Abstract: A gas rinsing stopper includes a stopper member having therethrough an axial gas passage, a mounting fixture extending into a first end of the gas passage, a gas feed opening at a second end of the passage, and a gas supply line extending into the gas passage. A seal member is positioned within the gas passage and forms a gas tight seal separating the gas passage into a first section including the mounting fixture and a second section leading to the gas feed opening. The gas supply line opens into the second section of the gas passage, such that rinsing gas supplied through the gas supply line is isolated from the first section of the gas passage. This prevents the supply of rinsing gas from creating a reduced pressure at the first end of the gas passage, and thereby prevents atmospheric air from being drawn into the gas passage and mixing with the rinsing gas.