Pumps commonly used as priming pumps are known as which type?

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

Answer: (B)

Priming pumps must create a seal and establish suction to pull water into the pump and fill the main unit. A rotary gear pump does this best because it’s a positive displacement device that traps a fixed amount of water between the gears and the housing. As the gears rotate, a low-pressure area forms on the suction side, drawing in water and expelling air until the pump is full. Its simple, compact design and reliable self-priming action make it a common choice for priming on portable pumps. Other pump types rely more on velocity or different priming dynamics, so they’re less commonly used as dedicated priming pumps.