A switching device for fire extinguishing agent

Abstract

The present invention belongs to the technical field of fire-fighting equipment, and specifically relates to a fire extinguishing agent switching device. It mainly includes an outer cylinder, an inner cylinder, a liquid phase pipeline, and a foam branch. The outer cylinder is divided into a front and rear separation cylinder body, which are connected by a soft telescopic tube. The outer cylinder stores foam fire extinguishing agent. The inner cylinder is inserted from the rear end opening of the outer cylinder. The rear separation cylinder body can slide back and forth on the outer wall surface of the inner cylinder. The liquid phase pipeline is inserted from the outer cylinder and the inner cylinder respectively. The liquid phase pipeline can be adjusted by moving the subsequent separation cylinder body so that the two liquid phase pipelines can be connected and separated. The foam branch is arranged between the outer cylinder and its liquid phase pipeline, and a valve is provided on the liquid phase pipeline. The inner cylinder is also provided with an air inlet connected to an external air pump. The foam fire extinguishing agent in the outer cylinder can instantly generate foam for emergency fire extinguishing after switching. The present invention facilitates firefighters to flexibly switch fire extinguishing agents according to the type of fire source and the type of surrounding combustible materials at the fire scene when extinguishing a fire, and to carry out fire extinguishing and rescue operations.

Description

Technical Field

[0001] The invention belongs to the technical field of fire-fighting equipment, and in particular relates to a switching device for a fire-extinguishing agent. Background Art

[0002] In recent years, the lithium battery industry has flourished, with numerous lithium batteries being used in emerging technology industries such as electric passenger vehicles and energy storage power stations, contributing to the global economy's transition to a low-carbon, greener economy. With the booming lithium battery industry, fire safety has become a major bottleneck hindering its development. Lithium batteries are prone to thermal runaway under external shocks, heat, overcharging, and other factors. The progression of thermal runaway is often accompanied by large amounts of smoke and heat emissions, which can easily trigger widespread combustion. Lithium battery fires are also difficult to extinguish and pose a high risk of re-ignition. The international standard for extinguishing lithium battery fires is to use large amounts of water for cooling. Existing research indicates that compressed air foam can also be effective in extinguishing lithium battery fires. Using compressed air foam is a relatively water-efficient firefighting method, particularly for large fires or those with limited water supply. Therefore, the flexible switching between water and foam fire extinguishing agents is crucial for improving the efficiency of lithium battery fire fighting.

[0003] Regarding fire extinguishing agent switching devices, the primary focus is on water / foam switching. Patent application number: 202322592099.6 provides two fire extinguishing agent cartridges and two different nozzles, enabling switching between foam and water through pipeline switching. Patent application number: 201320020284.1 provides a method for using negative pressure suction foaming generated by a jet. Closing the negative pressure suction valve enables water jetting, thereby switching between two fire extinguishing agents. Existing solutions require two fire extinguishing agent nozzles and separate piping systems, or require foaming through negative pressure suction generated by a foam mixture jet. This results in a complex system and poor foaming effectiveness, with foam quality often significantly impacting firefighting effectiveness. Therefore, to address these issues, the present invention provides a compressed air-based positive pressure foam / water switching device. This device shares a common piping system, reducing system complexity and improving foaming effectiveness, thereby increasing the efficiency of firefighting personnel in complex firefighting scenarios. Summary of the Invention

[0004] The object of the present invention is to provide a switching device which is easy to operate and can quickly switch between water and foam fire extinguishing agents.

[0005] The fire extinguishing agent switching device provided by the present invention comprises an outer cylinder, an inner cylinder, a liquid phase main pipeline, a foam branch pipeline, a liquid phase rear pipeline and a fixing bracket;

[0006] The outer cylinder is closed at the front end and open at the rear end, and is divided into a front and rear separate cylinder body. The front and rear separate cylinder bodies are connected by a soft telescopic tube. The distance between the front and rear separate cylinder bodies can be adjusted as the soft telescopic tube is extended and contracted. The outer cylinder contains a foam fire extinguishing agent.

