A gas flow metering device

Abstract

The utility model relates to a gas flowmeter technology field, concretely relates to a gas flowmeter device, including differential pressure flowmeter, the upstream side of differential pressure flowmeter is connected with the one end of guide pressure pipe no.

Description

Technical Field

[0001] This utility model relates to the field of gas flow meter technology, and specifically to a gas flow metering device. Background Technology

[0002] In industrial production, differential pressure flow meters are widely used in gas flow measurement scenarios due to their mature structure and wide applicability. In existing technologies, traditional differential pressure flow meters typically only have one differential pressure transmitter, and its measurement range must match the maximum flow requirement of the pipeline design to meet the measurement needs under normal production conditions.

[0003] However, in practical applications, due to the need to reserve capacity for future expansion during the initial design phase, process pipelines are often designed with larger diameters. Alternatively, to achieve energy-saving goals, fluid flow rates may be reduced to minimize pressure loss. Furthermore, process adjustments during production can easily lead to operating conditions of "large diameter, low flow rate" or "large diameter, low flow rate." In such cases, the fluid flow rate may exceed the effective measurement range of a single differential pressure transmitter, causing metering failure at low flow rates. This results in the inability to accurately capture flow signals at low velocities, affecting the integrity and accuracy of the metering.

[0004] To address the limitations of single-range transmitters, some technical solutions employ flow transmitters capable of measuring dual differential pressures. However, most existing such devices are integrated designs, combining two differential pressure measurement units with different ranges into one unit. While this integrated structure enables dual differential pressure measurement, it requires disassembly of the entire device for equipment inspection, maintenance, or component replacement. This complex operation makes it difficult to disassemble individual measurement units, resulting in low maintenance efficiency. Furthermore, the disassembly process may interfere with other components, affecting the overall stability and measurement accuracy of the equipment. Utility Model Content

[0005] To address the problem that existing flow transmitters capable of measuring dual differential pressures are typically integrated designs, requiring disassembly of the entire device for equipment repair, maintenance, or component replacement, which is complex and inconvenient for individual measurement units, resulting in low maintenance efficiency and potential interference with other components during disassembly, affecting the overall stability and metering accuracy of the equipment, this utility model provides a gas flow metering device.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A gas flow metering device includes a differential pressure flow meter. The upstream end of the differential pressure flow meter is connected to one end of a pressure-conducting pipe, and the downstream end of the differential pressure flow meter is connected to one end of a pressure-conducting pipe. The other end of the pressure-conducting pipe is connected to the positive pressure chamber of a conventional differential pressure transmitter and the positive pressure chamber of a micro differential pressure transmitter via a three-way pipe. The other end of the pressure-conducting pipe is connected to the negative pressure chamber of both the conventional differential pressure transmitter and the micro differential pressure transmitter via a three-way pipe. The measurement range of the conventional differential pressure transmitter is larger than that of the micro differential pressure transmitter. A differential pressure control valve is provided between the three-way pipe and the micro differential pressure transmitter. The differential pressure control valve is an automatic on / off valve.

[0007] By adopting the above structural scheme, this utility model, through a parallel dual differential pressure transmitter design, utilizes a conventional differential pressure transmitter to cover the normal flow range and a micro differential pressure transmitter to cover the small flow range, thus solving the metering blind spot in the "large diameter, small flow" scenario. Furthermore, the parallel structure facilitates individual disassembly and maintenance, overcoming the shortcomings of integrated devices. Simultaneously, this utility model utilizes a differential pressure control valve to protect the micro differential pressure transmitter. When the differential pressure value exceeds the tolerance range of the micro differential pressure transmitter, the differential pressure control valve closes to block the impact of high pressure, preventing damage to the micro differential pressure transmitter.

[0008] As a preferred implementation of a gas flow metering device, a first shut-off valve is provided on the first pressure guide pipe, and a second shut-off valve is provided on the second pressure guide pipe. Both the first and second shut-off valves are manual shut-off valves.

