Pressure reducing valve for micro-trace gas analysis

Abstract

The invention relates to the field of micro-trace gas analysis, and particularly discloses a pressure reducing valve for micro-trace gas analysis, which is characterized in that the right end of a gas inlet pipe is connected to a pressure sensing diaphragm at a high-pressure acquisition end; a pressure sensing diaphragm of the high-pressure collecting end is connected to the left rear end of the high-pressure adjusting cavity; the pressure sensing diaphragm of the low-pressure collecting end is connected to the right rear end of the low-pressure stabilizing cavity; the left end of the air outlet pipe is connected to a pressure sensing diaphragm of a low-pressure acquisition end; gas enters from a first gas inlet of the gas inlet pipe, sequentially passes through the pressure sensing diaphragm of the high-pressure collecting end, the high-pressure adjusting cavity, the low-pressure stabilizing cavity and the pressure sensing diaphragm of the low-pressure collecting end, and then is exhausted from a second gas outlet of the gas outlet pipe. The high-pressure collecting end, the high-pressure adjusting cavity, the low-pressure stabilizing cavity and the low-pressure collecting end are established, the whole structure of the second gas outlet is finally achieved, only one gas flow path is included, no other bypass structures exist, gas flowing continuity is ensured, and the gas path purging speed is greatly increased.

Description

Technical Field

[0001] The invention relates to the field of micro-trace gas analysis, and in particular to a pressure reducing valve used for micro-trace gas analysis. Background Art

[0002] Trace gases refer to gas components with extremely low content in air or other gases. Usually, the concentration of trace gases is 10 -6 ppm, parts per million to 10 -12 ppm, one part per trillion or even lower. Detection and analysis of trace gases are of great significance in environmental monitoring, industrial production, medical diagnosis and other fields. Commonly used detection methods include gas chromatography, mass spectrometry, infrared spectroscopy, etc.

[0003] In the field of trace gas analysis, the pressure reducing valve is an indispensable key component in the process of gas pressure conversion and transmission. Trace gas analysis requires extremely high precision and reliability, so factors such as adsorption and residue in the gas path may have a significant impact on the final analysis results. The main function of the pressure reducing valve is to reduce the pressure of high-pressure gas to adapt it to the working requirements of subsequent analytical equipment and ensure the stability and accuracy of gas pressure conversion transmission.

[0004] The traditional pressure reducing valve is designed as a fully mechanical structure, and its pressure display relies on the pointer mode. When the pressure of the measured medium changes, the sensitive elements in the pressure gauge, such as the Bourdon tube, diaphragm box, and bellows, will produce elastic deformation. This deformation is transmitted to the pointer through the conversion mechanism inside the movement, causing the pointer to rotate to display the current pressure value. This design requires gas to enter the slender interior of the sensitive element, which inevitably introduces a large dead volume. Since the pressure test structure of the traditional pressure reducing valve is usually located on the bypass structure of the main gas path, it is difficult for the gas flow in the gas path to completely replace the residual gas in this part of the dead volume. When performing micro-trace analysis of gas sampling, this dead volume will introduce residual air or other previously residual gases, thereby bringing impurities, contaminants or interferences to the analysis process, seriously affecting the accuracy of the analysis results.

[0005] In addition, the pointer display method used in traditional pressure reducing valves has obvious limitations. Since the pointer display relies on mechanical elastic deformation, it is easily affected by external vibration, resulting in large pressure display errors. Moreover, the readings of the pointer display are often not intuitive enough and require operators to interpret and judge, which increases the complexity of operation and display errors. Summary of the invention

