A plunger pump designated as 6 x 12 duplex is a two-cylinder pump whose cylinders are 6 inches in diameter with a stroke of 12 inches. A pump with replaceable liners (cylinders) may carry a specifications plate that reads 4.6 x 10. This pump can be fitted with liners and pistons from 4 inches to 6 inches in diameter; its stroke is 10 inches.
