How do double-acting piston pumps reduce changes in pumping rate?

In a standard reciprocating piston pump, the pumping rate fluctuates because it varies from zero at the point of directional change to a maximum at the midpoint of the stroke.

Double-acting piston pumps reduce these changes in the pumping rate by utilizing both sides of the piston to move fluid during each cycle of operation. By engaging both sides of the piston, the pump ensures that fluid is being displaced more continuously throughout the stroke, thereby smoothing out the fluctuations that occur in single-acting designs. Further reductions in these rate variations can be achieved by incorporating more than one cylinder into the system.1