Which statement concerning automatic adjusting fog nozzles is true?

Which statement concerning automatic adjusting fog nozzles is true?

• A. They automatically shut off when pressure drops below a threshold
• B. They only work at fixed flow rates
• C. The amount of water flowing through the nozzle is adjusted to maintain the rated pressure
• D. They reduce water flow to save energy

Answer: (C)

Automatic adjusting fog nozzles regulate the discharge to keep the nozzle at a designed pressure even as supply pressure changes along the hose. This means the nozzle automatically meters water flow: when upstream pressure goes up, it reduces flow to hold the rated nozzle pressure; when upstream pressure drops, it increases flow to maintain that same pressure. Keeping the nozzle pressure constant preserves the intended fog pattern, reach, and cooling effectiveness during interior work, regardless of variations in supply or line friction. So the statement describing the nozzle as adjusting the water flow to maintain the rated pressure is the true, practical behavior. They don’t simply shut off at low pressure, they aren’t fixed-flow devices, and their primary purpose isn’t energy saving but maintaining a reliable, effective discharge pattern.

Automatic adjusting fog nozzles regulate the discharge to keep the nozzle at a designed pressure even as supply pressure changes along the hose. This means the nozzle automatically meters water flow: when upstream pressure goes up, it reduces flow to hold the rated nozzle pressure; when upstream pressure drops, it increases flow to maintain that same pressure. Keeping the nozzle pressure constant preserves the intended fog pattern, reach, and cooling effectiveness during interior work, regardless of variations in supply or line friction.

So the statement describing the nozzle as adjusting the water flow to maintain the rated pressure is the true, practical behavior. They don’t simply shut off at low pressure, they aren’t fixed-flow devices, and their primary purpose isn’t energy saving but maintaining a reliable, effective discharge pattern.