| 摘要 |
1322438 Chromatography HYDRONAUTICS-ISRAEL Ltd 18 Aug 1971 [19 Aug 1970 28 April 1971] 38754/71 Heading B1X [Also in Division Gl] A sampling valve for gas analysis apparatus, in particular a gas chromatography column 30, using a carrier gas, such as helium supplied on line 28 or lines 52 and 54, and an associated ionisation detector, includes a housing 20 or 20', a part 34 or 34' having a bore 36, 38 or 64 which may, by rotation of the part 34 or 34'; be communicated selectively either with an ambient atmosphere via housing apertures 22, 24 or 56, 58 or with a gas detection device via aperture 26 and 62, adsorbing means such as a platinum gauze ball 40 or 40', or wire (248) for adsorbing a preselected substance from the atmosphere located or locatable within the bore, and means to heat the adsorbing means when the bore is communicated with the aperture 26 or 62 such that the substance is desorbed from the platinum and passed to the detection device. The heating means may be an oven 46, as in Fig. 1, or electrical circuitry, as in Fig. 8 (not shown) and including a storage capacitor (74), adapted to pass current through the platinum ball or wire. If an oven is used, a ball 40 is projected from a holder 42 by electromagnet 44 into the bore 36, 38 to start a sampling cycle, the ball falling back into the holder to be degassed in the oven to complete the cycle; but by using direct heating circuitry the adsorbing means may be housed within the bore 64 permanently. Four embodiments of valve are described, some including modifications (e.g. aperture 60 and additional bore 66) for purging the valve before desorption and for maintaining the supply of carrier gas to the column 30 substantially constant. The cycle of sampling may be automated, e.g. by applying circuitry as in Figs. 13, 14 or 21 (not shown), and in the case where a ball 40 is projected into the valve bore, movement of the ball past a photoelectric cell (130) is used to initiate and stop the cycle. |