[0009] By adopting the above structural scheme, a shut-off valve is installed on the first pressure-conducting pipe and a shut-off valve is installed on the second pressure-conducting pipe. When the whole device needs to be repaired or the transmitter needs to be replaced, the shut-off valves one and two can be manually closed to cut off the pressure connection between the differential pressure flow meter and the subsequent pipeline and transmitter, so as to avoid fluid leakage or pressure shock, ensure the safety of the maintenance process, and facilitate the maintenance operation of the entire measurement system.

[0010] As a preferred implementation of a gas flow metering device, a shut-off valve three is provided between the three-way pipe one and the micro differential pressure transmitter, and a shut-off valve four is provided between the three-way pipe two and the micro differential pressure transmitter. Both shut-off valves three and four are manual shut-off valves.

[0011] By adopting the above structural scheme, a shut-off valve three is installed between the three-way pipe one and the micro differential pressure transmitter, and a shut-off valve four is installed between the three-way pipe two and the micro differential pressure transmitter. When it is necessary to repair or disassemble the micro differential pressure transmitter separately, shut-off valves three and four can be closed to cut off the connection between the micro differential pressure transmitter and the three-way pipe one and three-way pipe two. This does not affect the normal operation of the conventional differential pressure transmitter, realizes independent maintenance of the micro differential pressure transmitter, and improves the maintenance convenience of the device.

[0012] As a preferred implementation of a gas flow metering device, the first three-way pipe is connected to the positive pressure chamber of a conventional differential pressure transmitter through a conventional high-pressure guiding pipe, and the second three-way pipe is connected to the negative pressure chamber of a conventional differential pressure transmitter through a conventional low-pressure guiding pipe; the first three-way pipe is connected to the positive pressure chamber of a micro differential pressure transmitter through a micro high-pressure guiding pipe, and the second three-way pipe is connected to the negative pressure chamber of a micro differential pressure transmitter through a micro low-pressure guiding pipe.

[0013] By adopting the above structural scheme, conventional high-pressure and low-pressure guiding pipes are connected to the positive pressure chamber of the conventional differential pressure transmitter via T-connector 1 and T-connector 2 via T-connector 3 via T-connector 4 via T-connector 5 via T-connector 6 via T-connector 7 via T-connector 8 via T-connector 9 via T-connector 1 via T-connector 1 via T-connector 1 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 1 via T-connector 2 via T-connector 3 via T-connector 1 via T-connector 2 via T-connector 3, ...

[0014] As a preferred implementation of a gas flow metering device, both T-pipe 1 and T-pipe 2 are made of seamless carbon steel pipes, and the inner circumferential surfaces of the three ends of T-pipe 1 and T-pipe 2 are provided with internal threads; the outer circumferential surface of the end of pressure guiding pipe 1, conventional high pressure guiding pipe, and micro high pressure guiding pipe connected to T-pipe 1 is provided with external threads, and the outer circumferential surface of the end of pressure guiding pipe 2, conventional low pressure guiding pipe, and micro low pressure guiding pipe connected to T-pipe 2 is provided with external threads.

[0015] Using the above structural scheme, T-pipe 1 and T-pipe 2 are made of seamless carbon steel pipes, and the inner circumferential surfaces of the three ends are provided with internal threads. The outer circumferential surface of the end where pressure-conducting pipe 1, conventional high-pressure pressure-conducting pipe, and micro-high-pressure pressure-conducting pipe connect to T-pipe 1 is provided with external threads. The outer circumferential surface of the end where pressure-conducting pipe 2, conventional low-pressure pressure-conducting pipe, and micro-low-pressure pressure-conducting pipe connect to T-pipe 2 is provided with external threads. The threaded connection method realizes the detachable connection of each component, which is convenient for installation, disassembly, and replacement. The seamless carbon steel pipe material ensures the strength and corrosion resistance of the pipeline, which is suitable for the complex working conditions of industrial gas metering. At the same time, the threaded connection has good sealing performance, reduces pressure signal leakage, and improves measurement accuracy.

[0016] As a preferred implementation of a gas flow metering device, sealing gaskets are provided on the end faces of the three ends of both the first and second tee pipes.

