A flammable gas detector batch test tool

Abstract

The utility model belongs to oil gas detection equipment technical field discloses a combustible gas detector batch calibration tool, including and butt joint device of detection device, butt joint device includes gas valve and connecting valve, and the gas valve is opened with each other's intercommunication gas outlet and a plurality of gas inlets, and the connecting valve includes: sampling pipe, and the gas inlet end of sampling pipe can extend into or exit the gas outlet, and the gas outlet end of sampling pipe is communicated with the detection end of detection device through the pipeline, inflation spare, is located in the gas inlet end of sampling pipe, is used for the gap between the gas inlet end of sampling pipe and the gas outlet after inflation seals, air hole is communicated with inflation spare and the inner chamber of sampling pipe respectively, and this scheme is through inflation spare and is tightly attached to the inner wall of gas outlet after pressure expansion, fills the gap between the gas inlet end of sampling pipe and the gas outlet, realizes the quick sealing communication of sampling pipe and detector detection port, the utility model solves the problem that the detector detection port and gas valve butt joint fast.

Description

Technical Field

[0001] This solution belongs to the technical field of oil and gas detection equipment, specifically involving a batch calibration fixture for combustible gas detectors. Background Technology

[0002] Combustible gases such as methane, propane, acetylene, and liquefied petroleum gas, which are widely used in industrial production and civil applications, are usually stored in seamless steel cylinders in the form of high-pressure compression or cryogenic liquefaction for centralized storage, long-distance transportation, and on-site decentralized use. Gas cylinders are currently the most important storage and transportation carriers for combustible gases, and their application scenarios cover multiple industries such as chemical, metallurgical, construction, and gas supply.

[0003] Because flammable gases are highly flammable and explosive, even minor leaks at the cylinder valve assembly, cylinder welds, and connecting pipelines can cause gas to accumulate in confined or poorly ventilated spaces, mixing with air to form an explosive mixture. If this mixture encounters an open flame, static spark, or high-temperature heat source, it can easily ignite a fire, explosion, or other serious accident. Therefore, flammable gases must undergo rigorous mandatory factory testing after bottling.

[0004] See the existing publication (announcement) document CN102518948A, which discloses an apparatus and method for detecting combustible gas leaks. In this apparatus, at one end of a negative pressure container, a vacuum pump is connected to the negative pressure container in sequence through a first electromagnetic vacuum valve and a one-way valve, and a pressure-stabilizing vacuum pump is connected to the negative pressure container in sequence through an automatic control proportional valve and a one-way valve. At the other end of the negative pressure container, a gas detection tube is connected to the negative pressure container in sequence through a combustible gas detector, a flow meter, and a second electromagnetic valve.

[0005] For example, the aforementioned device, by incorporating a first electromagnetic vacuum valve, a second electromagnetic vacuum valve, and an automatic control proportional valve, achieves continuous or intermittent control of the combustible gas detection within the container. To prevent gas leakage within the negative pressure container, the electromagnetic valves are typically connected to the container's valve interface via threads. However, in large-scale production scenarios, the factory inspection of combustible gas cylinders requires batch inspection, with each batch generally consisting of multiple cylinders. Inspection typically employs a multi-cylinder centralized parallel testing mode (e.g., ...). Figure 1 (As shown). When conducting batch testing, if operators need to screw and seal the detection port of the detection device to the gas cylinder valve interface of each device individually, the docking operation will be cumbersome and time-consuming for each device, which cannot meet the needs of rapid factory verification for large batches. Utility Model Content

[0006] The purpose of this solution is to provide a batch calibration fixture for combustible gas detectors to solve the problem of rapid connection between the detector's detection port and the gas valve.

[0007] To achieve the above objectives, this solution provides a batch calibration fixture for combustible gas detectors, including a detection device and a docking device. The docking device includes a gas valve and a connecting valve. The gas valve has an interconnected gas outlet and several gas inlets. The connecting valve includes: The sampling tube has an inlet end that can extend into or out of the outlet end, and the outlet end of the sampling tube is connected to the detection end of the detection device through a pipe. An expansion member is provided at the air inlet end of the sampling tube and is used to seal the gap between the air inlet end and the air outlet of the sampling tube after expansion. A vent is provided at the air inlet end of the sampling tube and penetrates the tube wall of the sampling tube. The vent is connected to the expansion member and the inner cavity of the sampling tube respectively. A one-way valve is provided in the vent hole to allow gas in the sampling tube cavity to flow into the expansion element in one direction. An air pump, which is connected to the sampling tube via a pipeline.

