An operator should prime a pump when operating

• A. From a static source
• B. From a pressurized source
• C. From a running engine
• D. From a water tank

Answer: (A)

Priming a pump means filling the pump and its suction line with water to remove air so the pump can develop suction and lift water from the source. When the water source is static, there’s no pressure to push water into the pump, so air would prevent a proper vacuum. Filling the pump with water first eliminates those air pockets and allows the pump to draw water once it starts.

If the source were pressurized, water would push into the pump, so priming isn’t normally needed. The engine’s running status doesn’t define priming—it’s about whether the water supply can push water into the pump. A water tank that isn’t pressurized acts like a static source, so priming would be required there as well.