a solid stream nozzle is what this formula estimates. The time grows with the square of the nozzle diameter, so a larger nozzle means more water and air must be moved to fill the suction line, lengthening the prime. It decreases as nozzle pressure increases, since higher pressure pushes water into the line faster and clears air more quickly. The x factor is a constant tied to the specific pump setup and drafting conditions, and the 0.067 is a calibration coefficient to make the estimate fit practical measurements. Because of these relationships, the expression aligns with what you’d expect in the field: bigger nozzles slow priming, higher pressure speeds it up. Other options describe different quantities that don’t follow this d^2/NP relationship.