Positive Displacement Pumps have two main types of pumps: Piston pump and which?

• A. Rotary pump
• B. Centrifugal pump
• C. Gear pump
• D. Diaphragm pump

Answer: (A)

Positive displacement pumps move a fixed volume of fluid with each operation, and they fall into two broad families: reciprocating and rotary. A piston pump is an example of the reciprocating type, where the piston changes the chamber volume to draw in and push out fluid. The other main type is rotary pumps, which trap fluid in cavities between rotating parts and move it to the discharge with each rotation, providing a continuous, steady flow and typically handling viscous fluids well. So, the pair with the piston pump is the rotary pump. Centrifugal pumps are not positive-displacement, since they add energy through an impeller and rely on system resistance for flow. A gear pump is a specific rotary positive-displacement pump, and a diaphragm pump is a reciprocating positive-displacement pump, but the broad other main category alongside the piston pump is the rotary pump.