[0008] The principle and effect of this solution are as follows: multiple air inlets configured on the gas valve can be connected to corresponding gas cylinders to be tested, thereby enabling simultaneous batch gas calibration. When connecting the outlet to the sampling tube, the inlet end of the sampling tube is inserted into the outlet of the gas valve. The gas pump delivers gas into the inner cavity of the sampling tube, and the airflow passes through the vent of the built-in one-way valve into the expansion element. After the expansion element expands under pressure, it tightly fits against the inner wall of the outlet, filling the gap between the inlet end and the outlet of the sampling tube, thus achieving rapid sealing and connection between the sampling tube and the detector's detection port. Finally, sampling and measurement are performed. This solution solves the problem of cumbersome operation when connecting the detection port to the gas valve and improves the efficiency of batch calibration.

[0009] Furthermore, the connecting valve also includes a pressure relief hole, which is located at the air inlet end of the sampling tube and penetrates the tube wall of the sampling tube. The pressure relief hole is connected to the inner cavity of the expansion member and the sampling tube respectively. The pressure relief hole is equipped with a pressure relief valve, which is used to allow the gas in the expansion member to flow into the sampling tube in one direction, and the opening pressure of the pressure relief valve is greater than the opening pressure of the one-way valve.

[0010] The principle and effect of this solution are as follows: After gas detection and calibration, high-pressure gas remains inside the expansion component, which is always in an expanded and sealed state. The sampling tube cannot be directly pulled out from the gas valve outlet; the expansion component must be depressurized and retracted before disassembly can be completed. This solution uses a pressure relief hole with a pressure relief valve at the gas inlet end of the sampling tube, and ensures that the opening pressure of the pressure relief valve is greater than the opening pressure of the one-way valve in the vent hole. During the calibration process, the gas pressure output by the air pump can only open the one-way valve, allowing gas to normally fill the expansion component and achieve a sealed connection. At this time, the pressure relief valve is in a closed state, which can maintain the expansion sealing pressure of the expansion component. After the calibration is completed, the pressure relief valve is opened, and the high-pressure gas inside the expansion component flows back to the inner cavity of the sampling tube through the pressure relief hole, causing the expansion component to depressurize and retract, releasing the seal between the sampling tube and the gas valve outlet. At this time, it is easy to manually pull out the sampling tube.

[0011] Furthermore, the air pump's inlet is connected to a nitrogen source; the air pump is an integrated pumping and filling pump.

[0012] The principle and effect of this scheme are as follows: Before the calibration operation, the sampling tube can be purged and replaced with nitrogen to remove residual air and impurities inside the pipeline, so as to avoid interfering with the calibration gas concentration. The nitrogen is pressurized by an air pump (the pressure must be less than the opening pressure of the pressure relief valve). The pressurized nitrogen can open the one-way valve and fill the air bag, causing it to expand and seal the gap. After the calibration is completed, the air pump's suction function creates a negative pressure environment inside the sampling tube, which can open the pressure relief valve in reverse, allowing the gas inside the air bag to flow back and release pressure. The air bag quickly retracts, making it easy to disassemble and separate the sampling tube.

[0013] Furthermore, the inflator is an airbag.

[0014] The principle and effect of this solution are as follows: the airbag can elastically expand and contract with inflation and deflation, and has a good sealing effect with the inner wall of the air valve outlet.

[0015] Furthermore, the expansion member is annular.

[0016] The principle and effect of this solution is to improve the fit between the expansion component and the inner wall of the air outlet.

[0017] Furthermore, both the one-way valve and the pressure relief valve include a sealing ball and a spring, respectively. The sealing ball is used to seal the vent or pressure relief hole, and one end of the spring is fixedly connected to the sealing ball, while the other end is fixedly connected to the inner wall of the vent or pressure relief hole.

[0018] The principle and effect of this solution are as follows: relying on the spring force to press the sealing ball, a normal seal is achieved for the vent and pressure relief holes. During the calibration and inflation process, the positive pressure airflow from the nitrogen source can overcome the spring force of the one-way valve, opening the sealing ball to guide the air passage, allowing nitrogen to fill the air bladder and expand. At this time, the pressure relief valve remains closed and sealed under the pressing action of its own spring. When the calibration is completed and the pressure is released, the air pump draws air to create a negative pressure environment, which can overcome the spring force of the pressure relief valve to pull open the sealing ball, allowing the gas in the air bladder to flow back and release pressure. At the same time, the one-way valve is further pressed and sealed under the negative pressure and the action of the spring.

