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In the use of gas chromatographs, air has many uses: on the one hand, FID, FPD and NPD require air as the combustion gas; in addition, when the gas chromatograph is equipped with an automatic six-way valve, etc., air can be used. As a driving gas for switching the driving switching device; in addition, when using a detector such as FID for detection, some researchers use air as a makeup gas, with some unexpected results.
In general, the air-generating workflow is that the ambient air is compressed by the compressor into the gas storage tank gas chromatography vials, and then passed through the purifier through the gas storage tank, and then input into the gas chromatograph through the pressure regulating valve. Among them, the gas storage tank is used to store the gas and maintain a certain pressure; at the same time, the gas storage tank can prevent the air output fluctuation caused by the water discharge timing of the water discharge port; the pressure sensor on the gas storage tank can monitor the pressure of the gas storage tank, To open and close the compressor, exhaust and other functions; purifiers generally use silica gel to initially remove water, molecular sieves to remove water, activated carbon to remove hydrocarbons; regulator valve can regulate the output pressure of air compressors.
In the actual use of the air generator, for the constant material analysis, the conventional oil-free air generator can meet the requirements, but for the following reasons, the analysis of trace components, etc. can not meet the demand:
(1) The initial gas source of the air generator is the laboratory or the periphery of the laboratory. This part of the air source may contain more organic compounds, so the quality of the compressed air produced does not meet the needs of the laboratory;
(2) The air compressor is nominally oil-free gas chromatography vials , but in practice a conventional compressor is used, and the purification device at the rear of the compressor cannot completely remove the oil mist therein;
In order to solve the above problems, a common solution is to install an oil mist filter at the inlet of the air compressor to remove oil mist from the air source of the compressor; and to install a hydrocarbon removal device & zero at the outlet of the air compressor. Class air generator; or purchase a pure oil-free air source.
The zero-stage air generator/hydrocarbon removal unit is a device for purifying air. Catalytic cracking of hydrocarbons in compressed air in a catalytic converter containing a platinum-palladium carrier converts hydrocarbons into carbon dioxide and water vapor. , thereby producing zero-order air of less than 0.1 ppm of hydrocarbons.
In actual use, how to choose the air generator should be determined according to the place where the air generator is used (assisted gas or driving gas), and the air generator should be selected according to the air usage of the instrument; According to the project carried out by the instrument (determination of oxygen peaks in trace components or non-methane total hydrocarbons, etc.), it is necessary to install a zero-stage air generator gas chromatography vials.
This is the end of the introduction of Air generator selection in gas chromatograph. I hope it can help you.