[0006] The purpose of the present invention is to provide a pressure reducing valve for trace gas analysis, so as to solve the problem that the dead volume is too large during the trace gas analysis, thus affecting the accuracy of the analysis result.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: A pressure reducing valve for trace gas analysis, comprising an air inlet pipe, a low-pressure collection end, a high-pressure collection end, a pressure regulating chamber, an air outlet pipe, and a rotating handle; The pressure regulating chamber includes a high-pressure regulating chamber and a low-pressure stabilizing chamber; a filter screen is provided at the bottom of the high-pressure regulating chamber, a conical valve core is provided in the middle, and a separate pressure regulating hole structure is provided at the top; the low-pressure stabilizing chamber is arranged above the separate pressure regulating hole structure, and the upper part of the conical valve core is inserted into the low-pressure stabilizing chamber; An air inlet pipe, with a first air inlet at the left end and a first air outlet at the right end, the first air outlet being connected to a pressure sensing diaphragm at a high-pressure collection end through a high-pressure through hole; A rotating handle is arranged on the upper part of the pressure regulating chamber, and an adjusting diaphragm is arranged between the rotating handle and the pressure regulating chamber; The pressure sensing diaphragm at the high-pressure collection end is connected to the left rear end of the high-pressure regulating chamber through the high-pressure through hole; The pressure sensing diaphragm at the low-pressure collection end is connected to the right rear end of the low-pressure stabilizing chamber through the low-pressure through hole; An air outlet pipe, the left end of which is connected to a pressure sensing diaphragm at a low-pressure collection end through a low-pressure through hole, and the right end of which is provided with a second air outlet; The gas enters through the first air inlet of the air inlet pipe, passes through the pressure sensing diaphragm at the high-pressure collection end, the high-pressure pressure regulating chamber, the low-pressure stabilizing chamber and the pressure sensing diaphragm at the low-pressure collection end in turn, and is discharged through the second air outlet of the air outlet pipe. The entire air path is designed according to a single-flow path structure, with only one serial air path channel and no bypass structure.

[0008] As a further technical solution of the above scheme, the high-pressure collection end includes a tube body, a pressure sensing diaphragm, a sealing surface, a sensor O-ring, a pressure sensor and a digital display dial; the lower end of the tube body is connected to the left end of the high-pressure pressure regulating chamber, and the tube body is sequentially provided with a sealing surface and a pressure sensing diaphragm, the sensor O-ring is arranged above the sealing surface, the pressure sensor is arranged above the sensor O-ring, and the digital display dial is arranged on the outside of the tube body; the gas passes through the pressure sensing diaphragm to sense the pressure and displays it on the digital display dial.

[0009] As a further technical solution of the above solution, the high-voltage acquisition end also includes a pressure sensor, a temperature sensor and a pressure calibration / temperature compensation module.

[0010] As a further technical solution of the above solution, the low-pressure collecting end has the same structure as the high-pressure collecting end and is connected to the right end of the low-pressure stabilizing chamber through a low-pressure through hole.

[0011] As a further technical solution of the above solution, it also includes a first compression spring, and the first compression spring is arranged on the conical valve core.

[0012] As a further technical solution of the above solution, a spring fixing pad is provided at the bottom of the inner wall of the rotating handle, and a second spring is provided on the spring fixing pad.

[0013] As a further technical solution of the above solution, a first metal seal is provided on the outside of the high-pressure regulating chamber; and a second metal seal is provided on the top of the low-pressure stabilizing chamber.

[0014] As a further technical solution of the above solution, a PEEK sealing gasket is provided outside the separated pressure regulating hole structure.

[0015] As a further technical solution of the above solution, a dome O-ring is provided at the bottom of the rotating handle.

[0016] As a further technical solution of the above solution, an external hexagonal rotating nut is also provided on the left side of the intake pipe.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: the present invention establishes a high-pressure collection end, a high-pressure pressure regulating chamber, a low-pressure stabilizing chamber and a low-pressure collection end, and finally reaches the entire structure of the second gas outlet, which only includes one gas flow path and no other bypass structure, thereby ensuring the continuity of gas flow and greatly accelerating the gas path purge speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the top view of the structure of the device.

[0020] Figure 3 It is a schematic diagram of the cross-sectional structure of the air inlet pipe and the air outlet pipe.

