Which statement correctly identifies the priming pump type?

• A. Centrifugal
• B. Rotary gear
• C. Piston
• D. Diaphragm

Answer: (B)

Priming the pump means pulling water into the pump by creating a vacuum in the suction line so air is expelled and water can flow into the pump. A rotary gear priming pump fits this role best because its positive-displacement action traps and moves a fixed amount of fluid with each turn, which effectively pulls air out of the suction line and starts water flow into the main pump. This makes it reliable and compact for priming on fire apparatus.

Centrifugal pumps, by contrast, rely on water in the impeller to generate flow and aren’t used as priming devices on their own. Piston and diaphragm priming options exist in other systems, but on typical apparatus the gear-type priming pump is the standard, efficient choice for initiating the prime.