When using a deck gun, what must be accounted for in determining discharge pressure?

When using a deck gun, what must be accounted for in determining discharge pressure?

• A. Friction losses of the large-diameter hose and elevation
• B. The color of the hose
• C. The weather
• D. The altitude of the operator

Answer: (A)

When a deck gun is used, water travels from the pump through a long large-diameter supply hose to the gun. The pump discharge pressure you set must overcome two main hydraulic losses to deliver the intended nozzle pressure: friction losses in that large-diameter hose, which increase with flow and hose length, and the elevation difference between the pump and the deck gun, which adds head that the pump pressure must push the water up. These losses reduce the pressure available at the nozzle, so you raise the pump discharge pressure by the amount of friction loss plus the elevation head to achieve the desired nozzle pressure. The color of the hose, the weather, or the operator’s altitude don’t affect these hydraulic losses, so they don’t determine discharge pressure in this scenario.

When a deck gun is used, water travels from the pump through a long large-diameter supply hose to the gun. The pump discharge pressure you set must overcome two main hydraulic losses to deliver the intended nozzle pressure: friction losses in that large-diameter hose, which increase with flow and hose length, and the elevation difference between the pump and the deck gun, which adds head that the pump pressure must push the water up. These losses reduce the pressure available at the nozzle, so you raise the pump discharge pressure by the amount of friction loss plus the elevation head to achieve the desired nozzle pressure. The color of the hose, the weather, or the operator’s altitude don’t affect these hydraulic losses, so they don’t determine discharge pressure in this scenario.