What is the minimum nozzle inlet pressure for a combination fog and straight stream nozzle?

What is the minimum nozzle inlet pressure for a combination fog and straight stream nozzle?

• A. 50 psi
• B. 65 psi
• C. 70 psi
• D. 75 psi

Answer: (B)

When a nozzle is designed to switch between fog and straight-stream modes, it needs a baseline amount of energy at the inlet to reliably produce both patterns. That baseline is 65 psi. At this pressure, the nozzle can atomize water into a usable fog and still deliver a controllable straight stream for longer reach, even after accounting for friction losses in hoses and fittings typical of standpipe runs. Pressures lower than 65 psi often fail to produce consistent fog quality or a dependable straight stream, while higher pressures simply exceed the minimum needed to meet the requirement.

When a nozzle is designed to switch between fog and straight-stream modes, it needs a baseline amount of energy at the inlet to reliably produce both patterns. That baseline is 65 psi. At this pressure, the nozzle can atomize water into a usable fog and still deliver a controllable straight stream for longer reach, even after accounting for friction losses in hoses and fittings typical of standpipe runs. Pressures lower than 65 psi often fail to produce consistent fog quality or a dependable straight stream, while higher pressures simply exceed the minimum needed to meet the requirement.