The process of gas chromatography can vary with the object analyzed and the identifier used, but the basic process is still the same, which can be represented by a block diagram, as shown in the following figure:
(1) Air source. High-pressure steel cylinders are mostly used as the carrier gas storage, which is filled with high-pressure high-purity gas (about 15MPa when full). Special attention should be paid to safety during use. It is equipped with a pressure reducing valve to decompress the high-pressure gas into a low-pressure gas, generally reduced to about 0.3MPa, and the maximum should not exceed 0.5MPa. The pressure reducing valve and the nozzle of the high-pressure cylinder must be closely matched to avoid air leakage or accidents. The decompressed low-pressure carrier gas enters the purification tube for purification to purify the carrier gas and remove moisture. The purification tube can be made of metal, plastic, plexiglass and other materials into a cylindrical shape, and can be filled with purifying agents such as 5A molecular sieve, color-changing silica gel, and activated carbon as required. After the decontamination agent has been used for a period of time, the decontamination agent should be replaced or reactivated and continue to be used. The purified carrier gas requires a stable flow rate. A pressure-stabilizing valve can be used to stabilize the pre-column pressure, and a pressure-stabilizing valve or a needle valve can also be used to precisely adjust the flow rate. The determination of its flow rate is usually indicated by a rotameter, and the real flow rate is corrected by a soap film flowmeter connected to the column.
(2) Injection. The injector is the element that passes the sample through the chromatographic column, and the vaporization chamber is the device that instantaneously vaporizes the liquid or solid sample into vapor. Common injection tools are quantitative valves or syringes. It is injected from the injection port, and the silicone rubber gasket of the injection port should be replaced in time to prevent air leakage.
(3) Chromatographic column. It can be said to be the heart of the chromatograph, and its role is to separate the mixture into single components. There are packed columns, hollow columns and capillary columns. At present, the power system generally uses packed columns, which are made of glass, stainless steel or copper, filled with stationary phase or coated with stationary liquid, and the tube shape is mostly spiral or U-shaped. If you can find an ideal chromatographic column according to the needs of production or scientific research in your work, you can say that you have found a new analytical method. A chromatograph can separate different substances to meet the needs of production as long as the chromatographic column and its operating conditions are changed. It's like having different shows on the same stage.
(4) Identifier (detector). Its function is to convert the concentration changes of various substances separated in the chromatographic column into electrical signals (voltage or current signals) for the recorder to record. Commonly used identifiers include thermal conductivity cell identifiers, hydrogen flame ion identifiers, and electron capture identifiers.
(5) The configuration part of the temperature control system and the evaluator. This part is mostly composed of electronic components, so it is also called the electronic part. The chromatographic column and the identifier sometimes require a constant temperature in the vaporization chamber (the higher the accuracy, the better), and some departments also need to program the temperature, so the instrument has a precise temperature control device. Generally, it is also equipped with a blower motor and a thermostatic controller for strengthening convection, and a temperature indication or display. The configuration part of the identifier includes DC regulated power supply, amplifier (signal), ignition, polarized power supply, etc.
(6) Recorder. It is an important auxiliary equipment, and its function is to automatically record the signal output by the identifier as a basis for qualitative and quantitative analysis. Generally, electronic potentiometers are commonly used. Nowadays, microcomputer-controlled data processors with printing are widely used, which can not only print out the qualitative and quantitative results of the analyzed components, but also determine whether there are faults and the nature of the faults and print them out, making the analysis results more accurate and faster. meet production needs.
Transformer oil performs important role in power transformers, it works as cooling and insulation material. Therefore, Dissolved Gas Analysis of transformer oil is necessary for predicting the condition of transformer oil. By analyzing the percentages of dissolved gasses contained in transformer oil, maintainence staff can obtain the useful data for their work.
PureTech Oil Filtration
Add：1 Xinmao Road, Beibei district, Chongqing, China