Why must priming be completed before charging an attack line?

• A. To ensure water is drawn from the source and the pump remains primed and free of air.
• B. To allow the discharge pressure to rise before charging the line.
• C. To flush residual water from the pump.
• D. To reduce cavitation risk by closing all discharge valves.

Answer: (A)

Priming is about filling the pump and suction line with water to remove air so the pump can develop suction and deliver water. Before you charge an attack line, the pump must be primed so water is being drawn from the source and the pump stays full and free of air. If you charge without priming, air pockets can cause loss of prime and poor or no flow when you try to push water through the line.

That’s why the best choice is that priming ensures water is drawn from the source and the pump remains primed and free of air. The other ideas don’t capture the purpose of priming: pressure rising before charging isn’t the goal, priming isn’t about flushing residual water, and closing discharge valves isn’t how priming works.