[0021] Figure 4 The flowchart of data collection is shown in Figure 2.

[0022] Figure 5 This is the injection spectrum of this device.

[0023] Figure 6 This is the injection spectrum of a conventional pressure reducing valve on the market.

[0024] Figure 7 This is the purge spectrum of this device.

[0025] Figure 8 This is the purge spectrum of a conventional pressure reducing valve on the market.

[0026] The meanings of the numbers in the figure are as follows: air inlet pipe-1; first air inlet port-11; first air outlet port-12; low-pressure collecting end-2; high-pressure collecting end-3; high-pressure through hole-4; low-pressure through hole-21 tube body-31; pressure sensing diaphragm-32; sealing surface-33; sensor O-ring-34; pressure sensor-35; digital display dial-36; temperature sensor-38; pressure calibration / temperature compensation module-39; high-pressure pressure regulating chamber-41; low-pressure pressure stabilizing chamber-42; filter screen-43; conical valve core-44; separate pressure regulating hole structure-45; first compression spring-46; first metal seal-47; second metal seal-48; PEEK sealing pad-49; air outlet pipe-5; second air outlet port-51; rotating handle-6; adjusting diaphragm-61; spring fixing pad-62; second spring-63; dome O-ring-64; external hexagonal rotating nut-7. DETAILED DESCRIPTION

[0027] The technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention, so as to have a further understanding of the concept of the present invention, the technical problems solved, the technical features constituting the technical scheme and the technical effects brought about.

[0028] like Figure 1-Figure 4 As shown, a pressure reducing valve for trace gas analysis includes an air inlet pipe 1, a low-pressure collection end 2, a high-pressure collection end 3, a pressure regulating chamber, an air outlet pipe 5 and a rotating handle 6; The pressure regulating chamber includes a high-pressure regulating chamber 41 and a low-pressure stabilizing chamber 42; a filter screen 43 is provided at the bottom of the high-pressure regulating chamber 41, a conical valve core 44 is provided in the middle, and a separate pressure regulating hole structure 45 is provided at the top; the low-pressure stabilizing chamber 42 is arranged above the separate pressure regulating hole structure 45, and the upper part of the conical valve core 44 is inserted into the low-pressure stabilizing chamber 42; The air inlet pipe 1 has a first air inlet 11 at the left end and a first air outlet 12 at the right end. The first air outlet 12 is connected to the pressure sensing diaphragm 32 of the high-pressure collection end 3 through the high-pressure through hole 4; A rotating handle 6 is arranged on the upper part of the pressure regulating chamber, and an adjusting diaphragm 61 is also arranged between the rotating handle 6 and the pressure regulating chamber; The pressure sensing diaphragm 32 of the high-pressure collection end 3 is connected to the left rear end of the high-pressure regulating chamber 41 through the high-pressure through hole 4; The pressure sensing diaphragm of the low-pressure collection end 2 is connected to the right rear end of the low-pressure stabilizing chamber 42 through the low-pressure through hole 21; The air outlet pipe 5 has a left end connected to the pressure sensing diaphragm of the low-pressure collection end 2 through a low-pressure through hole, and a second air outlet 51 is provided at the right end; The gas is taken in through the first air inlet 11 of the air inlet pipe 1, passes through the pressure sensing diaphragm 32 of the high-pressure collecting end 3 in sequence, and then passes through the high-pressure pressure regulating chamber 41, the low-pressure stabilizing chamber 42 and the pressure sensing diaphragm of the low-pressure collecting end 2 for pressure collection, and then is discharged through the second air outlet 51 of the air outlet pipe 5.