[0007] The inner cylinder is inserted into the rear end opening of the outer cylinder in a sealed manner, and the rear end of the inner cylinder is exposed from the outer cylinder; the inner cavity of the inner cylinder and the inner cavity of the outer cylinder are connected; the rear separation cylinder can slide back and forth on the outer wall surface of the inner cylinder;

[0008] The liquid phase main line is inserted into the outer cylinder from the front end of the front separation cylinder and is fixedly connected to the front separation cylinder; the liquid phase rear line is inserted from the rear end of the inner cylinder and is fixedly connected to the inner cylinder; the external port of the liquid phase main line is connected to the fire sprinkler, and the external port of the liquid phase rear line is connected to the external water pump;

[0009] A flexible telescopic tube is provided in the middle section of the liquid phase main line to adjust its length; the internal port of the liquid phase main line and the internal port of the liquid phase rear line (i.e., the port at one end inside the outer cylinder) are positioned opposite each other, and the internal ports can be connected and separated by the extension and contraction of the liquid phase main line;

[0010] The rear section of the liquid phase main line at the flexible telescopic tube serves as a movable line and is fixedly connected to the inner side of the rear separation cylinder of the outer cylinder via a bracket. The movement of the rear separation cylinder drives the expansion and contraction of the liquid phase main line, thereby controlling the docking and separation of the liquid phase main line and the liquid phase rear line. When the flexible telescopic tube is in the expanded state (i.e., the distance between the front and rear separation cylinders is at its maximum), the liquid phase main line and the liquid phase rear line are in a sealed docking state.

[0011] One end of the foam branch is arranged at the front end of the front separation cylinder of the outer cylinder and communicates with the inner cavity of the outer cylinder; the other end of the foam branch is connected to and passes through the liquid phase main line;

[0012] The liquid phase main line is provided with an on-off valve; the on-off valve is located after the connection point between the foam branch line and the liquid phase main line (that is, between the connection point between the foam branch line and the liquid phase main line and the outer cylinder);

[0013] An air inlet is also provided at the rear end of the inner cylinder, and the air inlet is connected to an external gas supply device;

[0014] The fixed bracket is used to support the entire switching device and is divided into front and rear support legs. The front support leg is fixedly connected to the front separation cylinder of the outer cylinder, and the rear support leg is fixedly connected to the rear end of the inner cylinder; the fixed bracket is fixed to the ground or platform.

[0015] In the present invention, a metal mesh screen for foaming is provided in the outer cylinder and / or the inner cylinder, between the air inlet and the foam branch, and a through hole is provided in the center of the metal mesh screen for the liquid phase main line to pass through.

[0016] In the present invention, the metal mesh screen is replaceable and can be provided in plurality. Metal mesh screens with different mesh specifications can be provided according to the foaming requirements.

[0017] In the present invention, the internal port of the liquid phase main line is in a bell-mouth shape, and a sealing silicone is provided on the inner side wall of the bell-mouth. After the internal port of the liquid phase rear line is inserted into the internal port of the liquid phase main line, it can fit tightly on the sealing silicone, which can further improve the sealing effect of the liquid phase; because of the expanded design of the bell-mouth-shaped pipe mouth, it is convenient for the liquid phase rear line to automatically correct its alignment when docking, and it can be docked to the liquid phase main line more accurately.

[0018] In the present invention, the switch valve is an electrically controlled valve, and is further provided with a linkage control switch. The linkage control switch is connected to the switch valve through a main control board arranged outside the outer cylinder. The linkage control switch can control the switch valve to open and close automatically.

[0019] In the present invention, the linkage control switch is a light sensor, which is embedded on the outer surface of the inner tube and located near the edge of the rear separation cylinder of the outer tube, and is connected to the main control board outside the outer tube through a line;

[0020] When the rear separation cylinder is pulled backward, the liquid phase main pipeline and the liquid phase rear pipeline are separated, and the rear separation cylinder blocks the light sensor. The light sensor is stimulated to send a signal to the main control board, and the main control board controls the electric control valve to close. When the rear separation cylinder is pushed forward, the rear separation cylinder leaves the light sensor, and the main control board controls the electric control valve to open.

