SU371511A1 - - Google Patents

Description

DETECTING DEVICE FOR GAS CHROMATOGRAPH

one

The invention relates to differential type detectors for gas chromatography, the actions of which are based on the calculation of the values of the thermal conductivity of the pure carrier gas and the mixture of carrier gas with the analyte.

All known types of thermocouple detectors, such as detectors, react not only to the thermal conductivity of the gas, but also to its concealment, since the coefficient of heat transfer from the heated thermosensitive element depends on the magnitude of the velocity. The dependence of the zero signal of the detector on the velocity of the gas significantly impairs its metrological characteristics, which is especially noticeable in the instruments with the temperature of the cubs, at which the gas flow rate of the column changes.

The purpose of the invention is to ensure stability of the mule line. Regardless of fluctuations in the flow rate of the yositel gas while maintaining the sensitivity and inertia of detection and 1com1 of the influence of fluctuations in the flow rate of the carrier gas on the detector signal.

The goal is achieved by the fact that IB with the proposed detecting device, the input of the equalizing channel of a thermal conductivity detector (catarometer) is connected to the input of the measuring (working) channel by a symmetric gas line with an output throttle.

The drawing schematically shows the proposed device.

The device contains a thermal conductivity detector with comparative 1 and 2 working channels, where there are 1 3 sensitive sensing elements vi 4. At the output of the channels, respectively, chokes 5 and 6 are installed. The input of the comparative channel is connected to (the input of the working channel by a symmetrical gas line 7 with an orifice 8 at the output.

Due to the presence of line 7, the gas pressure 1 is always the same at the entrances to the working and comparative channels. Therefore, any changes in the flow rate of both the pure carrier gas and

and eluent from the chromatographic column. Causes pressure changes at the entrances to both channels simultaneously, which leads to a simultaneous and proportional change in the gas velocity IB of both channels. In this case, the Efficiency Factors, which associate pressure changes with speed changes using chokes 5 and 6, can be adjusted so that changes in temperature and electrical resistance of the temperature-sensitive elements included in the adjacent shoulders of the Wheatstone bridge are mutually compensated. The throttle 8 is adjusted so that, for any practically possible flow fluctuations at the entrances to the system, the gas flows IB of both branches of line 7 do not change their direction, which prevents the flow of the eluent into the comparative channel or, if necessary, diluting the eluent with pure gas. the inhabitant of

Shadow Object

A detecting device for a gas-gas chromatograph containing a thermal conductivity detector with a working and equalizing chambers and co-flux supply and output gas channels, characterized in that, in order to compensate for the influence of the carrier gas oscillations on the detector signal, the input channel of the working channel is connected With the inlet of the comparative channel by a symmetric gas line with a reproducible distributor and outlet, three of these are at the outputs of the detector channels also located chokes.

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