Single Action (Pump): A reciprocating pump design that produces a pressure differential across the pump in only one direction of drive rod motion.
Single action pumps only use a single pump chamber per drive rod. They are only capable of producing pressure while the plunger or piston is moving into the pump chamber. Single action pumps are common in all sizes of reciprocating plunger and piston pumps.
Single Action Pump Characteristics
Single action pumps have design advantages and disadvantages over dual-acting designs. A single action or double action pump should be selected based on system requirements and design.
The flow of a single action pump will have more variation in the flow compared to a double-action pump of the same size. Each drive rod is producing a pressure differential across the pump through half of the drive shaft’s rotation. The unsteady flow results in larger pressure waves. Attention to surrounding system design, or the addition of a pulsation dampener, might be more important for single action, and all reciprocating pumps. Especially in smaller sizes, including simplex, duplex, and triplex pump sizes.
