Ventilation air conditioning duct air tightness detection method and equipment

Abstract

The present application relates to the field of air tightness detection, especially to a ventilation air duct air tightness detection method and equipment, the equipment comprises: a detection platform, both sides of the top of the detection platform are provided with a fixed table, and the fixed table is used for placing the air duct and abutting against one side of the air duct flange, a positioning push plate is arranged on the fixed table to assist the air duct to be centered and increase the flange abutting surface, a sealing plate one and a ventilation pipe are used for sealing and clamping the free end of the air duct flange on one side, and gas is injected into the air duct, a sealing plate two and an air bag are used for sealing and clamping the free end of the air duct flange on the other side, and the air duct is used for storing the gas in the air duct to assist subsequent detection to rapidly increase the pressure; the present application is through the double-side movable sealing structure, the air duct is prevented from being deformed and leaking due to the axial force while being clamped under high pressure, the sealing stability is improved, and the air bag gas recovery pre-pressurization structure is additionally arranged, part of the gas is recovered and used for pre-inflation to improve the detection efficiency.

Description

Technical Field

[0001] This invention relates to the field of airtightness testing, and more particularly to a method and equipment for testing the airtightness of ventilation and air conditioning ducts. Background Technology

[0002] Ventilation and air conditioning ducts are specialized piping components used in ventilation and air conditioning systems for transporting and distributing air. They are typically made of galvanized steel, stainless steel, or composite materials. Their primary functions include supplying, returning, exhausting, and delivering fresh air, as well as regulating airflow. Widely used in building interiors, they are crucial infrastructure components ensuring ventilation, temperature and humidity control, air purification, and fire prevention and smoke extraction. After duct manufacturing, [further details are needed]. The airtightness of the duct is tested using a testing device.

[0003] For example, the air conditioning galvanized duct quality inspection device disclosed in Chinese patent CN218035572U adopts a structure of clamping from both sides to tighten the duct end to achieve end face sealing, and then carry out air tightness testing. However, this clamping and sealing method relies on rigid clamping force to achieve sealing and positioning, which is only suitable for duct products with large wall thickness and high structural strength. For thin-walled galvanized ventilation and air conditioning ducts, due to insufficient plate rigidity and weak self-supporting capacity, problems such as duct wall denting, deformation, and wrinkling are very likely to occur during the rigid clamping and squeezing process. In severe cases, it can cause local cracking and damage to the duct wall, which not only affects the accuracy of the air tightness test results, but also causes irreversible additional damage to qualified ducts, increasing the product scrap rate and production costs.

[0004] To address the aforementioned technical deficiencies, a solution is proposed that aims to provide high-pressure sealing clamping while preventing duct deformation and leakage due to axial force, thereby improving sealing stability and recovering some gas for pre-filling to enhance testing efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method and equipment for testing the air tightness of ventilation and air conditioning ducts, in order to solve the aforementioned technical defects.

[0006] The objective of this invention can be achieved through the following technical solution: a ventilation and air conditioning duct air tightness testing device, comprising: The testing platform has fixed platforms on both sides of its top. The fixed platforms are used for placing the air duct and abutting one side of the air duct flange. The fixed platforms are equipped with positioning push plates that help center the air duct and increase the flange contact surface. The sealing plate and ventilation duct, together with a set of fixed platforms, seal and clamp the free end of the flange on one side of the duct, and inject gas into the duct; The sealing plate and airbag, together with another set of fixed platforms, seal and clamp the free end of the flange on the other side of the air duct, and are used for partial gas storage inside the air duct to assist in rapid pressurization for subsequent testing.

[0007] Preferably, the fixed platform has a U-shaped structure, and positioning push plates are provided on both sides of the fixed platform. Multiple support rods that are slidably connected to the fixed platform are fixedly connected to the positioning push plates. A spring is installed between the end of the support rod and the fixed platform through a connecting plate. A sealing strip is fixedly connected to one side of the positioning push plate and the fixed platform.

[0008] Preferably, the bottom of the fixed platform is provided with a T-shaped groove, and a T-shaped plate is slidably connected in the T-shaped groove. Support plates are fixedly connected to both sides of the bottom of the T-shaped plate. An elastic rope is installed between the support plate and the corresponding positioning push plate. A guide wheel for guiding the corresponding elastic rope is rotatably connected in the T-shaped groove.