[0017] By adopting the above structural scheme, sealing gaskets are set on the three end faces of the three-way pipe one and the three-way pipe two, which further enhances the sealing performance of the connection between the three-way pipe and each pressure-conducting pipe, effectively preventing gas medium leakage or outside air from entering the pressure-conducting pipeline, avoiding pressure signal distortion caused by leakage, and ensuring the accuracy of conventional differential pressure transmitters and micro differential pressure transmitters. It is especially suitable for gas metering scenarios with high requirements for sealing performance.

[0018] As a preferred implementation method for gas flow metering devices, conventional differential pressure transmitters have a measurement range of 0-1 MPa, while micro differential pressure transmitters have a measurement range of 0-10 kPa, and both have an accuracy class of no less than ±0.5%FS.

[0019] By adopting the above structural scheme, the measurement range of the conventional differential pressure transmitter is limited to 0-1MPa, and the measurement range of the micro differential pressure transmitter is limited to 0-10kPa. Both have an accuracy class of no less than ±0.5%FS, which clarifies the applicable range of the two types of transmitters. This ensures that the differential pressure corresponding to the normal flow rate is accurately measured by the conventional differential pressure transmitter, and the minute differential pressure corresponding to the small flow rate is accurately captured by the micro differential pressure transmitter. This solves the problem that single-range transmitters cannot cover a wide flow range. At the same time, the high accuracy class ensures the reliability of the measurement data in different differential pressure ranges, providing an accurate basis for gas flow measurement.

[0020] As a preferred implementation of a gas flow metering device, the nominal pressure of shut-off valve one and shut-off valve two is not lower than the maximum working pressure of the differential pressure flow meter.

[0021] By adopting the above structural scheme, the nominal pressure of gate valve one and gate valve two is limited to not less than the maximum working pressure of the differential pressure flow meter. This ensures that gate valve one and two can reliably cut off the pressure-conducting pipeline under the maximum working pressure of the differential pressure flow meter, avoid leakage caused by insufficient valve pressure resistance, and prevent high-pressure fluid from directly impacting downstream transmitters, especially micro differential pressure transmitters. This ensures the safe operation of the device from the main pipeline level, while also ensuring sealing during maintenance.

[0022] As a preferred implementation of a gas flow metering device, the sealing gasket is made of rubber or metal that is resistant to gaseous medium corrosion.

[0023] Using the above solutions, rubbers resistant to gaseous media corrosion, such as nitrile rubber and fluororubber, possess excellent elasticity and can fill minute gaps to form a gapless seal. Furthermore, the rubber material itself does not chemically react with common industrial gases, preventing damage to the sealing surface due to corrosion, such as natural gas and chemical process gases. Metals resistant to gaseous media corrosion possess higher structural stability, such as copper and stainless steel. Under high pressure differential conditions, they can withstand the high-pressure impact of gases without deformation, avoiding leakage caused by gasket deformation. Simultaneously, the metal material's strong corrosion resistance ensures that long-term contact with gaseous media will not cause rust or peeling, maintaining its sealing performance.

[0024] As a preferred implementation of a gas flow metering device, the inner diameter of the conventional high-pressure guiding tube is not less than the inner diameter of the micro-high-pressure guiding tube, and the inner diameter of the conventional low-pressure guiding tube is not less than the inner diameter of the micro-low-pressure guiding tube.

[0025] Using the above structural design, conventional differential pressure transmitters, which need to transmit large differential pressure signals, have higher requirements for transmission efficiency and stability. A larger inner diameter reduces the flow resistance of gas in the pipeline, minimizing attenuation or delay of the pressure signal during transmission, ensuring that the large differential pressure signal can be transmitted completely and quickly to the conventional differential pressure transmitter, and avoiding measurement errors caused by pipeline throttling. Micro differential pressure transmitters, on the other hand, need to capture small differential pressure signals and are less sensitive to pipeline resistance. They can achieve effective signal transmission without requiring a large flow of gas. A smaller inner diameter can meet the transmission requirements of small differential pressure signals without diluting the signal due to excessively thick pipelines, ensuring the accuracy of micro differential pressure measurements.