[0021] This linkage control makes it easier for firefighters to speed up operations and achieve quick switching in one step.

[0022] In the present invention, a handle is provided on the rear separation cylinder for facilitating pulling the rear separation cylinder.

[0023] In the present invention, there are a plurality of air inlets which are arranged around the surface of the outer cylinder at equal intervals.

[0024] In the present invention, the soft telescopic tube adopts a conventional plastic metal telescopic tube on the market.

[0025] When the present invention is used, the device is placed near a fire source, the liquid phase rear pipeline is connected to an external fire water source through a hose, and the liquid phase main pipeline is connected to a conventional fire sprinkler through a hose; the rear separation cylinder is pulled to the end, the liquid phase main pipeline and the liquid phase rear pipeline are sealed and connected, the fire sprinkler valve is opened, and the fire water source is directly sprayed out from the liquid phase rear pipeline through the liquid phase main pipeline and the fire sprinkler to perform water-based fire extinguishing;

[0026] When the fire source cannot be extinguished by water and requires foam extinguishing, the fire extinguishing agent needs to be switched. At this time, the rear end needs to supply a foam mixture. The foam mixture enters the outer cylinder through the liquid phase rear pipeline, and is mixed with the compressed air entering the air inlet in the outer cylinder, thereby foaming through the metal mesh screen. Under the continuous push of the compressed air and the mixture, the foam mixture flows through the foam branch pipe to the liquid phase main pipeline to carry out foam fire extinguishing.

[0027] In addition, there is a pre-installed foam fire extinguishing agent in the outer cylinder of this device. In an emergency situation, such as when using water-based fire extinguishing, firefighters suddenly find that there are special flammable materials on the scene that cannot be extinguished by water-based fire extinguishing. They can close the switch valve on the liquid phase main line, push the rear separation cylinder forward, separate the liquid phase main line and the liquid phase rear line, and water directly enters the outer cylinder and the inner cylinder, and mixes with the foam fire extinguishing agent prefabricated in the outer cylinder; open the external gas supply device, and inject compressed gas into the inner cylinder. The gas blows the foam mixed liquid in the outer cylinder and the inner cylinder to surge, and passes through the internal metal mesh screen for full foaming. Then, under the blowing of gas, the foamed foam fire extinguishing liquid flows to the front end of the liquid phase main line through the foam branch; open the fire sprinkler valve, and the foam fire extinguishing liquid is sprayed out from the fire sprinkler for temporary emergency foam fire extinguishing, which buys time for subsequent replacement of the well-proportioned foam mixture.

[0028] In addition, the device can also be used to conduct fire extinguishing efficiency experiments of multiple types of fire extinguishing agents within the laboratory, improving the efficiency when switching fire extinguishing agents. The metal mesh screen inside the device can improve the foaming effect, avoiding the installation of traditional foaming devices, and effectively improving the system's integration.

[0029] The present invention facilitates firefighters to flexibly switch fire extinguishing agents according to the type of fire source and surrounding combustible materials at the fire scene when extinguishing a fire, so as to carry out fire extinguishing and rescue work. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0031] Figure 2 It is a schematic diagram of the internal structure of the present invention.

[0032] Figure 3 This is a schematic diagram of the interface between the liquid phase main pipeline and the liquid phase rear pipeline.

[0033] Figure 4 Schematic diagram of the sealing rubber ring at the opening position of the inner and outer cylinders.

