Piston alternating volumetric pumps designed for use in cleaning units and industrial systems. They can be coupled to various types of motors, either directly or with a flexible joint. The pump body and cover are made of die-cast aluminum alloy. The rear cover may feature an oil drain outlet or incorporate an oil sight glass. Pistons are driven by a crank-connecting rod mechanism. The pump shaft is made of pressed high-strength steel, with oversized friction bearings. Connecting rods are made of bronze, and the pistons are one-piece ceramic. The pump head is made of pressed brass, featuring a double gasket sealing system. Internal components of the pump head may vary depending on the application. Intake and delivery valves are equipped with plugs for easier maintenance. Various regulator valves and accessories can be connected to the pump head.