| 摘要 |
<p>A transfer device for withdrawal of aliquots from a container of bulk solution is provided with a body having a tapered chamber, a first passage venting the smaller end of the chamber to the surrounding air, a second passage communicating at one end with the larger end of the chamber, and a third passage having one end for withdrawal of fluid therefrom. A tapered valve element is received within the chamber for movement between first and second conditions in response to changes in the presence differential between the first and second passages. The first condition provides a fluid seal between the first and second passages by engagement of the valve element with the walls of the chamber for pressures within the second passage greater than that within the first passage, and the second condition provides a fluid path from the first passage to the second passage for pressures within the second passage somewhat less than that within the first passage. The device further includes structure placing the other ends of the second and third passages in commuication with the interior of the container of bulk solution, such that a path is provided for air to be drawn into the container when aliquots of solution are withdrawn from the container through the third passage.</p> |