[0034] The numbers in the figure are: 1 is the outer cylinder, 2 is the inner cylinder, 3 is the liquid phase main line, 4 is the front separation cylinder, 5 is the rear separation cylinder, 6 is the plastic metal telescopic tube, 7 is the liquid phase rear pipeline, 8 is the foam branch, 9 is the fixed bracket, 10 is the mobile pipeline, 11 is the inner supporting connecting rod, 12 is the switch valve, 13 is the air inlet, 14 is the metal mesh screen, and 15 is the handle. DETAILED DESCRIPTION

[0035] The fire extinguishing agent switching device of the present invention includes an outer cylinder 1, an inner cylinder 2, a liquid phase main line 3, a liquid phase rear line 7, a foam branch line 8, and a fixed bracket; the outer cylinder 1, the inner cylinder 2, the liquid phase main line 3, the liquid phase rear line 7, the foam branch line 8, and the fixed bracket 9 can all be made of stainless steel (or high-strength plastic).

[0036] The outer cylinder 1 is cylindrical, with a closed front end and an open rear end, and is divided into a front separation cylinder 4 and a rear separation cylinder 5. The front and rear separation cylinders are connected by a conventional plastic metal telescopic tube 6 on the market. The distance between the front and rear separation cylinders can be adjusted as the plastic metal telescopic tube 6 expands and contracts. A certain amount of foam fire extinguishing agent is stored in the outer cylinder 1.

[0037] The inner cylinder 2 is cylindrical, and the inner cylinder 2 is inserted from the rear end opening of the outer cylinder 1 and fits tightly against the inner side wall of the rear separation cylinder 5 of the outer cylinder 1. There is a large contact surface between the inner and outer cylinders. In order to ensure that the contact surfaces of the two still have a good sealing effect during movement, sealing rubber rings are provided at the opening positions of the inner and outer cylinders. The cross section of the sealing rubber ring can be designed to be a right triangle, and the contact sliding surfaces of the inner and outer side walls of the outer cylinder 1 and the inner cylinder 2 are provided with waterproof grease to ensure that the rear separation cylinder 5 can slide smoothly back and forth on the outer side wall surface of the inner cylinder under waterproof conditions; the rear end of the inner cylinder 2 is exposed to the outer cylinder 1; the inner cavity of the inner cylinder 2 is connected to the inner cavity of the outer cylinder 1; the specific method is shown in FIG. Figure 4 As shown;

[0038] The liquid phase main line 3 is inserted into the outer cylinder 1 from the front end face of the front separation cylinder 4 and is sealed and fixed by welding; the liquid phase rear line 7 is inserted from the rear end face of the inner cylinder 2 and is also sealed and fixed by welding; the external port of the liquid phase main line 3 is connected to a conventional fire sprinkler, and the external port of the liquid phase rear line 7 is connected to an external water pump;

[0039] A small-sized plastic metal telescopic tube 6 is also provided in the middle section of the liquid phase main line 3 to adjust the length of the liquid phase main line 3. The internal port of the liquid phase main line 3 and the internal port of the liquid phase rear line 7 (i.e., the port at one end inside the outer cylinder) are positioned opposite each other, and the two internal ports can be connected and separated by the extension and contraction of the liquid phase main line 3.

[0040] The internal port of the liquid phase main line 3 is in a bell-mouth shape, and a sealing silicone is provided on the inner wall of the bell-mouth. After the internal port of the liquid phase rear line 7 is inserted into the internal port of the liquid phase main line 3, it can fit tightly on the sealing silicone. Due to the expanded bell-mouth-shaped pipe opening design, the liquid phase rear line can automatically correct its position when docking, and dock more accurately with the liquid phase main line. Figure 3 shown.

[0041] In addition, the internal port of the liquid phase rear pipeline 7 can also be designed to be a contraction mouth shape that matches the bell mouth shape, which can increase the port contact area and improve the sealing and waterproof effect.

[0042] The liquid-phase main line 3, at the rear section of the plastic metal telescopic tube 6, serves as a movable line 10, which is fixedly connected to the inner side of the rear separation cylinder 5 of the outer cylinder 1 via several internal supporting connecting rods 11. Movement of the rear separation cylinder 5 thereby drives the movable line 10 to move, i.e., to extend and retract the liquid-phase main line 3, thereby controlling the connection and separation between the liquid-phase main line 3 and the liquid-phase rear line 7. When the plastic metal telescopic tube 6 is in the expanded state (i.e., the distance between the front and rear separation cylinders is at its maximum), the liquid-phase main line 3 is in its longest state and can be sealed and connected to the liquid-phase rear line 7.