[0009] Preferably, the testing platform is slidably connected to the fixed platform via a top-mounted guide rail. The top of the testing platform has a through slot for the T-shaped plate to move through, and the bottom of the testing platform has multiple limiting slots equidistantly spaced along its length and on both sides of the through slot.

[0010] Preferably, bracket one and bracket two are fixedly installed on the opposite sides of the two sets of fixed platforms, respectively. A sealing plate one is installed on bracket one through a cylinder one, and the sealing plate one is slidably connected to bracket one. The ventilation pipe is installed through the sealing plate one, and an air inlet valve and a pressure sensor are provided on the ventilation pipe. A sealing gasket is installed on one side of the sealing plate one.

[0011] Preferably, the second bracket is equipped with a cylinder second for pushing the second sealing plate to move, and the second sealing plate is slidably connected to the second bracket. A sealing gasket is installed on one side of the second sealing plate, and an air hole communicating with the airbag is opened through the second sealing plate, and an air storage valve is threaded into the air hole.

[0012] Preferably, the output end of the cylinder two is fixedly connected to a push plate that is slidably connected to the bracket two, and multiple springs two are fixedly installed between the push plate and the sealing plate two, and the airbag is fixedly connected between the push plate and the sealing plate two.

[0013] One method for testing the air tightness of ventilation and air conditioning ducts includes the following steps: S1: Gravity self-positioning: The duct is placed on the fixed platform and relies on its own weight to press down the T-shaped plate. The elastic rope drives the two sets of positioning push plates to move relative to each other, pushing the duct to move to the middle of the fixed platform. S2: Double-sided non-compression sealing: The cylinders on both sides drive the corresponding sealing plates to move horizontally, and the movable fixed platform and its internal positioning push plate clamp the corresponding flanges on both sides of the air duct. The air duct is fully sealed at both ends under no compression or thrust. S3: Air tightness test judgment: After inflating the air duct to the preset pressure value, the pressure is maintained. The pressure sensor monitors the air pressure in real time. By comparing the air pressure attenuation, it is determined whether the air tightness of the air duct is qualified. S4: Partial Gas Recovery and Energy Storage: After the test is completed, the sealing plate is separated from the air duct in stages, and part of the gas inside the air duct is stored through the airbag; S5: Energy Storage Pre-inflation Reuse: After the next duct is sealed, the airbag releases the stored gas to pre-inflate the duct, quickly establishing the initial air pressure, shortening the inflation time, and improving the overall testing efficiency.

[0014] The beneficial effects of this invention are as follows: This invention utilizes the self-weight of the duct to drive a T-shaped plate linked to an elastic rope, which in turn drives a positioning push plate to clamp the duct. This ensures that ducts of different sizes can communicate with the air vents and ventilation pipes on both sides, eliminating the need for repeated manual alignment and calibration. Furthermore, it employs a dual-sided movable sealing structure, which provides high-pressure sealing and clamping to both flanges of the duct while preventing axial compression and thrust throughout the entire process. This effectively avoids problems such as deformation of thin-walled ducts under pressure and leakage due to misalignment of the sealing surface, significantly improving the stability and sealing performance of the airtight seal and ensuring accurate and reliable basic testing conditions.

[0015] This invention also adds an airbag gas recovery and pre-pressurization mechanism. After a single test, some of the gas inside the duct is recovered and stored in the airbag. During the next test, the stored gas is released to pre-inflate the duct, quickly establishing the initial air pressure, reducing inflation time, and significantly improving the efficiency of batch duct testing. After the test is completed, each mechanism can automatically reset and lock to ensure the alignment consistency of the duct during continuous testing, realizing automated continuous airtightness testing. At the same time, gas recycling reduces fan energy consumption, combining high efficiency and energy saving, and is suitable for the needs of industrial batch duct quality inspection. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings; Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural schematic diagram from another perspective of the present invention; Figure 3 This is a schematic diagram of the structure of the fixing platform of the present invention; Figure 4 This is a schematic diagram of the installation of the sealing plate of the present invention; Figure 5 This is a schematic diagram of the installation of the sealing plate 2 of the present invention; Figure 6 This is a schematic diagram of the placement of the ventilation and air conditioning duct of the present invention.