[0029] The high-pressure collection end 3 includes a tube body 31, a sealing surface 33, a sensor O-ring 34, a pressure sensor 35 and a digital display dial 36; the lower end of the tube body 31 is connected to the high-pressure through hole 4, and a pressure sensing diaphragm 32 and a sealing surface 33 are sequentially arranged in the tube body 31, the sensor O-ring 34 is arranged above the sealing surface 33, the pressure sensor 35 is arranged above the sensor O-ring 34, and the digital display dial 36 is arranged on the outside of the tube body 31; the pressure sensed by the gas passing through the pressure sensing diaphragm 32 is displayed on the digital display dial 36.

[0030] The high-voltage collection end 3 further includes a temperature sensor 38 and a pressure calibration / temperature compensation module 39 .

[0031] The low-pressure collecting end 2 has the same structure as the high-pressure collecting end 3 and is connected to the right rear end of the low-pressure stabilizing chamber 42 through the low-pressure through hole 21 .

[0032] The valve body further includes a first compression spring 46 , which is disposed on the conical valve core 44 .

[0033] A spring fixing pad 62 is provided at the bottom of the inner wall of the rotating handle 6 , and a second spring 63 is provided on the spring fixing pad 62 .

[0034] A first metal seal 47 is disposed outside the high-pressure regulating chamber 41 ; a second metal seal 48 is disposed on the top of the low-pressure stabilizing chamber 42 .

[0035] The separated pressure regulating hole structure 45 is provided with a PEEK sealing gasket 49 outside.

[0036] A dome O-ring 64 is provided at the bottom of the rotating handle 6 .

[0037] An external hexagonal rotating nut 7 is also provided on the left side of the air intake pipe 1 .

[0038] When using this device, gas flows in from the first air inlet 11, passes through the pressure sensing diaphragm 32 of the high-pressure collection end 3, the high-pressure pressure regulating chamber 41, the low-pressure stabilizing chamber 42 and the pressure sensing diaphragm of the low-pressure collection end 2 in sequence, and finally reaches the second air outlet 51. The gas flow path of the entire structure adopts a single-flow gas path structure. The entire gas path adopts a zero dead volume design and only contains one gas flow path without other bypass structures, which ensures the continuity of gas flow and greatly speeds up the gas path purge speed. The pressure sensing diaphragms in the high-pressure collection end 3 and the low-pressure collection end 2 are directly installed in the single-flow gas path structure to ensure that the sensing diaphragm senses the pressure value nearby and achieves a zero dead volume design effect. In addition, the outer edge of the pressure sensing structure is designed as a slightly convex sealing step, and a pure metal seal is used between the single-flow gas path, such as Figure 2 The sealing surface 33 in the apparatus can be preferably selected as a VCR sealing surface in actual use to improve the sealing effect. This unique design has significant advantages in the field of trace gas analysis and can achieve the effect of zero dead body and positive low adsorption, thereby improving the accuracy and reliability of the analysis.

[0039] like Figure 2 As shown, the pressure sensing diaphragm 32, the sealing surface 33, the sensor O-ring 34, the pressure sensor 35 and the digital display dial 36 together constitute a pressure sensing system. Since the pressure sensing diaphragm 32 is directly installed in a single flow path gas path structure through the sealing surface 33, the pressure sensing system can collect gas pressure values ​​with zero dead volume.

[0040] like Figure 3 As shown, the mouth of the gas cylinder enters the air inlet channel through the long-stem nipple, and is fixed to the gas cylinder through the external hexagonal rotating nut 7. After the gas is collected by the inlet pressure sensing system, it passes through the filter screen 43 and enters the high-pressure regulating chamber 41. The high-pressure regulating chamber 41 is installed with a first compression spring 46 and a conical valve core 44; the upper part of the low-pressure stabilizing chamber 42 is provided with an adjusting diaphragm 61. The high-pressure regulating chamber 41 and the low-pressure stabilizing chamber 42 are connected through the separate pressure regulating hole structure 45. The bottom of the conical valve core 44 is connected to the first compression spring 46, and the bottom of the first compression spring is connected to the bottom of the high-pressure regulating chamber 41. The top of the conical valve core passes through the separate pressure regulating hole structure 45 and contacts the diaphragm on the upper part of the low-pressure stabilizing chamber 42. The separate pressure regulating hole structure 45 is sealed and connected to the valve body through the first metal seal 47, and the adjusting diaphragm on the upper part of the low-pressure stabilizing chamber 42 is sealed and fixed to the valve body through the second metal seal 48.