[0026] The beneficial effects of this utility model include: This invention connects the upstream and downstream sides of a differential pressure flow meter via pressure guide pipes one and two, respectively, and then via three-way pipes one and two, to form a parallel connection with a conventional differential pressure transmitter and a micro differential pressure transmitter. The conventional differential pressure transmitter has a larger measurement range than the micro differential pressure transmitter. Combined with the differential pressure control valve between the three-way pipe and the micro differential pressure transmitter, accurate measurement of different differential pressure ranges is achieved. The conventional differential pressure transmitter covers the differential pressure range corresponding to normal flow rates, while the micro differential pressure transmitter covers the small differential pressure range corresponding to small flow rates, solving the measurement problem in "large pipe diameter, small flow" scenarios. Simultaneously, the parallel design avoids the limitations of integrated structures, facilitating individual disassembly and maintenance of any one differential pressure transmitter. The differential pressure control valve can prevent impact on the micro differential pressure transmitter when the differential pressure value is large, providing protection and ensuring the service life and measurement accuracy of the micro differential pressure transmitter. Attached Figure Description

[0027] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the pipeline connection principle of a gas flow metering device in a specific embodiment of this utility model.

[0029] List of components and reference numerals: 1. Differential pressure flow meter; 2. Pressure guide tube one; 3. Pressure guide tube two; 4. T-junction one; 5. Conventional differential pressure transmitter; 6. Micro differential pressure transmitter; 7. T-junction two; 8. Conventional high-pressure guide tube; 9. Conventional low-pressure guide tube; 10. Micro high-pressure guide tube; 11. Micro low-pressure guide tube; 12. Shut-off valve one; 13. Shut-off valve two; 14. Shut-off valve three; 15. Shut-off valve four; 16. Differential pressure control valve. Detailed Implementation

[0030] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Reference Figure 1 This embodiment proposes a gas flow metering device, including a differential pressure flow meter 1. The upstream side of the differential pressure flow meter 1 is connected to one end of the pressure guiding pipe 2, and the downstream side of the differential pressure flow meter 1 is connected to one end of the pressure guiding pipe 3. The other end of the pressure guiding pipe 2 is connected to the positive pressure chamber of the conventional differential pressure transmitter 5 and the positive pressure chamber of the micro differential pressure transmitter 6 through a three-way pipe 4. The other end of the pressure guiding pipe 3 is connected to the negative pressure chamber of the conventional differential pressure transmitter 5 and the negative pressure chamber of the micro differential pressure transmitter 6 through a three-way pipe 7.

[0032] Specifically, T-connector 4 is connected to the positive pressure chamber of the conventional differential pressure transmitter 5 via the conventional high-pressure guide pipe 8, and T-connector 7 is connected to the negative pressure chamber of the conventional differential pressure transmitter 5 via the conventional low-pressure guide pipe 9; T-connector 4 is connected to the positive pressure chamber of the micro differential pressure transmitter 6 via the micro high-pressure guide pipe 10, and T-connector 7 is connected to the negative pressure chamber of the micro differential pressure transmitter 6 via the micro low-pressure guide pipe 11. The inner diameter of the conventional high-pressure guide pipe 8 is not less than the inner diameter of the micro high-pressure guide pipe 10, and the inner diameter of the conventional low-pressure guide pipe 9 is not less than the inner diameter of the micro low-pressure guide pipe 11.

[0033] The measurement range of the conventional differential pressure transmitter 5 is larger than that of the micro differential pressure transmitter 6. In this embodiment, the measurement range of the conventional differential pressure transmitter 5 can be 0-1MPa, and the measurement range of the micro differential pressure transmitter 6 can be 0-10kPa. The accuracy class of both is not lower than ±0.5%FS.

[0034] To facilitate pipe connections, both T-connector 4 and T-connector 7 are made of seamless carbon steel pipe, and their three ends have internal threads on their inner circumferential surfaces. The outer circumferential surface of the end connecting pressure-conducting pipe 2, conventional high-pressure pressure-conducting pipe 8, and micro-high-pressure pressure-conducting pipe 10 to T-connector 4 has external threads, as does the outer circumferential surface of the end connecting pressure-conducting pipe 3, conventional low-pressure pressure-conducting pipe 9, and micro-low-pressure pressure-conducting pipe 11 to T-connector 7. Sealing gaskets are provided at the end faces of both T-connector 4 and T-connector 7.