[0017] Legend: 1. Testing platform; 11. Limiting groove; 2. Fixed platform; 21. Positioning push plate; 22. Spring 1; 23. T-slot; 24. T-plate; 25. Support plate; 26. Elastic rope; 27. Guide wheel; 3. Sealing plate 1; 31. Ventilation duct; 32. Bracket 1; 33. Cylinder 1; 4. Sealing plate II; 41. Airbag; 42. Bracket II; 43. Cylinder II; 44. Push plate; 45. Spring II. Detailed Implementation

[0018] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Please refer to Figures 1-6 As shown, when testing thin-walled galvanized ventilation and air conditioning ducts with a structure that uses a two-sided clamping design, problems such as duct wall dents, deformation, and wrinkles are easily caused due to insufficient rigidity of the sheet metal and weak self-support capacity. In severe cases, this can lead to local cracking and damage to the duct wall, affecting the accuracy of the airtightness test results. It can also cause irreversible additional damage to qualified ducts, increasing the product scrap rate and production costs. The following solutions can be used to address these issues. This embodiment of a ventilation and air conditioning duct air tightness testing device includes: The testing platform 1 has fixed platforms 2 on both sides of its top. The fixed platforms 2 are used to place the air duct and abut against one side of the air duct flange. The fixed platforms 2 are equipped with positioning push plates 21 to help center the air duct and increase the flange contact surface. The testing platform 1 is the overall installation reference. The fixed platforms 2 are used to support the air duct. The positioning push plates 21 can increase the flange contact area, disperse the clamping pressure, avoid local stress concentration deformation of thin-walled air ducts, and achieve the effect of moving and aligning. The sealing plate 3 and the ventilation pipe 31, together with a set of fixed platform 2, seal and clamp the free end of the flange on one side of the duct, and inject gas into the duct. The ventilation pipe 31 realizes the introduction of gas into the duct, ensuring the supply of air pressure for air tightness testing. The sealing plate 4 and the airbag 41, together with another set of fixed platforms 2, seal and clamp the free end of the flange on the other side of the air duct, and are used for storing part of the gas inside the air duct to assist in the rapid pressurization of subsequent tests. The sealing plate 4 achieves the sealing of the flange on the other side, and the airbag 41 recovers part of the gas inside the air duct, realizing the recycling of part of the gas and pre-filling it for the next test, which greatly improves the inflation efficiency.

[0020] The fixed platform 2 has a U-shaped structure, and positioning push plates 21 are provided on both sides of the fixed platform 2. The U-shaped fixed platform 2, together with the two sets of positioning push plates 21, forms a ring-shaped support to adapt to different specifications of air ducts. Multiple support rods that are slidably connected to the fixed platform 2 are fixedly connected on the positioning push plate 21. Springs 22 are installed between the end of the support rod and the fixed platform 2 through the connecting plate. Spring 22 provides a small reset force to the positioning push plate 21. During the removal of the air duct, the positioning push plate 21 is reset and moved under the compression force of spring 22, completing the automatic springback reset of the clamping mechanism. The positioning push plate 21 and one side of the fixed platform 2 are fixedly connected with sealing strips. The sealing strips improve the clamping sealing of the flange side wall and at the same time avoid rigid extrusion that causes deformation and damage to the thin-walled air duct.

[0021] The bottom of the fixed platform 2 is provided with a T-shaped groove 23, and a T-shaped plate 24 is slidably connected in the T-shaped groove 23. Multiple ball bearings are embedded in the top of the T-shaped plate 24 to assist the flexibility of the duct's horizontal movement. Support plates 25 are fixedly connected to both sides of the bottom of the T-shaped plate 24. An elastic rope 26 is installed between the support plate 25 and the corresponding positioning push plate 21. The tensile force of the elastic rope 26 is greater than the compressive force of the spring 22, so that when the T-shaped plate 24 is pressed down, the spring 22 deforms first, and the elastic rope 26 deforms later. A guide wheel 27 is rotatably connected in the T-shaped groove 23 to guide the corresponding elastic rope 26 and to change the direction of force on the elastic rope 26. The flanges on both sides of the duct are located between the sealing plate 3 and the right fixed platform 2, and between the sealing plate 4 and the left fixed platform 2, respectively. The duct is placed on the two fixed platforms 2. The duct contacts the T-shaped plate 24 and pushes the T-shaped plate 24 down by its own weight. The T-shaped plate 24 pulls the positioning push plates 21 on both sides to move relative to each other through the two sets of elastic ropes 26. After the positioning push plates 21 clamp the duct and push the duct to the middle of the fixed platform 2, the T-shaped plate 24 stretches the elastic ropes 26 until the duct pushes the T-shaped plate 24 to the T-groove 23 and abuts against the fixed platform 2.

