Why is a priming device sometimes required in fire pump systems?

• A. To increase discharge pressure.
• B. To dampen vibration.
• C. To create and maintain prime to enable proper pumping, especially when suction conditions could prevent priming.
• D. To monitor temperature.

Answer: (C)

The main idea is that a priming device ensures the pump can start and deliver water by creating and maintaining prime in the suction line. Centrifugal fire pumps must be filled with water so the impeller can develop flow; air in the suction line or leaks can prevent priming and stop the pump from delivering water when needed. A priming device automatically draws water into the pump and expels air until the pump is full, so it can develop the required discharge when suction conditions might otherwise prevent priming. This is especially important when the suction source is remote, the suction line is long or elevated, or there are potential leaks that could introduce air. The other options don’t address the need to fill and maintain the pump with water to achieve proper pumping.