[0043] One end of the foam branch 8 is arranged at the front end of the front separation cylinder 4 of the outer cylinder 1 and communicates with the inner cavity of the outer cylinder 1; the other end of the foam branch 8 is connected to and passes through the front end of the liquid phase main line 3;

[0044] The liquid phase main line 3 is provided with an on-off valve 12; the on-off valve 12 is located behind the connection point between the foam branch line 8 and the liquid phase main line 3, that is, between the connection point between the foam branch line 8 and the liquid phase main line 3 and the outer cylinder; when the on-off valve 12 is closed, the liquid can flow from the rear end of the liquid phase main line 3 through the foam branch line 8 to the external port of the liquid phase main line 3;

[0045] An air inlet 13 is also provided at the rear end of the inner cylinder 2. The air inlet 13 is connected to an air pump of an external gas supply device via a hose to provide high-pressure compressed gas injection. There are four air inlets, which are arranged at equal intervals around the cylindrical surface of the outer cylinder and are located after the connection point between the liquid phase main pipeline 3 and the liquid phase rear pipeline 7. In this way, gas can enter the outer cylinder 1 from all angles, which helps to improve the uniformity of foaming. The number of air inlets required can be flexibly selected according to the foam multiple required on site. If high-expansion foam is required, the air inlets can be fully opened for air supply, and vice versa. When necessary, the air inlets can also serve as liquid inlets for injecting foam concentrate to ensure temporary emergency foam supply.

[0046] In the inner cylinder 2, a circular metal mesh screen 14 for foaming is provided in front of the connection point between the liquid phase main line 3 and the liquid phase rear line 7. A through hole is provided in the center of the metal mesh screen 14 for the liquid phase main line 3 to pass through. The metal mesh screen 14 is replaceable and 2 to 3 metal mesh screens 14 can be provided. Metal mesh screens 14 with different mesh specifications can be provided and replaced according to foaming needs.

[0047] The rear separation cylinder 5 is provided with a handle 15 for pulling the rear separation cylinder.

[0048] The fixed bracket 9 is used to support the entire switching device and is divided into front and rear support legs. The front support leg is fixedly connected to the front separation cylinder 4 of the outer cylinder 1, and the rear support leg is fixedly connected to the rear end of the inner cylinder 2. The fixed bracket 9 is fixed to the ground or platform.

[0049] During operation, since the outer cylinder is a separate design, the outer cylinder 5 needs to be supported by the inner cylinder 2, so the entire fixed bracket 9 requires a fixed setting and cannot be adjusted; here:

[0050] The front separation cylinder 4 is fixedly connected to the liquid phase main line 3, and the external port of the liquid phase main line 3 is connected to the hose of the fire sprinkler, which needs to be fixed firmly and cannot move;

[0051] The inner tube 2 and the liquid phase rear pipeline 7 are also fixedly connected. The external port of the liquid phase rear pipeline 7 is connected to the hose of the external water pump. The air inlet of the inner tube 2 is connected to the hose of the external gas supply device. They also need to be fixed firmly and immovable to ensure operational stability.

[0052] Therefore, the fixed bracket 9 is preferably set to be fixedly connected to the front separation cylinder 4 of the outer cylinder 1 and the inner cylinder 2, and the rear separation cylinder 5 in the middle section is designed as a movable telescopic adjustment component.

[0053] The switch valve 12 is an electrically controlled valve, and is further provided with a light sensor and a main control board. The light sensor is embedded on the outer surface of the inner tube 2 and is located near the edge of the rear separation cylinder 5 of the outer tube 1. It is connected to the main control board through a line, and the main control board is also connected to the electrically controlled valve; the main control board can be fixedly set in a control box preset on the outside of the outer tube; when the rear separation cylinder 5 is pulled backward, the liquid phase main line 3 and the liquid phase rear line 7 are separated, and the rear separation cylinder 5 blocks the light sensor. The light sensor excites and sends a signal to the main control board, and the main control board controls the electrically controlled valve to close. When the rear separation cylinder is pushed forward, the rear separation cylinder leaves the light sensor, and the main control board controls the electrically controlled valve to open. Such linkage control facilitates firefighters to speed up operations and form a one-step quick switch.