[0041] The upper part of the adjusting diaphragm 61 is the diaphragm dome, and the dome O-ring 64 is on the extension of the diaphragm dome to stabilize the diaphragm dome. A groove is provided on the upper part of the diaphragm dome, and a spring fixing pad 62 is embedded in the diaphragm dome. The second spring 63 is fixed on the spring fixing pad 62 and contacts with the rotating handle 6.

[0042] When the user adjusts the rotating handle, the gas passes through the high-pressure regulating chamber, the conical valve core, and the separated pressure regulating hole structure and then enters the low-pressure stabilizing chamber, and finally forms a dynamic equilibrium state between the first compression spring, the conical valve core, the regulating diaphragm, and the second spring. When the pressure in the low-pressure stabilizing chamber increases, under the action of the pressure in the low-pressure stabilizing chamber, the gas will push the regulating diaphragm upward, and the entire balance structure will push the conical valve core upward, thereby reducing the airflow channel area between the conical valve core and the separated pressure regulating hole structure, reducing the gas flow, and reducing the pressure in the low-pressure stabilizing chamber. Conversely, when the pressure in the low-pressure stabilizing chamber decreases, the entire balance structure will push the conical valve core downward, thereby increasing the airflow channel area between the conical valve core and the separated pressure regulating hole structure, increasing the gas flow, and increasing the pressure in the low-pressure stabilizing chamber. According to the above adjustment process, the valve automatically adjusts the flow area between the high-pressure regulating chamber and the low-pressure regulating chamber, and finally makes the balance structure reach a new dynamic balance, realizing the pressure reduction and stabilization effect on the gas pressure.

[0043] The low-pressure stabilizing cavity is connected to the low-pressure pressure sensing structure through the low-pressure through hole. The pressure data sensed by the low-pressure sensing structure is collected by the pressure sensor and then digitally converted and displayed. The low-pressure sensing structure is connected to the air outlet, and the air at the air outlet can be subjected to micro-trace analysis.

[0044] Figure 4 This is a flow chart of the acquisition process. The signals of the pressure sensor and temperature sensor are converted from analog to digital signals through data acquisition (AD acquisition), and the pressure calibration / temperature compensation module converts the pressure digital signal into an accurate pressure value. The digital structure is equipped with a temperature compensation function. By collecting the temperature value near the pressure sensing structure and performing temperature and pressure fitting, the change in the pressure sensor diaphragm caused by temperature changes is compensated to eliminate the influence of temperature on the pressure value.

[0045] The digital structure of the zero dead volume digital display pressure reducing valve for trace gas analysis also includes a host computer calibration interface, which communicates with the valve pressure calibration / temperature compensation module via USB communication. The digital structure part is provided with a rechargeable lithium battery for power supply, and can also be powered by other batteries. The digital structure part has a low power consumption control function, which can achieve low power consumption control by selecting low power consumption devices, controlling the clock frequency, and flexibly controlling the sleep and wake-up functions. The digital structure part has a digital display function, which can intuitively display the gas pressure value in multiple units, and can display the remaining power, etc.

[0046] In order to ensure the durability and stability of the pressure reducing valve of the present invention, it is necessary to carefully select suitable materials to manufacture the valve body and valve core according to different working environments and usage requirements. These materials should have good mechanical properties, corrosion resistance and thermal stability to cope with various complex working conditions and gas environments.

[0047] In terms of sensor selection, pressure sensors are widely used due to their high sensitivity and reliability. They can monitor the outlet pressure of the pressure reducing valve in real time, and convert this key parameter into an electrical signal and transmit it to the control system. The selection of pressure sensors should not only consider their measurement range, accuracy and volume, but also pay attention to their response speed and stability to ensure that they can accurately and timely reflect the working status of the pressure reducing valve.

