When priming, water enters the pump primarily because what causes it to flow in?

• A. A Atmospheric pressure forces it into the pump
• B. B The pump pulls the water in from the static source
• C. C The rotating motion of the centrifugal pump creates a vacuum
• D. D Of increase in atmospheric pressure in the pump

Answer: (A)

Priming works because atmospheric pressure on the water surface pushes water into the pump. When the pump starts, it tends to create a low pressure in the suction area, but there isn’t water there yet. The outside air pressure on the source water drives water up into the suction line and into the pump, filling it so the pump can then sustain flow. The other ideas aren’t the main force during priming: the pump isn’t simply pulling in water from a dry source at that moment, the suction doesn’t rely on an internal atmospheric pressure rise, and the movement isn’t driven by a change in pressure inside the pump.