[0054] When the present invention is used, the device is placed near a fire source, the liquid phase rear pipeline is connected to an external fire water source through a hose, and the liquid phase main pipeline is connected to a conventional fire sprinkler through a hose; the rear separation cylinder is pulled to the end, the liquid phase main pipeline and the liquid phase rear pipeline are sealed and connected, the fire sprinkler valve is opened, and the fire water source is directly sprayed out from the liquid phase rear pipeline through the liquid phase main pipeline and the fire sprinkler to perform water-based fire extinguishing;

[0055] When the fire source cannot be extinguished by water and needs to be extinguished by foam, the fire extinguishing agent needs to be switched. At this time, the back end needs to supply a foam mixture. The foam mixture enters the outer cylinder through the liquid phase rear pipeline, and is mixed with the compressed air entering the air inlet in the outer cylinder. Then, it foams through the metal mesh screen. Under the continuous push of the compressed air and the mixture, the foam mixture flows through the foam branch pipe to the liquid phase main pipeline to extinguish the fire with foam.

[0056] Among them, the foam mixture is produced in the following way: during the process of water being transported by the fire pump, the foam proportioning mixer generates negative pressure to suck in the foam fire extinguishing agent and mix to form a foam mixture. After the liquid phase main line and the liquid phase rear line are disconnected, the foam mixture enters the device through the liquid phase rear line, closes the switch valve of the liquid phase main line, and at the same time, injects compressed air into the outer cylinder through the air inlet of the inner cylinder, thereby generating compressed air foam, which is fully foamed after passing through the internal metal mesh screen. Under the continuous push of compressed air and mixed liquid, the foam flows to the liquid phase main line through the foam branch pipe to carry out foam fire extinguishing.

[0057] In addition, there is a pre-installed foam fire extinguishing agent in the outer cylinder of this device. In an emergency situation, such as when using water-based fire extinguishing, firefighters suddenly find that there are special flammable materials at the scene (such as new energy vehicles, car accident scenes, certain fuel oils, chemical materials, power batteries, etc. at the scene) and cannot simply use water-based fire extinguishing. They can close the switch valve on the liquid phase main line, push the rear separation cylinder forward, separate the liquid phase main line and the liquid phase rear line, and water directly enters the outer cylinder and the inner cylinder, and mixes with the foam fire extinguishing agent pre-stored in the outer cylinder; open the external gas supply device, and inject compressed gas into the inner cylinder. The gas blows the foam mixed liquid in the outer cylinder and the inner cylinder to surge, and passes through the internal metal mesh screen for full foaming. Then, under the blowing of the gas and the push of the liquid phase, the foam flows to the front end of the liquid phase main line through the foam branch; open the fire sprinkler valve, and the foam fire extinguishing liquid is sprayed out from the fire sprinkler for temporary emergency foam fire extinguishing, which buys time for subsequent replacement of the foam mixture with a good ratio. It is worth noting that the air inlet can also be used as a liquid inlet for temporary filling of foam fire extinguishing agent concentrate. When the foam concentrate is continuously supplied, the emergency foam supply can also be guaranteed to be uninterrupted.

[0058] In addition, the present invention can also be miniaturized and used to carry out fire extinguishing efficiency experiments of water / foam and other liquid-phase fire extinguishing agents, so as to improve the efficiency and accuracy of experimental research.

