Tempering check valve

Abstract

The tempering check valve comprises a shell, an inlet connector and an outlet connector, the inlet connector and the outlet connector are assembled at the two ends of the shell in a sealed mode, a normally-closed inlet valve element is arranged in an inlet cavity formed by an inlet base and an inlet flow divider, and air inlet conduction and reverse blocking are achieved through the inlet valve element; a normally-open type outlet valve element is arranged in an outlet cavity formed by the outlet base and the outlet flow divider, and air inlet conduction and high-temperature tempering blocking are achieved through the outlet valve element. And a fire-retardant filtering layer assembly which is of a laminated structure in the air inlet direction and is used for blocking reverse diffusion of open fire is arranged in a fire-retardant cavity formed by the inlet flow divider, the outlet flow divider and the shell. According to the tempering check valve, safety accidents caused by use of combustible gas can be effectively avoided, the production cost of the valve can be greatly reduced, and meanwhile the safety coefficient of the tempering check valve is greatly improved.

Description

Technical Field

[0001] This invention belongs to the technical field of gas combustion or gas-use check valves, specifically a backfire check valve. Background Technology

[0002] Currently, the new materials, steel, and petrochemical industries all utilize gas combustion in their production processes. In the steel industry, over 90% of the steelmaking process involves continuous casting machines for steel production, cutting, and metallurgy. Cutting primarily employs various methods, including traditional flame cutting, coke oven gas, and hydrogen-oxygen gas for billet cutting. Metallurgy mainly involves introducing oxygen, hydrogen, or natural gas into blast furnaces. In the new materials industry, Chinese glass manufacturers utilize a variety of fuels, including natural gas, coke oven gas, hydrogen, and producer gas. In the petrochemical industry, new regenerative combustion technologies utilize regenerable chambers in heating furnaces, which use natural gas as fuel. Additionally, handheld flame torches are used in industrial manufacturing for traditional cutting of thin-walled steel plates or gas-fired cutting, commonly using natural gas, methane, and propane as fuel. Gas is also used for pressurization or depressurization, typically employing highly flammable gases.

[0003] In recent years, in response to environmental protection needs, gaseous fuels have become increasingly diversified, especially hydrogen. Hydrogen is currently a green energy source on the market, and combustion processes based on hydrogen have gradually emerged. The main process uses hydrogen as the combustion agent and oxygen as the combustion aid for industrial applications such as cutting, smelting, and heating.

[0004] Regardless of the fuel chosen, the use of gaseous gases carries inherent safety risks in existing industries due to their chemical and physical properties. For example, hydrogen combined with oxygen is prone to backfire during combustion, and this backfire cannot be prevented, potentially leading to an explosion within the factory. Similarly, natural gas combined with oxygen is also prone to backfire, which cannot be prevented, causing safety accidents and personnel hazards. Direct use of hydrogen for pressurization or depressurization carries the risk of backfire if an external fire occurs, or if impurities or static electricity are present in the pipeline, posing risks to equipment and personnel. Therefore, the use and combustion of flammable gases pose safety risks, easily causing personal injury and accidents. Thus, it is necessary to design a backfire check valve with a higher safety factor.

