| 摘要 |
A hollow container defining a sample chamber is formed of at least two parts (30, 40) which fit together and have apertures (34, 36; 44, 46) therein. One of the parts (40) is displaceable relative to the other part (30) between a first relative disposition of the parts in which the apertures are open so as to provide a clear path for air to pass through the container and a second relative disposition of the parts in which the apertures are closed so that there is no path for air to pass through and a volume of air is trapped in the chamber. In one version the part (40) is axially moveable relative to the other part (30). In another version where the parts are tubular one of the parts is rotatable relative to the other. In other versions the apertures are in respective end closures and end caps located thereover and the end caps are rotatable to align the apertures and open the chamber for air to pass through. In other versions, one of the parts is pivotable or bendable relative to the other to open or close the respective apertures. In yet other versions one part is rotatable on an axis transverse to the axis of the other part to open or close the respective apertures. |