[0048] This new type of pressure reducing valve eliminates or reduces dead volume by optimizing the internal structure design and directly collecting gas pressure with the pressure sensor, ensuring that the gas can be evenly mixed during the transmission process. At the same time, the use of advanced pressure sensors and control systems can achieve high-precision regulation, fast response and accurate display of the pressure reducing valve. This new type of pressure reducing valve can not only meet the requirements of accuracy and reliability in the field of trace gas analysis, but also improve analysis efficiency and reduce analysis costs, providing strong support for technological progress and industrial development in the field of trace gas analysis.

[0049] The following will elaborate on the innovative performance of the present invention in terms of innovation, technical effectiveness and micro-trace applications with the help of test examples and comparative examples. Unless otherwise specified, the raw materials and instruments used in all examples are commercially available standard products.

[0050] Gas standard substance 1: Gas standard substance in nitrogen containing 65 volatile organic compounds (VOCs), with a concentration of 100nmol / mol and a pressure of not less than 5MPa, purchased from Sichuan Zhongce Standard Material Technology Co., Ltd.

[0051] Gas standard substance 2: Chlorotoluene gas standard substance in nitrogen, with a concentration of 1 μmol / mol and a pressure of not less than 2 MPa, purchased from Sichuan Zhongce Standard Material Technology Co., Ltd.

[0052] High-purity nitrogen: purity ≥99.999%, purchased from Sichuan Zhongce Standard Technology Co., Ltd.

[0053] Silanized gas pipeline: Made of silanized stainless steel with a diameter of 1 / 16 inch, purchased from Sichuan Shengruiheng Scientific Instrument Co., Ltd.

[0054] In the following examples, the operating parameters of the gas chromatography-mass spectrometry instrument are set as follows: Chromatographic column: DB-1, 60m×250μm×1μm; Injection volume: set to 1 ml, split ratio adjusted to 5:1; Inlet temperature: maintained at 200°C; Column oven program: 5°C, hold for 7 minutes, then increase the temperature to 170°C at a rate of 5°C per minute, then increase the temperature to 220°C at a rate of 15°C per minute, and hold for 7 minutes; Column flow rate: set at 1 ml per minute.

[0055] Test Example 1: This test aims to indirectly reflect the dead volume and adsorption degree of the pressure reducing valve by evaluating the speed of the stabilization time. The faster the stabilization time means the smaller the dead volume and the lower the adsorption degree. The test steps are as follows: S1: Connect the digital pressure reducing valve of the present invention to a gas cylinder containing 65 component gas standard substances in nitrogen; S2: Connect the output end of the digital pressure reducing valve to the inlet of the gas chromatography-mass spectrometer through a silanized pipeline; S3: Adjust the control knob of the digital pressure reducing valve to ensure that the gas flow rate entering the gas chromatography-mass spectrometry instrument is 20 mL / min; S4: Start the gas chromatography-mass spectrometer and start the sample injection process; S5: Continue to observe the fluctuation of the peak area of ​​the response peak until the stable state condition is met: that is, starting from a certain set of data, the relative standard deviation (RSD) of five consecutive sets of data remains below 2%, at which time the response peak is considered to have reached a stable state. At the same time, record the time span from the initial injection moment to the response peak reaching this stable state.

[0056] Comparative Example 1: This comparative example aims to evaluate the dead volume and adsorption degree of different pressure reducing valves by comparing the speed of stabilization time. The faster the stabilization time, the smaller the dead volume of the pressure reducing valve and the lower the adsorption degree. The test steps are as follows: Comparative Example 1 follows the operation method and steps of Test Example 1 to perform the injection test, but the key difference is that the trace digital pressure reducing valve of the present invention used in Test Example 1 is replaced with a pressure reducing valve of other specifications on the market. Other experimental conditions and operation procedures are consistent with Test Example 1.