[0022] The testing platform 1 is slidably connected to the fixed platform 2 via the guide rail installed on the top. The movable connection of the fixed platform 2 ensures that when the fixed platform 2 and the corresponding sealing plate clamp the duct flange, the duct will not be subjected to overall force, thus preventing the duct wall from cracking. The top of the testing platform 1 has a through groove for the T-shaped plate 24 to move. The bottom of the testing platform 1 has multiple limiting grooves 11 equidistantly provided along its length and on both sides of the through groove. The width of the limiting groove 11 is greater than the width of the support plate 25. The support plate 25 on the T-shaped plate 24 enters the limiting groove 11, limiting the translation of the fixed platform 2 within a fixed range. This ensures that when the next air duct is placed, the flange is accurately and quickly positioned between the height platform and the sealing plate. When the air duct is placed, the support plate 25 on the T-shaped plate 24 moves out of the limiting groove 11, without interfering with the movement of the flange held by the fixed platform 2.

[0023] Two sets of fixed platforms 2 are respectively fixedly installed with bracket 1 32 and bracket 2 42 on their opposite sides. A sealing plate 3 is installed on bracket 1 32 through cylinder 1 33, and the sealing plate 3 is slidably connected to bracket 1 32. A ventilation pipe 31 is installed through the sealing plate 3. An air inlet valve and a pressure sensor are set on the ventilation pipe 31. The pressure sensor is located between the sealing plate 3 and the air inlet valve. A sealing gasket is installed on one side of the sealing plate 3. The bracket 1 32 provides a stable installation base. Cylinder 1 33 drives the sealing plate 3 to move and seal. The pressure sensor monitors the air pressure in the pipe in real time to realize automated pressure acquisition and detection judgment. The sealing gasket improves the end face sealing performance.

[0024] A cylinder 2 43 is installed on the bracket 2 42 to push the sealing plate 2 4 to move, and the sealing plate 2 4 is slidably connected to the bracket 2 42. A sealing gasket is installed on one side of the sealing plate 2 4. The cylinder 2 43 drives the sealing plate 2 4 to seal and block. The ventilation pipe 31 is connected to an external fan. The pressure sensor is connected to an external controller, and the controller is connected to a display screen. The fan, together with the ventilation pipe 31, injects gas into the sealed ventilation pipe. The pressure sensor monitors the air pressure data inside the ventilation pipe in real time. The air pressure data is transmitted to the control panel, where the real-time air pressure value is displayed on the screen. The real-time air pressure value is compared with the preset air pressure value until the real-time air pressure value equals the preset air pressure value. Then the fan is stopped and the air inlet valve on the ventilation pipe 31 is closed. The controller sets the airtightness test time. After the airtightness test time is over, the real-time air pressure value is compared with the preset air pressure value for the second time. If the real-time air pressure value is equal to the preset air pressure value, the controller generates a qualified signal and determines that the quality inspection is qualified and the airtightness of the air duct is good. If the real-time air pressure value is less than the preset air pressure value, the controller generates an unqualified signal and determines that the quality inspection is unqualified and the airtightness of the air duct is poor. The sealing plate 4 has a through hole that communicates with the airbag 41, and the air hole is threaded with an air storage valve.

[0025] Example 2: Please refer to Figure 5 and Figure 6 As shown, the problem of low inflation efficiency during multiple duct testing processes can be solved by the following solutions; In this embodiment, a cylinder 43 is installed on the bracket 42 to move the sealing plate 4. The sealing plate 4 is slidably connected to the bracket 42. A sealing gasket is installed on one side of the sealing plate 4. An air hole communicating with the airbag 41 is opened through the sealing plate 4. An air storage valve is threaded into the air hole. The air storage valve controls the opening and closing of the airbag 41 and the inner cavity of the air duct, realizing the sealed storage of part of the gas, providing an air source for the subsequent pre-filling of the air duct, greatly shortening the blower filling time and improving the efficiency of batch testing.