[0019] Furthermore, the outlet is provided with a blocking ball for sealing the outlet, and the blocking ball is fixedly connected to a tension spring, the free end of which is fixedly connected to the inner wall of the outlet; the inlet end of the sampling tube is used to drive the sealing ball away from the outlet.

[0020] The principle and effect of this solution are as follows: Under normal conditions, the tension spring relies on its own elasticity to pull the blocking ball to fit and seal the gas outlet; when the sampling tube is inserted into the gas outlet to complete the docking operation, the end pushes the blocking ball, causing it to overcome the tension of the tension spring and leave the sealed position, opening the gas flow channel between the gas valve and the sampling tube, so that the test gas can be transported to the sampling tube; after the test is completed and the sampling tube is pulled out, the tension spring rebounds and can drive the blocking ball to reset, resealing the gas outlet.

[0021] Furthermore, the diameters of the two ends of the vent, air outlet, and pressure relief hole gradually decrease along their axial direction.

[0022] The principle and effect of this solution are as follows: by adopting the above-mentioned narrowing structure, the sealing effect with the sealing ball and the blocking ball is better.

[0023] Furthermore, the connecting valve also includes a valve body, which has a through groove for accommodating the sampling tube; the inlet and outlet of the sampling tube are respectively located outside the groove opening.

[0024] The principle and effect of this scheme are as follows: the valve body is the base for connecting the valve, and the through groove is used to support the sampling tube, so that the sampling tube passes through the axis of the through groove.

[0025] Furthermore, a valve seat is fixedly connected to the side of the valve body near the air inlet end of the sampling tube, and the valve seat has a limiting groove that matches the outer wall of the air valve.

[0026] The principle and effect of this solution is to constrain the docking position of the sampling tube and the gas valve outlet by means of the valve body, valve seat and limiting groove, so as to avoid the displacement during the docking process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the batch calibration fixture for the combustible gas detector of this utility model; Figure 2This is a schematic diagram of the internal structure of the docking device of this utility model. Figure 1 ; Figure 3 for Figure 2 A magnified view of a portion of point B in the middle; Figure 4 This is a schematic diagram of the internal structure of the docking device of this utility model. Figure 2 ; Figure 5 for Figure 4 A magnified view of a portion of point C.

[0028] The corresponding labels in the attached diagram are named as follows: Detection device 1, air valve 2, air inlet 21, air outlet 22, connecting valve 3, sampling tube 31, valve body 312, valve seat 313, expansion component 32, vent hole 33, air pump 34, pressure relief hole 35, sealing ball 36, spring 361, blocking ball 37, tension spring 371. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0030] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0031] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features, used to distinguish and describe features, without any order or emphasis. In the description of this utility model, unless otherwise stated, "multiple" means two or more.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] The following is in conjunction with the appendix Figure 1-5 This invention describes a batch calibration fixture for a combustible gas detector, comprising a detection device 1 and a docking device, wherein the docking device consists of a gas valve 2 and a connecting valve 3. The detection device 1 is a readily available and mature combustible gas detection device capable of detecting the concentration of combustible gas in a pipeline and determining whether the gas cylinder under test is leaking. This application primarily addresses... Figure 1 The docking device at position A in the diagram will be specifically improved, and its specific structure is as follows: Please continue reading. Figure 2 The gas valve 2, serving as a transfer component between the gas cylinder to be tested and the testing system, has one interconnected outlet 22 and three inlets 21. The inlets 21 can be connected to a standard gas cylinder connector via pipes, allowing for the connection of three combustible gas cylinders to be tested, thus enabling parallel batch testing of multiple cylinders. The connecting valve 3, serving as a quick-connect component, includes a valve body 312. The valve body 312 has a through groove (not shown) extending along its axial direction. A sampling tube 31 passes through this through groove, with its outer wall sealing against the through groove to prevent gas from escaping through the gaps. Both the inlet and outlet ends of the sampling tube 31 extend beyond the opening of the through groove. A valve seat 313 is fixedly connected to the side of the valve body 312 near the air inlet end of the sampling tube 31. The valve seat 313 has a cylindrical limiting groove (not shown) that matches the outer wall contour of the end of the air valve 2. When docking, the end of the air valve 2 is inserted into the limiting groove, so that the sampling tube 31 and the air outlet 22 can be coaxially positioned, avoiding radial displacement during the insertion process.