[0005] Patent document CN201620701227.3 discloses a non-return breathable alloy core type flame arrester for hydrogen-oxygen mixtures, hydrogen, or fuel gas. This flame arrester has a flow diversion channel inside the valve cover, a flame arresting chamber inside the valve seat, and a confluence channel inside the valve seat. Each flame arresting chamber contains a flame arresting unit. A front end cap and a rear end cap are encapsulated on the alloy core. The front end cap has a mounting hole and multiple air inlets. The mounting hole is axially oriented and contains a spring. The air inlets are radially oriented, and a non-return valve is located inside the mounting hole. The alloy core, non-return valve, front end cap, rear end cap, and spring are fastened to the valve seat by a compression nut. A gas blocking chamber is formed between the outer wall of the alloy core and the inner wall of the flame arresting chamber. A flashback blocking chamber is formed between the rear end of the front end cap and the front end of the rear end cap. The flow diversion channel, flame arresting chamber, and confluence channel are arranged sequentially and correspondingly. However, this patented technology cannot achieve dual blocking against low-temperature flashback or triple blocking against high-temperature flashback, and its safety factor still needs further improvement. Patent document CN92223811.1 discloses a dry flashback arrestor, which is installed on a combustible gas delivery pipeline or storage container to extinguish ignition sources in the backflow gas stream formed during flashback. It includes a cylindrical shell with a gas inlet and outlet, a check valve assembly between the gas inlet and outlet located within the shell, a cylindrical dry flame arrestor, and a relief valve assembly located at one end of the shell. By connecting the check valve assembly and the relief valve assembly, the flame arrestor located inside the shell and surrounding the check valve assembly performs a dual flame arresting function. However, this patented technology cannot achieve dual blocking against low-temperature flashback or triple blocking against high-temperature flashback, and its safety factor still needs further improvement. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a low-cost and safer backfire check valve. This backfire check valve can effectively avoid safety accidents caused by the use of flammable gases and can significantly reduce the production cost of valve components, while greatly improving the safety factor of the backfire check valve.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a backfire check valve, comprising a shell and an inlet connector and an outlet connector sealed at both ends of the shell. One side of the inlet connector has an axial air inlet hole, and the other side of the inlet connector has an axially enlarged mounting cavity communicating with the air inlet hole. An inlet base is provided within the enlarged mounting cavity and is limited and pressed and fixed by an inlet diverter located on one side of the inlet base. A normally closed inlet valve core is provided within the inlet cavity formed by the inlet base and the inlet diverter, and the inlet valve core enables air intake conduction and reverse blocking. The outlet connector has an axial air outlet on one side and an axial enlarged mounting cavity communicating with the air outlet on the other side. The enlarged mounting cavity contains an outlet base, which is fixed by an outlet diverter located on one side of the outlet base. The outlet cavity formed by the outlet base and the outlet diverter contains a normally open outlet valve core, which enables air intake and high-temperature backfire prevention. The flame arrestor cavity formed by the inlet diverter, the outlet diverter and the shell contains a flame arrestor filter layer assembly with a stacked structure along the air intake direction to prevent the reverse diffusion of open flame.

[0008] Further defined, the inlet base is installed on the limiting step inside the inlet connector. An axial guide hole is provided in the middle of one side of the inlet base, corresponding to the air inlet hole inside the inlet connector. Multiple axial inlet guide holes communicating with the air inlet hole inside the inlet connector are distributed circumferentially on the inlet base outside the guide hole. A conical valve cavity with a smaller inner diameter and larger outer diameter is provided on the other side of the inlet base, communicating with the inlet guide holes. The inlet distributor is a variable-diameter cylindrical structure. One end of the inlet distributor is tightly fitted to the inlet base. The middle of the inlet distributor is narrowed by the variable-diameter step, forming an inlet valve core mounting cavity on the other side of the inlet distributor. A guide hole is provided on the variable-diameter step of the inlet distributor, and... The guide hole enables communication between the inlet cavity and the flame arrestor cavity. The other end of the inlet diverter is tightly fitted with the blind end of the outlet diverter. The valve body of the inlet valve core is a conical structure that matches the conical structure valve cavity inside the inlet base. By pressing the valve body into the valve cavity, i.e., when the inlet valve core is closed, a double seal is achieved at the inlet guide hole and at the junction of the valve body and the valve core cone. One side of the valve body is provided with an axial guide rod that is slidably installed in the guide hole of the inlet base. The other side of the valve body is provided with a guide base that is axially slidably fitted with the inlet valve core mounting cavity inside the inlet diverter. The inside of the guide base is provided with a groove and a spring is installed in the groove. The other end of the spring is tightly fitted with the blind end of the outlet diverter.

