When operating a deck gun, what is the proper procedure for adjusting the stream without losing prime?

• A. Adjust nozzle after the pump loses prime.
• B. Adjust nozzle while rapidly changing the throttle to maximize flow.
• C. Adjust nozzle while ensuring the pump remains primed; avoid sudden changes that could cause a flow interruption; keep a steady flow.
• D. Turn off the pump before adjusting the nozzle.

Answer: (C)

Maintaining prime while adjusting the deck gun is essential. When the nozzle is altered, the system’s resistance changes, and sudden changes in throttle or nozzle position can cause pressure swings that pull air into the suction or break the prime, interrupting the flow. By keeping the pump primed and making smooth, gradual nozzle adjustments, you preserve a continuous water supply to the deck gun and avoid flow interruptions. Turning off the pump or adjusting after prime is lost would require re-priming and disrupt operation, and trying to “maximize flow” with rapid throttle changes risks losing prime. So, adjust the nozzle calmly while the pump stays primed, keeping a steady flow.