[0059] Although the above methods are illustrated and described as a series of structures for simplicity of explanation, it should be understood and appreciated that these methods are not specifically limited because according to one or more embodiments, some structures can occur in different orders and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0060] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fire extinguishing agent switching device, characterized in that: It includes an outer cylinder, an inner cylinder, a liquid phase main line, a foam branch line, a liquid phase rear line and a fixed bracket; The outer cylinder is closed at the front end and open at the rear end, and is divided into a front and rear separate cylinder body. The front and rear separate cylinder bodies are connected by a soft telescopic tube. The distance between the front and rear separate cylinder bodies can be adjusted as the soft telescopic tube is extended and contracted. The outer cylinder contains a foam fire extinguishing agent. The inner cylinder is inserted into the rear end opening of the outer cylinder in a sealed manner, and the rear end of the inner cylinder is exposed from the outer cylinder; the inner cavity of the inner cylinder and the inner cavity of the outer cylinder are connected; the rear separation cylinder can slide back and forth on the outer wall surface of the inner cylinder; The liquid phase main line is inserted into the outer cylinder from the front end of the front separation cylinder and is fixedly connected to the front separation cylinder; the liquid phase rear line is inserted from the rear end of the inner cylinder and is fixedly connected to the inner cylinder; the external port of the liquid phase main line is connected to the fire sprinkler, and the external port of the liquid phase rear line is connected to the external water pump; A soft telescopic tube is provided in the middle section of the liquid phase main line to adjust the length of the liquid phase main line; the internal port of the liquid phase main line and the internal port of the liquid phase rear line are positioned opposite each other, and the internal ports can be connected and separated by the extension and contraction of the liquid phase main line; The rear section of the liquid phase main line at the flexible telescopic tube serves as a movable line and is fixedly connected to the inner side of the rear separation cylinder of the outer cylinder via a bracket. The movement of the rear separation cylinder drives the expansion and contraction of the liquid phase main line, thereby controlling the connection and separation of the liquid phase main line and the liquid phase rear line. When the flexible telescopic tube is in the expanded state, the liquid phase main line and the liquid phase rear line are in a sealed connection state. One end of the foam branch is arranged at the front end of the front separation cylinder of the outer cylinder and communicates with the inner cavity of the outer cylinder; the other end of the foam branch is connected to and passes through the liquid phase main line; The liquid phase main line is provided with an on-off valve; the on-off valve is located after the connection point between the foam branch line and the liquid phase main line; An air inlet is also provided at the rear end of the inner cylinder, and the air inlet is connected to an external gas supply device; The fixed bracket is used to support the entire switching device and is divided into front and rear support legs. The front support leg is fixedly connected to the front separation cylinder of the outer cylinder, and the rear support leg is fixedly connected to the rear end of the inner cylinder; the fixed bracket is fixed to the ground or platform.

2. The fire extinguishing agent switching device according to claim 1, characterized in that: A metal mesh screen for foaming is provided in the outer cylinder and / or the inner cylinder, between the air inlet and the foam branch, and a through hole is provided in the center of the metal mesh screen for the liquid phase main line to pass through.

3. The fire extinguishing agent switching device according to claim 2, characterized in that: The metal mesh screen is a replaceable metal mesh screen, and several metal mesh screens with different mesh specifications are provided according to the foaming needs.

4. The fire extinguishing agent switching device according to claim 1, characterized in that: The internal port of the liquid phase main line is in a bell-mouth shape, and a sealing silica gel is provided on the inner wall of the bell-mouth. After the internal port of the liquid phase rear line is inserted into the internal port of the liquid phase main line, it can fit tightly on the sealing silica gel.

5. The fire extinguishing agent switching device according to claim 1, characterized in that: The switch valve is an electrically controlled valve and is further provided with a linkage control switch. The linkage control switch is connected to the switch valve through a main control board arranged outside the outer cylinder. The linkage control switch can control the switch valve to open and close automatically.

6. The fire extinguishing agent switching device according to claim 1, characterized in that: The rear separation cylinder is provided with a handle for facilitating pulling of the rear separation cylinder.

7. The fire extinguishing agent switching device according to claim 1, characterized in that: There are a plurality of air inlets which are arranged around the surface of the outer cylinder at equal intervals.

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