[0035] To facilitate further disassembly, a shut-off valve 12 is installed on pressure guide pipe 2, and a shut-off valve 13 is installed on pressure guide pipe 3. Shut-off valves 12 and 13 are manual shut-off valves, and their nominal pressure is not lower than the maximum working pressure of the differential pressure flowmeter 1. A shut-off valve 14 is installed between tee pipe 4 and the micro differential pressure transmitter 6, and a shut-off valve 15 is installed between tee pipe 7 and the micro differential pressure transmitter 6. Both shut-off valves 14 and 15 are manual shut-off valves.

[0036] A differential pressure control valve 16 is installed between the three-way pipe 7 and the differential pressure transmitter 6. The differential pressure control valve 16 is an automatic on / off valve. When the differential pressure value between the upstream and downstream of the differential pressure flowmeter 1 is less than or equal to the preset differential pressure threshold, the automatic on / off valve opens, and the differential pressure transmitter 6 is connected to the measurement circuit; when the differential pressure value is greater than the preset differential pressure threshold, the automatic on / off valve closes, and the differential pressure transmitter 6 is disconnected from the measurement circuit.

[0037] The working process of this embodiment is as follows: When gas flows through the differential pressure flowmeter 1, a pressure difference is generated before and after the throttling element inside: the pressure on the upstream side is higher, and the pressure on the downstream side is lower. This pressure difference signal is transmitted to the three-way pipe 4 and the three-way pipe 7 through the pressure guide pipe 2 and the pressure guide pipe 3, respectively.

[0038] The three-way pipe 4 transmits the upstream high-voltage signal in two paths: it is sent to the positive pressure chamber of the conventional differential pressure transmitter 5 through the conventional high-voltage pressure guide pipe 8, and at the same time, it is sent to the positive pressure chamber of the micro differential pressure transmitter 6 through the micro high-voltage pressure guide pipe 10.

[0039] The three-way pipe 7 splits the downstream low-pressure signal into two paths: it is sent to the negative pressure chamber of the conventional differential pressure transmitter 5 through the conventional low-pressure guide pipe 9, and at the same time, it is sent to the negative pressure chamber of the micro differential pressure transmitter 6 through the micro low-pressure guide pipe 11 (via the differential pressure control valve 16).

[0040] Under low flow rate or low differential pressure conditions, when the differential pressure difference between the upstream and downstream of the differential pressure flowmeter 1 is ≤ the preset low differential pressure threshold (e.g., ≤ 10 kPa), the differential pressure control valve 16 automatically opens, and the low differential pressure transmitter 6 is connected to the measurement circuit to accurately capture the small differential pressure signal and calculate the low flow rate; at this time, the conventional differential pressure transmitter 5 does not participate in effective measurement because its range is too large.

[0041] In normal flow conditions, when the differential pressure value is greater than the preset differential pressure threshold, the differential pressure control valve 16 automatically closes, cutting off the low-pressure signal path of the differential pressure transmitter 6 to prevent damage to the differential pressure transmitter 6 from high pressure impact; at this time, the normal differential pressure transmitter 5 receives the complete differential pressure signal and measures the normal flow.

[0042] If overall maintenance is required, close the stop valves 12 and 13 on pressure guide pipe 12 and pressure guide pipe 23 to cut off the main pressure signal and ensure safe operation.

[0043] If the micro differential pressure transmitter 6 needs to be maintained separately, its dedicated shut-off valves, namely shut-off valve three 14 and shut-off valve four 15, can be closed without affecting the normal operation of the conventional differential pressure transmitter 5, thus enabling independent disassembly and assembly.