[0034] Please continue reading. Figures 2-5An annular expansion member 32 is fitted around the air inlet end of the sampling tube 31. In this embodiment, the expansion member 32 is an annular air bladder made of nitrile rubber that is resistant to oil and gas corrosion. Its inner circumferential surface is bonded and fixed to the outer wall of the sampling tube 31 with sealant to ensure that there is no gas leakage between the expansion member 32 and the sampling tube 31. A vent hole 33 is provided on the wall of the air inlet end of the sampling tube 31, penetrating the tube wall. The vent hole 33 is located at the position where the expansion member 32 is directly opposite the wall of the sampling tube 31, and the inner end of the vent hole 33 is connected to the inner cavity of the sampling tube 31, and the outer end is connected to the inner cavity of the expansion member 32. To prevent gas leakage within the expansion member 32, a one-way valve is installed in the vent 33. This one-way valve consists of a sealing ball 36 and a spring 361. One end of the spring 361 is fixedly connected to the inner wall step of the vent 33, and the other end is fixedly connected to the sealing ball 36. Under normal conditions, the elastic force of the spring 361 presses the sealing ball 36 tightly against the inner constricted end of the vent 33, achieving a one-way seal of the vent 33, allowing gas to flow only from the inner cavity of the sampling tube 31 into the interior of the expansion member 32. The outlet end of the sampling tube 31 is connected to the detection end of the detection device 1 through a high-pressure rubber hose resistant to oil and gas corrosion. The middle of the side wall of the sampling tube 31 is connected to the air port of the integrated pump 34 through a branch pipe. The inlet end of the pump 34 is connected to a high-purity nitrogen source. Nitrogen, as an inert driving medium, can both drive the expansion element 32 to expand and seal, and purge and replace the entire testing pipeline before calibration, removing residual air and impurities to avoid interfering with the concentration detection results of combustible gases. During the docking and sealing operation, the inlet end of the sampling tube 31 is inserted into the outlet 22 of the gas valve 2. The gas pump 34 is started to fill the inner cavity of the sampling tube 31 with nitrogen. When the nitrogen pressure exceeds the preload of the one-way valve spring 361, the airflow pushes open the sealing ball 36 and fills the interior of the expansion element 32 through the vent 33. This causes the expansion element 32 to expand radially under pressure, tightly fitting against the inner wall of the outlet 22, filling the annular gap between the outer wall of the sampling tube 31 and the inner wall of the outlet 22, achieving a threadless, rapid sealing connection and improving the efficiency of rapid calibration of large batches of gas cylinders. It should be noted that the axial thrust generated by the gas pressure inside the gas cylinder acting on the end face of the expansion member 32 is less than the static friction between the outer circumferential surface of the expansion member 32 and the inner wall of the outlet 22. Therefore, when the gas cylinder valve is opened to introduce the gas to be tested, the gas inside the gas cylinder will not push the expansion member 32 to move axially along the outlet 22, so that the expansion member 32 is fitted and fixed to the inner wall of the outlet 22 and will not detach from the pipe wall, causing a seal failure. Secondly, when the gas inside the gas cylinder enters the sampling tube 31, its pressure is also less than the opening pressure of the one-way valve, so the vent 33 will not be in a conductive state. At the same time, during testing, the gas cylinder valve only needs to be opened and then closed to allow the gas to enter the sampling tube 31, and the gas cylinder valve will not be kept in the open position.

[0035] Please continue reading. Figures 2-5To prevent the gas pressure inside the expansion member 32 from exceeding its pressure limit and causing excessive expansion and damage, and to facilitate the removal of the sampling tube 31 by retracting the expansion member 32 and separating it from the inner wall of the outlet 22, a pressure relief hole 35 is provided on the inlet end wall of the sampling tube 31, circumferentially parallel to the vent hole 33. The pressure relief hole 35 is also located on the wall of the expansion member 32 directly opposite the sampling tube 31, penetrating the wall of the sampling tube 31, with its two ends connecting the inner cavity of the sampling tube 31 and the internal cavity of the expansion member 32, respectively. A pressure relief valve with the same structure as a one-way valve is installed inside the pressure relief hole 35, consisting of a sealing ball 36 and a spring 361. However, the preload of the pressure relief valve spring 361 is set to 1.5-2 times the preload of the one-way valve spring 361, therefore the opening pressure of the pressure relief valve is higher than that of the one-way valve. During the inflation and sealing process, the nitrogen pressure output by the air pump 34 can only open the one-way valve and cannot overcome the spring force of the pressure relief valve 361. The pressure relief valve remains closed to maintain the sealing effect.