[0026] The output end of cylinder 2 43 is fixedly connected to a push plate 44 that is slidably connected to bracket 2 42, and multiple springs 2 45 are fixedly installed between the push plate 44 and the sealing plate 2 4. The airbag 41 is fixedly connected between the push plate 44 and the sealing plate 2 4. The springs 2 45 realize flexible buffer transmission, so that the sealing plate 2 4 remains in a clamping and sealing state during the initial reset process of cylinder 2 43, providing sufficient time for the airbag 41 to inflate. At the same time, the airbag 41 stretches and compresses with the displacement of the push plate 44, automatically completing the storage and deflation of air. Cylinder 2 43 carries push plate 44 to reset and move. During the movement, the compression force of spring 2 45 causes sealing plate 2 4 to still cooperate with left fixed platform 2 to clamp the corresponding flange. At the same time, the airbag 41 is stretched and expanded. Combined with the large air pressure inside the air duct, some air is forced to enter the airbag 41 through the air hole and air storage valve for storage until the airbag 41 is fully expanded and reaches the maximum air storage capacity. When the air storage valve is closed, the push plate 44, carrying the sealing plate 2 4, separates from the air duct. Subsequently, the cylinder 33 pushes the sealing plate 3 to separate from the air duct, and the air duct after testing is removed. For the next air duct air tightness test, the sealing plate 3 and the sealing plate 2 4 seal both ends of the air duct. During the continuous movement of the push plate 44, the air storage valve is opened and remains open, squeezing the stored air in the airbag 41 into the air duct, causing the air duct to form an initial air pressure value, prompting the fan to quickly complete the air injection process of the preset air pressure value, and improving the air tightness test efficiency.

