In drafting, what is the purpose of priming the pump?

• A. To remove air and fill the pump with water.
• B. To lubricate the impeller
• C. To test gauges
• D. To heat the water

Answer: (A)

Priming a fire pump means filling the pump and its suction line with water and removing the air from that path. In drafting, the pump must develop suction to lift water from the source, and air in the suction line acts like a brake, preventing the pump from creating the negative pressure needed to draw water. When the pump is primed, the suction side becomes a continuous column of water, allowing the impeller to start moving water and build discharge pressure without losing prime. Without priming, the pump would suck in air, cavitate, and fail to deliver water. The priming process often uses a priming device or manual filling to ensure the pump is initially full of water, so it can continue to draw water from the source once it starts. This is about establishing and maintaining a water seal in the pump and suction line, not about lubrication, testing gauges, or heating water.