[0036] Please continue reading. Figure 2 and Figure 3 The outlet 22 of the air valve 2 has a self-sealing structure inside, specifically including a blocking ball 37 and a tension spring 371. One end of the tension spring 371 is fixedly connected to the inner wall of the outlet 22, and the other end is fixedly connected to the blocking ball 37. The constricted end of the outlet 22 is machined with a sealing cone surface that matches the spherical surface of the blocking ball 37. The blocking ball 37 is made of stainless steel. Under normal conditions, the elastic force of the tension spring 371 pulls the blocking ball 37 tightly against the sealing cone surface, thereby sealing the outlet 22. The air inlet end of the sampling tube 31 is directly used to drive the blocking ball 37 to open. When the air inlet end of the sampling tube 31 touches the blocking ball 37 and moves it away from the outlet 22, the outlet 22 is in communication with the inner cavity of the sampling tube 31. When the air inlet end of the sampling tube 31 moves away from the blocking ball 37, the blocking ball 37 is driven again by the elastic force of the tension spring 371 to seal the outlet 22. It should be noted that, since the air inlet end of the sampling tube 31 needs to both axially contact and push the blocking ball 37 to open the valve, and also allow the gas to be tested in the outlet 22 to flow into the inner cavity of the sampling tube 31, the end face of the air inlet end of the sampling tube 31 can be set as a non-complete flat annular surface. This allows the air inlet end of the sampling tube 31 to contact the spherical surface of the blocking ball 37 and apply a pushing force when it contacts the blocking ball 37, and also connects the outlet 22 with the air inlet channel of the inner cavity of the sampling tube 31.

[0037] Please continue reading. Figure 3 and Figure 5 In this embodiment, the diameters of the two ends of the vent 33, the air outlet 22 and the pressure relief hole 35 gradually decrease along their axial direction, forming a symmetrical constriction structure that can fit with a sphere, thereby improving the sealing performance of each sealing part.

[0038] Please continue reading. Figure 3 and Figure 5 During the actual docking of this device, the inlet end of the sampling tube 31 is inserted into the outlet 22. When the expansion member 32 is fully inserted into the outlet 22, the front end face of the sampling tube 31 just contacts the spherical surface of the blocking ball 37, causing it to overcome the tension of the tension spring 371, detach from the sealing cone surface, and move into the outlet 22, thereby opening the outlet 22. At this time, the outlet 22 is directly connected to the inner cavity of the sampling tube 31 (e.g., Figure 5 (As shown), but at this time the valve of the gas cylinder is in the closed state, the gas in the cylinder will not directly leak from the outlet 22 into the inner cavity of the sampling tube 31. Then, the gas pump 34 is started to fill the inner cavity of the sampling tube 31 with nitrogen. The nitrogen enters the expansion member 32 through the vent 33, causing it to expand radially and fill the annular gap between the outer wall of the sampling tube 31 and the inner wall of the outlet 22, completing the seal. After the seal is formed, the valve of the gas cylinder is opened, and the gas flows through the valve connecting pipe → inlet 21 → outlet 22 → inner cavity of the sampling tube 31 → detection device 1. After sampling is completed, the sampling tube 31 is pulled out. First, it is confirmed that the valves of all gas cylinders to be tested are completely closed. Keeping the current insertion position of the sampling tube 31 unchanged, the gas pump 34 is switched to the suction mode to increase the negative pressure in the inner cavity of the sampling tube 31. When the suction force generated by the negative pressure exceeds the pre-tightening force of the pressure relief valve spring 361, the sealing ball 36 in the pressure relief hole 35 is pulled open, and the nitrogen in the expansion member 32 flows back to the inner cavity of the sampling tube 31 through the pressure relief hole 35. It is then pumped out by the air pump 34 to a safe outdoor area for discharge or connected to a dedicated waste gas treatment device. The expansion member 32 retracts and separates from the inner wall of the air outlet 22, releasing the radial seal between the sampling tube 31 and the air outlet 22. After the expansion member 32 has fully retracted, hold the valve body 312 and pull the sampling tube 31 outward along the axial direction to slowly pull the air inlet end of the sampling tube 31 out of the air outlet 22. During the pulling process, the end face of the air inlet end of the sampling tube 31 gradually separates from the blocking ball 37. The tension spring 371 then rebounds and pulls the blocking ball 37 to move towards the sealing cone surface. Before the sampling tube 31 is completely pulled out, the blocking ball 37 has been tightly attached to the sealing cone surface again, automatically sealing the air outlet 22 and completing the entire process of this batch verification operation.

