Which pump uses the reciprocating action of a piston to move fluid, and is good for high pressure but low flow?

• A. Vane Pump
• B. Gear Pump
• C. Rotary Pump
• D. Reciprocating Pump

Answer: (D)

A pump that uses the back-and-forth motion of a piston inside a cylinder is a reciprocating pump. This type is a positive-displacement device: each piston stroke moves a fixed volume of fluid, so it can develop high pressures even when the overall flow is relatively small. The flow is often pulsatile, but the pressure achievable per stroke is high, which is ideal when you need high pressure with low flow. In contrast, vane, gear, and other rotary pumps move fluid with rotating parts and tend to deliver smoother, higher-volume flow at moderate to high pressures, not the same combination of high pressure with inherently low flow that a piston-based reciprocating pump provides.