The present invention refers to a tubing set (12) suitable for use in co-operation with a medical liquid delivery device (10). The tubing set comprises: a delivery tube (68) suitable for supplying a medical liquid or blood to a patient； and a vial gate (24) for the connection of vials (26) containing drugs to be delivered into the medical liquid or blood. The vial gate comprises a delivery lumen (28), suitable for delivering the drug (30) from the vial to the delivery tube； and a vent lumen (32), suitable for providing a replacement fluid (34, 60) from a location (20, 64) inside the tubing set (12) to the inside of the vial in order to replace the delivered drug. The vial gate according to the invention further comprises at least one one-way valve (70, 72) placed along said vent lumen or said delivery lumen.
