Preparation device of standard adsorption tube

Abstract

The utility model discloses a preparation device of a standard adsorption tube, which relates to the technical field of volatile organic compound detection, comprises a first pipeline and a second pipeline, and is characterized in that the front end of the first pipeline is connected with a standard gas inlet, and the front end of the second pipeline is connected with a diluent gas inlet; the rear end of the first pipeline and the rear end of the second pipeline are simultaneously connected with the front end of the third pipeline; a sonic nozzle is mounted on the first pipeline, a first branch pipe is connected to the first pipeline, and the front end of the first branch pipe is connected to the position between the standard gas inlet and the sonic nozzle; a sonic nozzle is mounted on the second pipeline, and a needle valve and a pressure gauge are further mounted at the front end of the second pipeline; the gas standard substance is selected for preparation, the defect that a standard adsorption tube is prepared by using a liquid standard substance is avoided, and the device has the advantages of convenience in operation, high adsorption efficiency, adjustable flow, selectable gas types and the like, and can be used for quickly preparing the standard adsorption tube.

Description

Technical Field

[0001] The utility model relates to the technical field of volatile organic compound detection, in particular to a preparation device for a standard adsorption tube. Background Art

[0002] Volatile organic compounds may exist in the environment and food in which humans live, including benzene, alcohols, ketones, esters, and alkanes. Volatile organic compounds are ecotoxic, increase the risk of leukemia, and may also cause pharyngitis and cardiovascular diseases.

[0003] Automobile exhaust, building materials, organic solvents, and artificial furniture release volatile organic compounds such as alkanes and benzene.

[0004] Food additive carbon dioxide is widely used in beverage and ice cream industries, and it contains volatile organic compounds such as benzene and oxygen-containing organic compounds. Therefore, the detection of volatile organic compounds in the food and environmental fields is very important.

[0005] The detection method for volatile organic compounds in the gas is thermal desorption-gas chromatography-mass spectrometry, which is a standard method for detecting volatile organic compounds in ambient air developed by the U.S. Environmental Protection Agency (EPA), the International Organization for Standardization (ISO) and the Ministry of Ecology and Environment of China.

[0006] This method uses an adsorption tube to absorb the substance to be tested in the gas, then uses a thermal desorber to desorb it, and finally uses an instrument to detect it. This method uses a standard adsorption tube prepared in the laboratory for quantitative calibration and draws a working curve.

[0007] The national standard stipulates that standard adsorption tubes are prepared by gas standard substances or liquid standard substances. In China, liquid standard substances are generally used for preparation. The preparation method is to first transfer a certain amount of commercially available certified standard solution, dilute it with methanol, prepare a standard series of target concentrations, and then use a micro-syringe to transfer the standard series and inject it into the adsorption tube to prepare a standard adsorption tube.

[0008] The preparation of standard adsorption tubes using liquid standard substances is a time-consuming, tedious process that is prone to introduce analytical errors. The prepared standard adsorption tubes have poor stability and obvious matrix effects, which can easily cause deviations in the final test results.

[0009] The national standard also stipulates that standard adsorption tubes should be prepared with gas standard substances. However, due to the incomplete description of the method in the standard and the lack of commercial gas standard adsorption tube preparation equipment, this method has not been effectively applied. Laboratory studies have shown that there is a significant deviation in the sample value determination between gas standard substances and liquid standard substances, so it is necessary to establish the preparation technology of gas standard substances and standard adsorption tubes.

[0010] The configuration of adsorption tubes for gas standard substances will also bring a series of problems, mainly:

[0011] 1. The content of the target substance to be analyzed is low, so the content of the required gas standard substance is extremely low, which increases the difficulty of gas matching;

[0012] 2. There are few manufacturers on the market that can provide low-content volatile organic gas standard substances, but the technology for preparing medium-content organic gas standard substances is very mature;

[0013] 3. How to accurately adsorb gas standard substances into adsorption tubes without leakage and diffusion.

[0014] In order to solve the above problems, the utility model provides a preparation device for a standard adsorption tube. Utility Model Content

[0015] The utility model aims to solve the defects in the prior art and proposes a preparation device for a standard adsorption tube.