[0009] Further specified, the outlet base is installed on the limiting step inside the outlet connector. An axial guide hole is provided in the middle of one side of the outlet base, corresponding to the air outlet hole inside the outlet connector. Multiple axial outlet guide holes communicating with the air outlet hole inside the outlet connector are distributed circumferentially on the outlet base outside the guide hole. A conical valve cavity with a smaller inner diameter and larger outer diameter, communicating with the outlet guide holes, is provided on the other side of the outlet base. The outlet diverter is a one-end sealed variable-diameter cylindrical structure. The open end of the outlet diverter is tightly fitted to the outlet base. The middle of the outlet diverter is narrowed by the variable-diameter step, forming an outlet valve core mounting cavity on the other side of the outlet diverter. Guide holes are provided on the variable-diameter step of the outlet diverter or on the cylindrical body on the open side of the outlet diverter, and the communication between the outlet cavity and the flame arrestor cavity is achieved through these guide holes. The blind end of the outlet diverter is tightly fitted to the constricted end of the inlet diverter; the valve body of the outlet valve core is a conical structure that matches the conical structure valve cavity inside the outlet base. By pressing the valve body into the valve cavity, i.e., when the outlet valve core is closed, a double seal is achieved at the outlet guide hole and at the junction of the valve body and the valve core cone. An axial guide rod is provided on one side of the valve body, and the guide rod slides in fit with the guide hole of the outlet base. When the outlet valve core is normally open, the end of the outlet valve core guide rod is fixed in the guide hole of the outlet base by soldering. The outlet valve core is closed by the hot melting of the solder under the high temperature flue gas tempering state. A guide base is provided on the other side of the valve body, which slides axially in fit with the outlet valve core mounting cavity inside the outlet diverter. A spring is installed at the end of the guide base, and the other end of the spring is tightly fitted to the blind end of the outlet diverter.

[0010] Further defined, the variable diameter step and constricted side cylinder of the inlet separator, the variable diameter step and constricted side cylinder of the outlet separator, together with the shell, form a flame-arresting cavity. The annular flame-arresting filter layer assembly is sleeved on the constricted side cylinders of the inlet separator and the outlet separator, and the two ends of the flame-arresting filter layer assembly are respectively pressed and limited by the variable diameter step of the inlet separator and the variable diameter step of the outlet separator. The outer circumference of the flame-arresting filter layer assembly is in contact with the inside of the shell. The flame-arresting filter layer assembly is composed of multiple filter discs with different filtration precision and thickness in a stacked structure.

[0011] Furthermore, in the flame-retardant filter layer assembly, the thickness of the multi-layer filter discs increases sequentially along the air intake direction, and the filtration accuracy of the multi-layer filter discs decreases sequentially along the air intake direction.

[0012] Furthermore, the filter layer of the filter disc is made of ceramic sintered mesh or stainless steel powder sintered mesh.

[0013] Further specified, the inlet connector and outlet connector are respectively sealed and screwed to both ends of the housing or interference-fitted and sealed to both ends of the housing.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The backfire check valve of the present invention has a one-way valve function. A one-way inlet valve core is provided at the inlet base inside the valve, which can effectively block the reverse flow of gas.

[0015] 2. The backfire check valve of the present invention has a high-temperature backfire prevention and shut-off function, which can effectively block high-temperature flames or high-temperature gases under backfire.

[0016] 3. The backfire check valve of this invention has a flame-arresting function. The valve assembly contains a layered flame-arresting filter layer assembly. The filtration accuracy of the flame-arresting filter layer assembly decreases sequentially along the air inlet direction and is installed inside the housing to effectively block the reverse diffusion of open flame, thereby ensuring the safety of the equipment's gas supply. The filter layer in the flame-arresting filter layer assembly uses ceramic sintered mesh or stainless steel powder sintered mesh, which can more effectively improve the safety performance of the valve.

[0017] 4. The backfire check valve of the present invention is suitable for flame arrest under high temperature and high pressure conditions. The valve is equipped with a stacked flame arrestor filter layer assembly and a temperature cut-off solder structure at the outlet. The gas can effectively block the flame even under high temperature and high pressure conditions, effectively ensuring the safety of the gas used in the equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure under normal ventilation conditions of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the low-temperature flue gas tempering state of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of the present invention under high-temperature flue gas tempering state.

[0021] In the diagram: 1-Inlet connector; 2-Inlet base; 3-Housing; 4-Inlet diverter; 5-Inlet valve core; 6-Flame arrestor filter assembly; 7-Outlet diverter; 8-Outlet base; 9-Outlet valve core; 10-Outlet connector; 11-Spring. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figures 1-3A backfire check valve includes a housing 3 and an inlet connector 1 and an outlet connector 10 sealed at both ends of the housing 3. One side of the inlet connector 1 has an axial air inlet hole, and the other side has an axially enlarged mounting cavity communicating with the air inlet hole. An inlet base 2 is provided within the enlarged mounting cavity and is limited and pressed by an inlet diverter 4 located on one side of the inlet base 2. A normally closed inlet valve core 5 is provided within the inlet cavity formed by the inlet base 2 and the inlet diverter 4, enabling air intake and reverse blocking. The outlet connector 10 has one side... An axial air outlet is provided, and an axial enlarged hole mounting cavity communicating with the air outlet is provided on the other side of the outlet connector 10. An outlet base 8 is provided in the enlarged hole mounting cavity and is limited and pressed and fixed by an outlet diverter 7 provided on one side of the outlet base 8. A normally open outlet valve core 9 is provided in the outlet cavity formed by the outlet base 8 and the outlet diverter 7, and the inlet air conduction and high temperature backfire blocking are realized through the outlet valve core 9. The flame arresting cavity formed by the inlet diverter 4 and the outlet diverter 7 and the housing 3 is provided with a flame arresting filter layer assembly 6 with a stacked structure along the air intake direction for blocking the reverse diffusion of open flame.

