The invention is related to an apparatus comprising: a valve body comprising two inlet openings, one outlet opening and a central space connecting the inlet openings and the outlet opening, and a spherical element movably contained inside the central space configured for translatory movement and configured to seal either the first inlet opening or the second inlet opening, wherein each of the inlet openings are configured for fluid communication with a first reservoir and with a second reservoir and wherein the outlet opening is configured for fluid connection with a septum. This apparatus solves the object to make the exchange of used parts including the valve construction less complex. A further object of the invention is to make the exchange easier to handle. The invention is also related to a medical device comprising a dispense interface and an apparatus of the afore-mentioned type.