| 摘要 |
<p>990,264. Valve for gas chromatography apparatus. BECKMAN INSTRUMENTS Inc. June 4, 1962 [June 26, 1961], No. 21456/62. Heading B1L. A gas chromatography apparatus is provided with a slide-valve comprising a housing 10 and a movable block 16, each formed with a plurality of passages so that, by sliding the block in the housing, there are at least three operating positions of the valve. The block is moved by rod 18 so as to (a) obtain a sample of a gas in one position of the block, (b) introduce the sample into the carrier gas stream of the chromatography column 34 in a second position of the block, and (c) connect the column with a source of flushing gas in a third position of the block. In the position of block 16, shown in Fig: 1, passage 46 in the block connects passages 22 and 24 in the housing to allow a stream of the gas to be sampled to flow along line 26. Carrier gas is fed to the chromatography column 34 via line 29 and passage 48 in block 16, and leaves the column via passage 50 in the block, line 38 and a detector (not shown). Movement of block 16 to the position shown in Fig. 2 results in the trapping of a measured volume of the gas in passage 46 and the subsequent delivery of this sample into the carrier gas stream to column 34. Only a momentary interruption of the flow of sample gas in line 26 occurs during the movement of the block, since, in the sample injection position of block 16, the two sections of line 26 are connected by passage 54. The connection between column 34 and line 38 in this second position of block 16 is afforded by passage 48. On moving block 16 back to the position shown in Fig. 3, the column 34 is connected to a source of flushing gas via passage 56 in block 16 and line 42, the flushing gas being vented from the column via passage 58 and line 44. The block 16 may be made of polytetrafluorethylene. A valve is also described, comprising a block containing eleven separate passages, which can be slid into five separate positions in the valve housing, so as to perform all the valving operations normally required in the operation of a gas chromatography apparatus comprising two columns.</p> |