[0057] The data records of Test Example 1 and Comparative Example 1 are shown in Table 1.

[0058] The injection spectra of Test Example 1 and Comparative Example 1 are as follows: Figure 5 and Figure 6 shown.

[0059] Table 1 is a comparison table of RSD and stabilization time after stabilization of Comparative Example 1 and Test Example 1: .

[0060] Comparison of the results of Test Example 1 and Comparative Example 1 shows that under the same injection conditions, the micro-trace digital pressure reducing valve designed by the present invention exhibits a significantly shorter stabilization time during the micro-trace sample injection process compared to the common pressure reducing valves on the market, and this advantage is more significant when processing high boiling points or heavy components. This fully proves that the micro-trace digital pressure reducing valve of the present invention has a smaller dead volume and lower adsorption characteristics, thus showing a significant performance advantage.

[0061] Test Example 2: This test example aims to indirectly evaluate the dead volume and adsorption level of the pressure reducing valve by measuring the time required to purge the concentration residue to below the detection limit. The shorter the purge time, the smaller the dead volume of the pressure reducing valve and the lower the adsorption level. The test steps are as follows: S1: Connecting the trace digital pressure reducing valve of the present invention to a gas cylinder containing a standard substance of chlorotoluene in nitrogen gas; S2: Close the outlet of the digital pressure reducing valve, adjust the rotary handle until the low pressure dial shows 0.6MPa, and ensure that the inside of the pressure reducing valve is filled with chlorotoluene gas standard substance and maintain this state for no less than 10 minutes; S3: directly connect the digital pressure reducing valve to the high-purity nitrogen cylinder, and connect its output end to the injection port of the gas chromatography-mass spectrometer through a silanized pipeline; S4: By adjusting the rotary handle, the gas flow rate entering the gas chromatography-mass spectrometry instrument is adjusted to 20 mL / min; S5: Start the gas chromatography-mass spectrometer and start the sampling process; S6: Observe the process of the response peak being purged by nitrogen to below the detection limit, and record the purging time required to adjust the flow rate from S4 until the response peak drops below the detection limit.

[0062] Comparative Example 2: Comparative Example 2 follows the test method and steps of Test Example 2, except that the trace digital pressure reducing valve of the present invention used in Test Example 2 is replaced with a pressure reducing valve of other specifications on the market. Other experimental conditions and operation procedures are consistent with Test Example 2.

[0063] The data records of Test Example 2 and Comparative Example 2 are shown in Table 2.

[0064] The injection spectra of Test Example 2 and Comparative Example 2 are as follows: Figure 7 and Figure 8 shown.

[0065] Table 2 is a comparison table of the purge time and residual conditions of Test Example 2 and Comparative Example 2: .

[0066] Comparison of the results of Test Example 2 and Comparative Example 2 shows that, under the same injection conditions, the micro-trace digital pressure reducing valve designed by the present invention has a significantly shorter purge time than the conventional pressure reducing valve on the market in terms of the time required to purge the concentration residue of the sample to below the detection limit. This result shows that the micro-trace digital pressure reducing valve of the present invention has a smaller dead volume and lower adsorption characteristics, and thus has significant advantages.

[0067] The terms “connection” and “fixation” mentioned in the description of the present invention may refer to fixed connection, processing and forming, welding or mechanical connection. The specific meanings of the above terms in the present invention shall be understood according to the specific circumstances.