[0024] The inlet base 2 of this invention is installed on the limiting step inside the inlet connector 1. An axial guide hole is provided in the middle of one side of the inlet base 2, corresponding to the air inlet hole inside the inlet connector 1. Multiple axial inlet guide holes communicating with the air inlet hole inside the inlet connector 1 are distributed circumferentially on the inlet base outside the guide hole. A conical valve cavity with a smaller inner diameter and larger outer diameter is provided on the other side of the inlet base 2, communicating with the inlet guide holes. The inlet diverter 4 is a variable diameter cylindrical structure. One end of the inlet diverter 4 is tightly fitted to the inlet base 2. The middle of the inlet diverter 4 is narrowed by the variable diameter step, forming an inlet valve core mounting cavity on the other side of the inlet diverter 4. A guide hole is provided on the variable diameter step of the inlet diverter 4, and the guide hole... The flow orifice enables communication between the inlet cavity and the flame arrestor cavity. The other end of the inlet diverter 4 is tightly fitted with the blind end of the outlet diverter 7. The valve body of the inlet valve core 5 is a conical structure that matches the conical structure valve cavity inside the inlet base 2. By pressing the valve body into the valve cavity, i.e., when the inlet valve core 5 is closed, a double seal is achieved at the inlet guide hole and at the junction of the valve body and the valve core cone. One side of the valve body is provided with an axial guide rod, which is slidably installed in the guide hole of the inlet base 2. The other side of the valve body is provided with a guide base that is axially slidably fitted with the inlet valve core mounting cavity inside the inlet diverter 4. The inside of the guide base is provided with a groove, and a spring 11 is installed in the groove. The other end of the spring 11 is tightly fitted with the blind end of the outlet diverter 7.

[0025] The outlet base 8 of this invention is installed on the limiting step inside the outlet connector 10. An axial guide hole is provided in the middle of one side of the outlet base 8, opposite to the air outlet hole inside the outlet connector 10. Multiple axial outlet guide holes communicating with the air outlet hole inside the outlet connector 10 are distributed circumferentially on the outlet base 8 outside the guide hole. A conical valve cavity with a smaller inner diameter and a larger outer diameter is provided on the other side of the outlet base 8, communicating with the outlet guide holes. The outlet diverter 7 is a variable-diameter cylindrical structure sealed at one end. The open end of the outlet diverter 7 is tightly fitted to the outlet base 8. The middle of the outlet diverter 7 is narrowed by the variable-diameter step, forming an outlet valve core mounting cavity on the other side of the outlet diverter 7. A guide hole is provided on the variable-diameter step of the outlet diverter 7 or on the cylindrical body on the open side of the outlet diverter 7, and the outlet cavity and flame arrestor cavity are connected through this guide hole. The blind end of the outlet diverter 7 is tightly fitted with the constricted end of the inlet diverter 4; the valve body of the outlet valve core 9 is a conical structure that matches the conical structure valve cavity inside the outlet base 8. By pressing the valve body into the valve cavity, i.e., when the outlet valve core 9 is closed, a double seal is achieved at the outlet guide hole and at the junction of the valve body and the valve core cone. An axial guide rod is provided on one side of the valve body, and the guide rod slides in fit with the guide hole of the outlet base 10. When the outlet valve core 9 is normally open, the end of the guide rod of the outlet valve core 9 is fixed in the guide hole of the outlet base 8 by soldering. The outlet valve core 9 is closed by the hot melting of the solder under the high temperature flue gas tempering state. A guide base is provided on the other side of the valve body, which slides axially in fit with the outlet valve core mounting cavity inside the outlet diverter 7. A spring 11 is installed at the end of the guide base, and the other end of the spring 11 is tightly fitted with the blind end of the outlet diverter 7.

