AUTOMATED DIALYSIS SYSTEM INCLUDING A PISTON AND VACUUM SOURCE

A peritoneal dialysis system includes a hardware unit including a piston and at least one vacuum source; a door connected to the hardware unit, the door including a cavity, the cavity having a diameter; the hardware unit further including a structure positioned opposite the door, the structure defining an aperture; a disposable unit including first and second fluid receiving membranes, the disposable unit disposed between the structure and the door; the at least one vacuum source operable to apply a vacuum to at least one of the first and second membranes of the disposable unit; the piston, at least a portion of which moves through the aperture, in operation contacting one of the membranes, the piston including a piston head having a diameter smaller than the diameter of the cavity in the door; and a dialysis fluid opening enabling dialysis fluid to be pulled in between the first and second membranes.