[0039] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A batch calibration fixture for combustible gas detectors, comprising a detection device (1) and a docking device, wherein the docking device comprises a gas valve (2) and a connecting valve (3), wherein the gas valve (2) has an interconnected gas outlet (22) and a plurality of gas inlets (21), characterized in that, The connecting valve (3) includes: The sampling tube (31) has an inlet end that can extend into or out of the outlet (22), and the outlet end of the sampling tube (31) is connected to the detection end of the detection device (1) through a pipe. An expansion member (32) is provided at the air inlet end of the sampling tube (31) and is used to seal the gap between the air inlet end of the sampling tube (31) and the air outlet (22) after expansion. Vent hole (33) is provided at the air inlet end of sampling tube (31) and the vent hole (33) penetrates the tube wall of sampling tube (31). The vent hole (33) is connected to the inner cavity of expansion member (32) and sampling tube (31) respectively. A one-way valve is provided in the vent (33) to allow the gas in the inner cavity of the sampling tube (31) to flow into the expansion member (32) in one direction. An air pump (34) is connected to a sampling tube (31) via a pipe.

2. The batch calibration fixture for combustible gas detectors according to claim 1, characterized in that: The connecting valve (3) also includes a pressure relief hole (35), which is located at the air inlet end of the sampling tube (31) and penetrates the tube wall of the sampling tube (31). The pressure relief hole (35) is connected to the inner cavity of the expansion member (32) and the sampling tube (31) respectively. The pressure relief hole (35) is equipped with a pressure relief valve, which is used to allow the gas in the expansion member (32) to flow into the sampling tube (31) in one direction. The opening pressure of the pressure relief valve is greater than the opening pressure of the one-way valve.

3. The batch calibration fixture for combustible gas detectors according to claim 1, characterized in that: The air pump (34) is connected to a nitrogen source at its air inlet end; the air pump (34) is an integrated pumping and filling air pump (34).

4. The batch calibration fixture for combustible gas detectors according to claim 1, characterized in that: The inflator (32) is an airbag.

5. The batch calibration fixture for combustible gas detectors according to claim 1, characterized in that: The expansion member (32) is annular.

6. The batch calibration fixture for combustible gas detectors according to claim 2, characterized in that: Both the one-way valve and the pressure relief valve include a sealing ball (36) and a spring (361). The sealing ball (36) is used to seal the vent (33) or the pressure relief hole (35). One end of the spring (361) is fixedly connected to the sealing ball (36), and the other end is fixedly connected to the inner wall of the vent (33) or the pressure relief hole (35).

7. The batch calibration fixture for combustible gas detectors according to claim 6, characterized in that: The outlet (22) is provided with a blocking ball (37) for sealing the outlet (22). The blocking ball (37) is fixedly connected to a tension spring (371). The free end of the tension spring (371) is fixedly connected to the inner wall of the outlet (22). The air inlet end of the sampling tube (31) is used to drive the blocking ball (37) away from the outlet (22).

8. The batch calibration fixture for combustible gas detectors according to claim 7, characterized in that: The diameters of the two ends of the vent (33), the outlet (22) and the pressure relief hole (35) gradually decrease along their axial direction.

9. The batch calibration fixture for combustible gas detectors according to claim 1, characterized in that: The connecting valve (3) also includes a valve body (312), which has a through groove for accommodating the sampling tube (31); the inlet and outlet of the sampling tube (31) are respectively located outside the groove opening.

10. The batch calibration fixture for combustible gas detectors according to claim 9, characterized in that: A valve seat (313) is fixedly connected to the side of the valve body (312) near the air inlet end of the sampling tube (31). The valve seat (313) has a limiting groove that matches the outer wall of the air valve (2).

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