[0026] The variable diameter step and constricted side cylinder of the inlet separator 4 and the variable diameter step and constricted side cylinder of the outlet separator 7, together with the shell 3, form a flame-arresting cavity. The annular flame-arresting filter layer assembly 6 is sleeved on the constricted side cylinder of the inlet separator 4 and the outlet separator 7, and the two ends of the flame-arresting filter layer assembly 6 are respectively pressed and limited by the variable diameter step of the inlet separator 4 and the variable diameter step of the outlet separator 7. The outer circumference of the flame-arresting filter layer assembly 6 is in contact with the inside of the shell 3. The flame-arresting filter layer assembly 6 is composed of multiple filter discs with different filtration precision and thickness in a stacked structure. The thickness of the multiple filter discs in the flame-arresting filter layer assembly 6 increases sequentially along the air intake direction, and the filtration precision of the multiple filter discs decreases sequentially along the air intake direction. The filter layer of the filter disc is made of ceramic sintered mesh or stainless steel powder sintered mesh.

[0027] The inlet connector 1 and outlet connector 10 of the present invention are respectively sealed and screwed to both ends of the housing 3 or installed at both ends of the housing 3 by interference fit.

[0028] Please see Figure 1Backfire check valve open state: combustible gas pushes open the normally closed inlet valve core, combustible gas enters the inlet chamber through the inlet guide hole, and then enters the outlet chamber through the guide hole on the inlet distributor reducer step, the flame arrestor chamber and the guide hole on the inlet distributor opening side cylinder. Then the combustible gas in the outlet chamber enters the outlet connector outlet hole through the normally open outlet valve core and the outlet guide hole. Please see Figure 2 In the low-temperature closed state of the flashback check valve: the combustible gas is cut off, the inlet valve core enters the normally closed state, which can effectively block the reverse flow of gas. The low-temperature flashback flue gas (which does not reach the melting temperature of tin) enters the outlet chamber through the normally open outlet valve core and the outlet guide hole. The low-temperature flashback flue gas effectively blocks the reverse diffusion of open flame through the flame arrestor filter layer assembly, thereby effectively improving the safety of the valve and ensuring the gas safety of the equipment. The flashback check valve for low-temperature flashback flue gas can achieve double flame arrest at the flame arrestor filter layer assembly and the inlet valve core. Please see Figure 3 The backfire check valve in high-temperature closed state: combustible gas is cut off, which can effectively block the reverse flow of gas. The inlet valve core enters the normally closed state. The backfire high-temperature flue gas (reaching the tin melting temperature) melts the tin, causing the outlet valve core to enter the closed state. It has a high-temperature backfire prevention and cut-off function, which can effectively block the high-temperature flame or high-temperature gas under backfire. At the same time, it can effectively block the reverse diffusion of open flame through the flame arrestor filter layer assembly, thereby effectively improving the safety of valve components and ensuring the gas safety of equipment. For backfire high-temperature flue gas, the backfire check valve can achieve triple flame arrest at the outlet valve core, the flame arrestor filter layer assembly and the inlet valve core.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A backfire check valve, characterized in that... The device includes a housing and sealing fittings at both ends of the housing, including inlet and outlet connectors. One side of the inlet connector has an axial air inlet hole, and the other side has an axially enlarged mounting cavity communicating with the air inlet hole. An inlet base is located within this cavity and is secured by an inlet distributor positioned on one side of the inlet base. A normally closed inlet valve core is located within the inlet cavity formed by the inlet base and the inlet distributor, enabling airflow and preventing reverse propagation. One side of the outlet connector has an axial air outlet hole, and the other side has an axially enlarged mounting cavity communicating with the outlet hole. An outlet base is located within this cavity and is secured by an outlet distributor positioned on one side of the outlet base. A normally open outlet valve core is located within the outlet cavity formed by the outlet base and the outlet distributor, enabling airflow and preventing high-temperature flashback. The flame-arresting cavity formed by the inlet and outlet distributors and the housing contains a stacked flame-arresting filter assembly along the airflow direction to prevent the reverse propagation of open flame.

