A single-piston reciprocating pump has a 6 inch diameter piston with a 6 inch stroke. It makes 16 discharge strokes per minute. The pumping rate is approximately how many gallons per minute?

A single-piston reciprocating pump has a 6 inch diameter piston with a 6 inch stroke. It makes 16 discharge strokes per minute. The pumping rate is approximately how many gallons per minute?

• A. 8 GPM
• B. 12 GPM
• C. 24 GPM
• D. 6 GPM

Answer: (B)

Flow from a piston pump is the volume displaced per stroke times the number of discharge strokes per minute, with a conversion from cubic inches to gallons. Piston diameter is 6 inches, so radius is 3 inches. Area = πr^2 = 9π square inches. Stroke length is 6 inches, so volume displaced per stroke = area × stroke = 9π × 6 = 54π cubic inches. With 16 discharge strokes per minute, the volume per minute = 54π × 16 = 864π ≈ 2714.34 cubic inches per minute. Since 1 gallon = 231 cubic inches, the flow rate = 2714.34 / 231 ≈ 11.75 GPM, which rounds to about 12 GPM.

Flow from a piston pump is the volume displaced per stroke times the number of discharge strokes per minute, with a conversion from cubic inches to gallons.

Piston diameter is 6 inches, so radius is 3 inches. Area = πr^2 = 9π square inches. Stroke length is 6 inches, so volume displaced per stroke = area × stroke = 9π × 6 = 54π cubic inches.

With 16 discharge strokes per minute, the volume per minute = 54π × 16 = 864π ≈ 2714.34 cubic inches per minute. Since 1 gallon = 231 cubic inches, the flow rate = 2714.34 / 231 ≈ 11.75 GPM, which rounds to about 12 GPM.