[0068] In the description of the present invention, the terms "center", "upper", "lower", "horizontal", "inside", "outside", etc., which indicate the orientation or position relationship, are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying a specific orientation that the device or element referred to must have, and therefore cannot be understood as a limitation on the present invention.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure reducing valve for trace gas analysis, characterized in that: It comprises an air inlet pipe (1), a low-pressure collecting end (2), a high-pressure collecting end (3), a pressure regulating chamber, an air outlet pipe (5) and a rotating handle (6); The pressure regulating chamber comprises a high-pressure regulating chamber (41) and a low-pressure stabilizing chamber (42); a filter screen (43) is provided at the bottom of the high-pressure regulating chamber (41), a conical valve core (44) is provided in the middle, and a separate pressure regulating hole structure (45) is provided at the top; the low-pressure stabilizing chamber (42) is arranged above the separate pressure regulating hole structure (45), and the upper part of the conical valve core (44) is inserted into the low-pressure stabilizing chamber (42); An air inlet pipe (1) having a first air inlet (11) at the left end and a first air outlet (12) at the right end, wherein the first air outlet (12) is connected to a pressure sensing diaphragm (32) of a high-pressure collection end (3) via a high-pressure through hole (4); A rotating handle (6) is arranged on the upper part of the pressure regulating chamber, and an adjusting diaphragm (61) is also arranged between the rotating handle (6) and the pressure regulating chamber; The pressure sensing diaphragm (32) of the high-pressure collection end (3) is connected to the left rear end of the high-pressure regulating chamber (41) through the high-pressure through hole (4); The pressure sensing diaphragm of the low-pressure collection end (2) is connected to the right rear end of the low-pressure stabilizing chamber (42) through the low-pressure through hole (21); An air outlet pipe (5), the left end of which is connected to the pressure sensing diaphragm of the low-pressure collection end (2) through a low-pressure through hole, and the right end of which is provided with a second air outlet (51); The gas is taken in through the first gas inlet (11) of the gas inlet pipe (1), passes through the pressure sensing diaphragm (32) of the high-pressure collection end (3) in sequence, then passes through the high-pressure pressure regulating chamber (41), the low-pressure stabilizing chamber (42) and the pressure sensing diaphragm of the low-pressure collection end (2) for pressure collection, and then is discharged through the second gas outlet (51) of the gas outlet pipe (5).

2. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: The high-pressure collection end (3) comprises a tube body (31), a sealing surface (33), a sensor O-ring (34), a pressure sensor (35) and a digital display dial (36); the lower end of the tube body (31) is connected to the high-pressure through hole (4); a pressure sensing diaphragm (32) and a sealing surface (33) are arranged in sequence in the tube body (31); the sensor O-ring (34) is arranged above the sealing surface (33); the pressure sensor (35) is arranged above the sensor O-ring (34); and the digital display dial (36) is arranged outside the tube body (31); the pressure sensed by the gas passing through the pressure sensing diaphragm (32) is displayed on the digital display dial (36).

3. A pressure reducing valve for trace gas analysis as claimed in claim 2, characterized in that: The high-voltage collection end (3) also includes a temperature sensor (38) and a pressure calibration / temperature compensation module (39).

4. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: The low-pressure collecting end (2) has the same structure as the high-pressure collecting end (3), and is connected to the right rear end of the low-pressure stabilizing chamber (42) via a low-pressure through hole (21).

5. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: It also includes a first compression spring (46), which is arranged on the conical valve core (44).

6. A pressure reducing valve for trace gas analysis as claimed in claim 1, characterized in that: A spring fixing pad (62) is provided at the bottom of the inner wall of the rotating handle (6), and a second spring (63) is provided on the spring fixing pad (62).

7. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: A first metal seal (47) is provided on the outside of the high-pressure regulating chamber (41); and a second metal seal (48) is provided on the top of the low-pressure stabilizing chamber (42).

8. A pressure reducing valve for trace gas analysis as claimed in claim 1, characterized in that: The separated pressure regulating hole structure (45) is provided with a PEEK sealing gasket (49) outside.

9. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: A dome O-ring (64) is provided at the bottom of the rotating handle (6).

10. A pressure reducing valve for trace gas analysis according to claim 1, characterized in that: An external hexagonal rotating nut (7) is also provided on the left side of the air intake pipe (1).

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