[0016] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0017] A preparation device for a standard adsorption tube comprises a first pipeline and a second pipeline, wherein the front end of the first pipeline is connected to a standard gas inlet, the front end of the second pipeline is connected to a dilution gas inlet, and the rear ends of the first pipeline and the second pipeline are simultaneously connected to the front end of a third pipeline;

[0018] The first pipeline is installed with a sonic nozzle, and the first pipeline is connected with a first branch pipe, and the front end of the first branch pipe is connected to the position between the standard gas inlet and the sonic nozzle;

[0019] The second pipeline is equipped with a sonic nozzle, and the front end of the second pipeline is also equipped with a needle valve and a pressure gauge;

[0020] A second branch pipe is also installed at the connection between the first pipeline, the second pipeline and the third pipeline;

[0021] The front end of the third pipeline is connected to the first pipeline, the second pipeline and the second branch pipe, and the rear end of the third pipeline is sequentially installed with the third branch pipe, the ball valve, the adsorption tube and the mass flow meter.

[0022] Furthermore, a needle valve and a pressure gauge are installed at the rear end of the first branch pipe.

[0023] Furthermore, a needle valve and a pressure gauge are installed on the second branch pipe.

[0024] Furthermore, a needle valve is installed on the third branch pipe.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The utility model uses gas standard substances for preparation, avoiding the disadvantages of using liquid standard substances to prepare standard adsorption tubes. The device is easy to operate, has high adsorption efficiency, and has the advantages of adjustable flow rate and selectable gas types, and can quickly prepare standard adsorption tubes.

[0027] 2. The utility model can improve the preparation efficiency, stability and accuracy of standard adsorption tubes, filling the domestic technical gap.

[0028] 3. This utility model is suitable for food safety, environmental monitoring, automobile industry and electronics industry, etc., ensuring the reliability, comparability and traceability of the test results, and is of great significance to food safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0030] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0031] In the figure: 1 first pipeline, 2 second pipeline, 3 third pipeline, 4 standard gas inlet, 5 dilution gas inlet, 6 first branch, 7 second branch, 8 third branch, 9 needle valve, 10 pressure gauge, 11 sonic nozzle, 12 ball valve, 13 adsorption tube, 14 mass flow meter. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention;

[0033] Reference Figure 1 , a preparation device for a standard adsorption tube, comprising a first pipeline 1 and a second pipeline 2, characterized in that the front end of the first pipeline 1 is connected to a standard gas inlet 4, the front end of the second pipeline 2 is connected to a dilution gas inlet 5, and the rear ends of the first pipeline 1 and the second pipeline 2 are simultaneously connected to the front end of a third pipeline 3;

[0034] A sonic nozzle 11 is installed on the first pipeline 1, and a first branch pipe 6 is connected to the first pipeline 1, and the front end of the first branch pipe 6 is connected to the position between the standard gas inlet 4 and the sonic nozzle 11; a needle valve 9 and a pressure gauge 10 are installed at the rear end of the first branch pipe 6.

[0035] A sonic nozzle 11 is installed on the second pipeline 2, and a needle valve 9 and a pressure gauge 10 are also installed at the front end of the second pipeline 2;

[0036] A second branch pipe 7 is also installed at the connection between the first pipeline 1 , the second pipeline 2 and the third pipeline 3 ; a needle valve 9 and a pressure gauge 10 are installed on the second branch pipe 7 .

[0037] The front end of the third pipeline 3 is connected to the first pipeline 1, the second pipeline 2 and the second branch pipe 7. The rear end of the third pipeline 3 is sequentially installed with the third branch pipe 8, the ball valve 12, the adsorption tube 13 and the mass flow meter 14. The third branch pipe 8 is installed with a needle valve 9.

[0038] The working principle and general process of the utility model are as follows:

[0039] The standard gas containing active substances is transported to the first pipeline 1 through the standard gas inlet 4. In order to ensure that the active substances pass through the sonic nozzle 11 smoothly, the first branch pipe 6 is connected to the first pipeline 1, and the connection point of the first branch pipe 6 is on the first pipeline 1 between the standard gas inlet 4 and the sonic nozzle 11. At the same time, the first branch pipe 6 is installed with a needle valve 9 and a pressure gauge 10 for adjusting the standard gas pressure in the first pipeline 1;

[0040] The dilution gas is delivered to the second pipeline 2 through the dilution gas inlet 5, and the dilution gas pressure is adjusted by the needle valve 9 and the pressure gauge 10 installed on the second pipeline 2;