[0044] This embodiment solves the metering blind spot of "large diameter, small flow" that cannot be covered by a single-range transmitter by using two transmitters in parallel, differential pressure control valve 16 for protection, and manual shut-off valve for maintenance. It also ensures equipment safety and maintenance convenience, and ultimately achieves accurate metering across the entire flow range.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas flow metering device, comprising a differential pressure flow meter (1), characterized in that, The upstream side of the differential pressure flow meter (1) is connected to one end of the pressure guide pipe (2), and the downstream side of the differential pressure flow meter (1) is connected to one end of the pressure guide pipe (3). The other end of the pressure guide pipe (2) is connected to the positive pressure chamber of the conventional differential pressure transmitter (5) and the positive pressure chamber of the micro differential pressure transmitter (6) through the three-way pipe (4). The other end of the pressure guide pipe (3) is connected to the negative pressure chamber of the conventional differential pressure transmitter (5) and the negative pressure chamber of the micro differential pressure transmitter (6) through the three-way pipe (7). The measurement range of the conventional differential pressure transmitter (5) is larger than that of the micro differential pressure transmitter (6); a differential pressure control valve (16) is provided between the three-way pipe (7) and the micro differential pressure transmitter (6), and the differential pressure control valve (16) is an automatic on / off valve.

2. The gas flow metering device according to claim 1, characterized in that, The pressure guide pipe 1 (2) is equipped with a stop valve 1 (12), and the pressure guide pipe 2 (3) is equipped with a stop valve 2 (13). The stop valve 1 (12) and the stop valve 2 (13) are manual stop valves.

3. The gas flow metering device according to claim 1, characterized in that, A shut-off valve three (14) is provided between the three-way pipe one (4) and the micro differential pressure transmitter (6), and a shut-off valve four (15) is provided between the three-way pipe two (7) and the micro differential pressure transmitter (6). The shut-off valve three (14) and the shut-off valve four (15) are manual shut-off valves.

4. A gas flow metering device according to claim 1, characterized in that, Three-way pipe one (4) is connected to the positive pressure chamber of conventional differential pressure transmitter (5) through conventional high pressure guide pipe (8), and three-way pipe two (7) is connected to the negative pressure chamber of conventional differential pressure transmitter (5) through conventional low pressure guide pipe (9). Three-way pipe one (4) is connected to the positive pressure chamber of micro differential pressure transmitter (6) through micro high pressure guide pipe (10), and three-way pipe two (7) is connected to the negative pressure chamber of micro differential pressure transmitter (6) through micro low pressure guide pipe (11).

5. A gas flow metering device according to claim 4, characterized in that, Both the first tee pipe (4) and the second tee pipe (7) are made of seamless carbon steel pipes, and the inner circumferential surfaces of the three ends of the first tee pipe (4) and the second tee pipe (7) are provided with internal threads; The outer circumferential surface of the end of the pressure guide tube 1 (2), the conventional high pressure guide tube (8), the micro high pressure guide tube (10) connected to the tee tube 1 (4) is provided with external threads. The outer circumferential surface of the end of the pressure guide tube 2 (3), the conventional low pressure guide tube (9), the micro low pressure guide tube (11) connected to the tee tube 2 (7) is provided with external threads.

6. A gas flow metering device according to claim 5, characterized in that, The end faces of the three ends of the first (4) and the second (7) tee pipes are all provided with sealing gaskets.

7. A gas flow metering device according to claim 1, characterized in that, The measurement range of the conventional differential pressure transmitter (5) is 0-1MPa, and the measurement range of the micro differential pressure transmitter (6) is 0-10kPa. The accuracy class of both is not lower than ±0.5%FS.

8. A gas flow metering device according to claim 2, characterized in that, The nominal pressure of stop valve one (12) and stop valve two (13) shall not be lower than the maximum working pressure of differential pressure flow meter (1).

9. A gas flow metering device according to claim 6, characterized in that, The sealing gasket is made of rubber or metal that is resistant to corrosion from gaseous media.

10. A gas flow metering device according to claim 4, characterized in that, The inner diameter of the conventional high-pressure guide tube (8) is not less than the inner diameter of the micro high-pressure guide tube (10), and the inner diameter of the conventional low-pressure guide tube (9) is not less than the inner diameter of the micro low-pressure guide tube (11).

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