How to Calculate Gear Pump Displacement

A gear pump's displacement occurs when its gears turn.

As its name suggests, a gear pump displaces a fluid by turning a pair of gears. The gears' teeth lock into one another, and their rotation forces the pump's fluid through an outlet. The rate of fluid displacement through this outlet depends on two factors. A faster fluid velocity leads to a greater volume displacement. A larger cross-sectional area of the pump leads to a similarly increased volume displacement.

Instructions

1. Multiply the the fluid's velocity in feet per second by 720. If the velocity is 0.0125: 0.0125 x 720 = 9 inches per minute.

2. Square the pump's cross-sectional area, in square inches. If its area is 25 square inches: 25 x 25 = 625.

3. Multiply the answer from Step 1 by the answer to step 2: 9 x 625 = 5,625.

4. Divide your answer by 231: 5,625 / 231 = 24.4. This answer is the pump's displacement in gallons per minute.

References

• Iowa State University: Pump and Motor Basic Principles
• North Carolina State University: Hydraulics