Patent ID: 8628304

Claim:
A multi-stage membrane suction pump comprising at least three pump chambers, each including a fluid inlet having at least one inlet valve and a fluid outlet having at least one outlet valve, as well as a suction line connecting the fluid inlets of the pump chambers, with successive ones of the pump chambers each being connected to each other via at least one connection line such that, upon at least one of reaching or exceeding a differential pressure in the suction line, an operation of the pump changes from a parallel operation of the pump chambers to at least also a serial operation of said pump chambers, at least one check valve, open to a downstream pump stage, is interposed in an inlet area and in an outlet area of the at least one connection line, and the check valves provided in the inlet area and in the outlet area of each connection line are embodied smaller in reference to the inlet valves and the outlet valves of the pump chambers, one line section of each of the connection lines, open towards the adjacent pump chamber, being allocated to said check valves, has a smaller clear cross-section in reference to the inlet valves and the outlet valves, and the at least one inlet valve, the at least one outlet valve, and two of the check valves open in each of the pump chambers located between the chamber of a first one of the pump stages and the chamber of a last one of the pump stages.