Improvements in the Performance of the Thermal Conductivity Detector

Response characterization of the tritium ionization cross section detector

“…These lower sensitivity limits of 50-100 ppm can be compared with those for a typical TCD (14), used as a continuous monitor, which could be expected to detect a 1-ppm impurity in a helium or hydrogen stream. The linear range of the TCD has been extended by constant filament temperature (15) and constant current (16) operation. Even with these linearity improvements, however, the TCD would appear to be about one order of magnitude less predictable than the MXD, over the full 0-1 molar fraction range, in terms of percentage deviation of predicted response (as span fraction) from actual response.…”

“…where X is the instantaneous molar fraction of this component in the carrier gas (from relation 16), f is the instantaneous (carrier plus sample) detector molar gas flow rate, t is the elapsed time from sample injection, Sm is the molar sample volume and T represents the integration time limits set by an appropriate peak window.…”

“…Valve 8 directed the alternative outlet of valve 7 or the other gas to either a temperature controlled needle valve 16 (Nupro SS-2MA) or to a point D which could be vented or connected to the mixing tee at the inlet of tube 11.…”

“…Then point D was connected to the tee at C, thus blending with hydrogen the gas ex regulator 4. After column 11 break-through of the blend, the detector signals for at least three five-second samples of the same number of consecutive ten-second intervals were used for response data. Throughout this data acquisition period, the diffusion tube hydrogen flow was channelled via valves 7 and 8 to valve 16 which was used as a pressure drop simulator, preset to match the pressure drop of the series connected items 11, 12, 13, 14, and 15 when hydrogen was flowing at the 30 ml/min rate used past the diffusion tube tee.…”

“…Experiments [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Experiments 13-16 used the same experimental arrangements as Nos.…”