2. The backfire check valve according to claim 1, characterized in that: The inlet base is installed on the limiting step inside the inlet connector. An axial guide hole, corresponding to the air inlet hole inside the inlet connector, is located in the middle of one side of the inlet base. Multiple axial inlet guide holes, communicating with the air inlet hole inside the inlet connector, are distributed circumferentially on the inlet base outside this guide hole. A conical valve cavity, with a smaller inner diameter and larger outer diameter, is located on the other side of the inlet base, communicating with the inlet guide holes. The inlet distributor is a variable-diameter cylindrical structure. One end of the inlet distributor is tightly fitted to the inlet base. The middle of the inlet distributor narrows through the variable-diameter step, forming an inlet valve core mounting cavity on the other side. A guide hole is located on the variable-diameter step of the inlet distributor, and flow is passed through this guide hole. The inlet cavity and the flame arrestor cavity are connected, and the other end of the inlet diverter is tightly fitted with the blind end of the outlet diverter. The valve body of the inlet valve core is a conical structure that matches the conical structure valve cavity inside the inlet base. By pressing the valve body into the valve cavity, i.e., when the inlet valve core is closed, a double seal is achieved at the inlet guide hole and at the junction of the valve body and the valve core cone. One side of the valve body is provided with an axial guide rod, which is slidably installed in the guide hole of the inlet base. The other side of the valve body is provided with a guide base that is axially slidably fitted with the inlet valve core mounting cavity inside the inlet diverter. The inside of the guide base is provided with a groove, and a spring is installed in the groove. The other end of the spring is tightly fitted with the blind end of the outlet diverter.

3. A backfire check valve according to claim 1, characterized in that: The outlet base is installed on the limiting step inside the outlet connector. An axial guide hole is provided in the middle of one side of the outlet base, corresponding to the air outlet hole inside the outlet connector. Multiple axial outlet guide holes communicating with the air outlet hole inside the outlet connector are distributed circumferentially on the outlet base outside the guide hole. A conical valve cavity with a smaller inner diameter and larger outer diameter, communicating with the outlet guide holes, is provided on the other side of the outlet base. The outlet diverter is a one-end sealed variable-diameter cylindrical structure. The open end of the outlet diverter is tightly fitted to the outlet base. The middle of the outlet diverter narrows through the variable-diameter step, forming an outlet valve core mounting cavity on the other side of the outlet diverter. A guide hole is provided on the variable-diameter step or the cylindrical body on the open side of the outlet diverter, through which the outlet cavity and the flame arrestor cavity are connected. The blind end of the valve is tightly fitted to the constricted end of the inlet diverter; the valve body of the outlet valve core is a conical structure that matches the conical structure valve cavity inside the outlet base. By pressing the valve body into the valve cavity, i.e., when the outlet valve core is closed, a double seal is achieved at the outlet guide hole and at the junction of the valve body and the valve core cone. One side of the valve body is provided with an axial guide rod, which slides with the guide hole of the outlet base. When the outlet valve core is normally open, the end of the outlet valve core guide rod is fixed in the guide hole of the outlet base by soldering. The outlet valve core is closed by the hot melting of the solder under the high temperature flue gas tempering state. The other side of the valve body is provided with a guide base that slides axially with the outlet valve core mounting cavity inside the outlet diverter. A spring is installed at the end of the guide base, and the other end of the spring is tightly fitted to the blind end of the outlet diverter.

4. A backfire check valve according to claim 1, characterized in that: The variable diameter step and constricted side cylinder of the inlet separator, the variable diameter step and constricted side cylinder of the outlet separator, together with the shell, form a flame-arresting cavity. The annular flame-arresting filter layer assembly is sleeved on the constricted side cylinder of the inlet separator and the outlet separator, and the two ends of the flame-arresting filter layer assembly are respectively pressed and limited by the variable diameter step of the inlet separator and the variable diameter step of the outlet separator. The outer circumference of the flame-arresting filter layer assembly is in contact with the inside of the shell. The flame-arresting filter layer assembly is composed of multiple filter discs with different filtration precision and thickness in a stacked structure.

5. A backfire check valve according to claim 1, characterized in that: In the flame-retardant filter layer assembly, the thickness of the multi-layer filter discs increases sequentially along the air intake direction, and the filtration accuracy of the multi-layer filter discs decreases sequentially along the air intake direction.

6. A backfire check valve according to claim 4 or 5, characterized in that: The filter layer of the filter disc is made of ceramic sintered mesh or stainless steel powder sintered mesh.

7. A backfire check valve according to claim 1, characterized in that: The inlet and outlet connectors are respectively sealed and screwed to both ends of the housing or installed at both ends of the housing with an interference fit.

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