| 摘要 |
<p>A liquid metering and transfer valve assembly (10) for a diluting system which includes a pair of stationary outer valve disc elements (12, 16) sandwiching a central rotatable valve disc element (14). The elements (12, 14, 16) are coaxially aligned and mounted on a spindle (24). One (16) of the outer elements (12, 16) has a first external loop (28) secured thereto, said loop (28) having a precise interior volume. An aspirator probe (26) is secured to the central element (14). The central element (14) carries an axial segmenting passageway (72) having a precise interior volume. A second external loop (86) is secured to the central element (14). The second loop (86) extends outwardly, preferably radially, of said element (14) and has a precise interior volume. Appropriate interior passageways (36, 54, 56, 30) are provided in the outer elements (12, 16) for directing a liquid sample in a continuous path through the valve assembly, the path including the one segmenting passageway (72) and the first and second loops (28, 86). Additional interior passageways (58, 34, 62, 76, 74, 82, 84) are provided for coupling the valve assembly to sources of diluent P2 and to exterior destinations. The central element (14) is rotated to isolate the contents of the segmenting passageway (72) and of the first and the second loops (28, 86) and diluent is fed thereto to drive the isolated contents thereof to said destinations. Only a single loading step is required to obtain three precise volumes of liquid sample. The valve assembly can be rinsed and continuous internal channels (102, 104) are provided for preventing any liquid from reaching the circumferential surfaces 12'', 14'', 16'' of the valve assembly.</p> |
