What is the purpose of priming during pre-run checks?

• A. To calibrate gauges.
• B. To fill the pump with water and remove air to ensure prime.
• C. To start the engine.
• D. To test nozzle materials.

Answer: (B)

Priming is about establishing a water-filled path and removing air so the pump can create suction. In a centrifugal fire pump, air in the pump or suction line breaks the water column and prevents the pump from drawing water from the source. During pre-run checks you prime by filling the pump with water and venting the air until water flows, confirming a solid prime. This setup lets the pump develop suction and deliver water when the engine is started. Calibrating gauges or starting the engine are separate steps, and testing nozzle materials isn’t related to establishing prime.