Piston plunger pumps.

These are valve pumps based in their operation on a series of check valves located at the inlet and outlet, controlling the flow. The pumps have compartments/chambers in which fluid is drawn in and out by the movement of the piston. They are manufactured in single or multi-piston versions. They are driven from the motor via a flat belt or gear set. They are still used in technological installations of older branches of the refinery.