[0041] The dilution gas and the standard gas are evenly mixed at the front end of the third pipeline 3, and a second branch pipe 7 is set at the mixing point, and a needle valve 9 and a pressure gauge 10 are set at the second branch pipe 7, which are used to adjust the gas pressure at the mixing point; in addition, a third branch pipe 8 is connected to the rear end, and a needle valve 9 is installed on the third branch pipe 8, which is used to adjust the pressure of the gas flowing into the ball valve 12 and the adsorption tube 13. When the mixed gas flows through the adsorption tube 13, the active substance therein can be adsorbed by the adsorption tube 13, and finally the mass flow meter 14 can calculate the content of the active substance adsorbed by the adsorption tube 13, thereby preparing a standard adsorption tube 13.

[0042] Among them, when the gas passes through the sonic nozzle 11, the gas increases in velocity and decreases in pressure when passing through the gradually contracting section by using the gradually contracting and expanding channel, and forms a critical gas flow at the minimum cross-section, and then converts the velocity kinetic energy into pressure energy through the gradually expanding section, so that the pressure can be restored. When the sonic condition is reached, the function of pressure to flow is linear. If there are two parallel gas paths, one of which can achieve the preparation of different concentrations of standard gas by changing the pressure, and the other can constantly flow out stable and pure gas. After the two gases are fully mixed, the purpose of preparing a series of adsorption tubes is achieved.

[0043] In order to prevent the active substances in the preparation of standard products from being adsorbed by the pipeline or device components, the device places the electronic pressure regulator in the bypass of the pipeline to control the pipeline pressure. The active substances do not need to pass through the pressure regulator, but directly enter the standard hole, generate a constant flow rate under a certain pressure to enter the gas mixing area, ensure that the gas is not contaminated, and improve the stability of the preparation of standard products.

[0044] When the device is working, the outlet of the mixing zone outlet produces standard gas with adjustable concentration within a certain range. At this time, the gas path will be split, and one gas will flow through the standard adsorption tube at a certain flow rate, and then be discharged through the mass flow meter. The sampling volume can be controlled by the mass flow meter. Because the gas path first passes through the adsorption tube and then flows into the mass flow meter, the control element does not come into contact with the gas, and the mass flow meter will not be contaminated by the standard. The excess gas is discharged by the bypass. Through this design, the sampling concentration and sampling volume can be controlled, and the quality of the standard in the adsorption tube can be controlled.

[0045] The connection between the adsorption tube 13 and the third pipeline 3 adopts a silanized ferrule joint, which can effectively ensure the sealing and inertness of the entire system, eliminate any impact of environmental leakage, and ensure the integrity and accuracy of the product sample.

Claims

1. A device for preparing a standard adsorption tube, comprising a first pipeline (1) and a second pipeline (2), characterized in that: The front end of the first pipeline (1) is connected to a standard gas inlet (4), the front end of the second pipeline (2) is connected to a dilution gas inlet (5), and the rear end of the first pipeline (1) and the rear end of the second pipeline (2) are simultaneously connected to the front end of the third pipeline (3); The first pipeline (1) is provided with a sonic nozzle (11), and the first pipeline (1) is connected to a first branch pipe (6), the front end of the first branch pipe (6) being connected to a position between the standard gas inlet (4) and the sonic nozzle (11); The second pipeline (2) is provided with a sonic nozzle (11), and a needle valve (9) and a pressure gauge (10) are also provided at the front end of the second pipeline (2); A second branch pipe (7) is also installed at the connection between the first pipeline (1), the second pipeline (2) and the third pipeline (3); The front end of the third pipeline (3) is connected to the first pipeline (1), the second pipeline (2) and the second branch pipe (7), and the rear end of the third pipeline (3) is sequentially installed with a third branch pipe (8), a ball valve (12), an adsorption tube (13) and a mass flow meter (14).

2. The preparation device of a standard adsorption tube according to claim 1, characterized in that: A needle valve (9) and a pressure gauge (10) are installed at the rear end of the first branch pipe (6).

3. The preparation device of a standard adsorption tube according to claim 1, characterized in that: A needle valve (9) and a pressure gauge (10) are installed on the second branch pipe (7).

4. The preparation device of a standard adsorption tube according to claim 1, characterized in that: A needle valve (9) is installed on the third branch pipe (8).

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