Which of the following is classified as a reciprocating pump?

A piston or plunger pump is classified as a reciprocating pump because it uses a back-and-forth motion to move fluid. In this type of pump, a piston or plunger is driven within a cylinder, creating pressure by displacing a specific volume of fluid with each stroke. This mechanism allows for the controlled transfer of liquids, particularly under high pressure, making it ideal for various applications in water treatment processes where consistent flow rates are necessary.

Reciprocating pumps are known for their ability to handle varying fluid characteristics, including those that may be viscous or contain solids, which enhances their versatility in water treatment. The operation of the piston's movement—either pulling the fluid into the chamber on the suction stroke and then pushing it out during the discharge stroke—creates a positive displacement effect, further distinguishing them from other pump types that rely on kinetic energy to move fluid. Hence, the classification of piston or plunger pumps as reciprocating pumps highlights their unique method of operation compared to centrifugal and other types of pumps that function through different principles.