[0027] Example 3: Please refer to Figures 1-6 As shown, the present invention also proposes a method for testing the airtightness of ventilation and air conditioning ducts, comprising the following steps: Step 1: Gravity self-positioning: The duct is placed on the fixed platform 2 and presses down on the T-shaped plate 24 by its own weight. The elastic rope 26 drives the corresponding two sets of positioning push plates 21 to move relative to each other, pushing the duct to the middle of the fixed platform 2. The duct is placed on the two sets of fixed platforms 2. The duct contacts the T-shaped plate 24 and pushes the T-shaped plate 24 down by its own weight. At the same time, the support plate 25 on the T-shaped plate 24 moves out of the limiting groove 11. The T-shaped plate 24 pulls the positioning push plates 21 on both sides to move relative to each other through the two sets of elastic ropes 26. After the positioning push plates 21 clamp the duct and push the duct to the middle of the fixed platform 2, the T-shaped plate 24 stretches the elastic rope 26 until the duct pushes the T-shaped plate 24 to the T-shaped groove 23 and abuts against the fixed platform 2. The flanges on both sides of the duct are located between the sealing plate 1 3 and the right fixed platform 2, and between the sealing plate 2 4 and the left fixed platform 2, respectively. Step Two: Double-sided non-compression sealing: The cylinders on both sides drive the corresponding sealing plates to move horizontally, cooperating with the movable fixed platform 2 and its internal positioning push plate 21 to clamp the corresponding flanges on both sides of the air duct. Under the condition that the air duct is not subjected to compression or thrust, the two ends of the air duct are fully sealed. Cylinder 1 33 pushes the sealing plate 1 3 to move horizontally. Combined with the sliding installation of the right fixed platform 2 and the two sets of positioning push plates 21 inside the right fixed platform 2, the right flange of the air duct is clamped on both sides, so that the sealing plate 1 3 seals the right end face of the air duct. Cylinder 2 43 pushes the auxiliary plate to move. The auxiliary plate drives the sealing plate 2 4 to move horizontally synchronously through the spring 2 45. Combined with the sliding installation of the left fixed platform 2 and the two sets of positioning push plates 21 inside the left fixed platform 2, the left flange of the air duct is clamped on both sides, so that the sealing plate 1 3 seals the left end face of the air duct. Thus, under the condition that the air duct is not subjected to compression or thrust, the two ends of the air duct are fully sealed. Step 3: Air tightness test and judgment: After inflating the duct to the preset pressure value, the pressure is maintained. The pressure sensor monitors the air pressure in real time. By comparing the air pressure attenuation, the air tightness of the duct is determined. The ventilation pipe is connected to an external fan, and the pressure sensor is connected to an external controller, which is connected to a display screen. The fan, together with the ventilation pipe 31, injects gas into the sealed duct. The pressure sensor monitors the air pressure data inside the duct in real time. The air pressure data is transmitted to the control panel and the real-time air pressure value is displayed on the screen. The real-time air pressure value is compared with the preset air pressure value until the real-time air pressure value equals the preset air pressure value. Then the fan is stopped and the air inlet valve on the ventilation pipe 31 is closed. The controller sets the airtightness test time. After the airtightness test time is over, the real-time air pressure value is compared with the preset air pressure value a second time. If the real-time air pressure value is equal to the preset air pressure value, the controller generates a qualified signal and determines that the quality inspection is qualified and the airtightness of the duct is good. If the real-time air pressure value is less than the preset air pressure value, the controller generates an unqualified signal and determines that the quality inspection is unqualified and the airtightness of the duct is poor. Step 4: Partial Gas Recovery and Energy Storage: After the test is completed, the sealing plate is detached from the air duct in stages, and part of the gas inside the air duct is stored through the airbag 41. After the air tightness test is completed, the cylinder 43 carries the push plate 44 to reset and move horizontally. During the horizontal movement, the compression force of the spring 45 causes the sealing plate 4 to still cooperate with the left fixed platform 2 to clamp the corresponding flange. At the same time, the airbag 41 is stretched and expanded. Combined with the large air pressure inside the air duct, part of the air enters the airbag 41 through the air hole and the air storage valve for storage until the airbag 41 is fully expanded and reaches the maximum gas storage capacity. When the gas storage valve is closed, the push plate 44 separates the sealing plate 2 4 from the air duct. Then, the cylinder 33 pushes the sealing plate 3 to separate from the air duct, and the air duct after inspection is taken out. During the removal process, the positioning push plate 21 is reset and moved under the compression force of the spring 22, and the T-shaped plate 24 is raised in conjunction with the elastic rope 26. The support plate 25 on the T-shaped plate 24 enters the limiting groove 11, which limits the translation of the fixed platform 2 to a fixed range, so that when the next air duct is placed, the flange is accurately and quickly positioned between the height platform and the sealing plate. Step 5: Pre-inflation and reuse of stored gas: After the next duct is sealed, the airbag 41 releases the stored gas to pre-inflate the duct, quickly establishing the initial air pressure, shortening the inflation time, and improving the overall testing efficiency. For the next duct air tightness test, sealing plate 3 and sealing plate 4 seal both ends of the duct. During the continuous movement of the pushing plate 44, the air storage valve opens and remains open, squeezing the stored air in the airbag 41 into the duct, causing the duct to form an initial air pressure value. This prompts the fan to quickly complete the air injection process of the preset air pressure value, improving the air tightness test efficiency.

[0028] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for testing the air tightness of ventilation and air conditioning ducts, characterized in that, include: The testing platform (1) has fixed platforms (2) on both sides of its top. The fixed platforms (2) are used for placing the air duct and abutting one side of the air duct flange. The fixed platforms (2) are equipped with positioning push plates (21) to help center the air duct and increase the flange contact surface. The sealing plate (3) and ventilation pipe (31) are used together with a set of fixed platform (2) to seal and clamp the free end of the flange on one side of the duct and inject gas into the duct. The sealing plate 2 (4) and the airbag (41), together with another set of fixed platform (2), seal and clamp the free end of the flange on the other side of the air duct, and are used for partial gas storage in the air duct to assist in rapid pressurization for subsequent testing; The bottom of the fixed platform (2) is provided with a T-shaped groove (23), and a T-shaped plate (24) is slidably connected in the T-shaped groove (23). Multiple ball bearings are embedded in the top of the T-shaped plate (24) to assist the flexibility of the duct movement. Support plates (25) are fixedly connected to both sides of the bottom of the T-shaped plate (24). An elastic rope (26) is installed between the support plate (25) and the corresponding positioning push plate (21). The tensile force of the elastic rope (26) is greater than the compressive force of the spring (22), so that when the T-shaped plate (24) is pressed down, the spring (22) deforms first, and the elastic rope (26) deforms later. The duct is placed on two sets of fixed platforms (2). The duct contacts the T-shaped plate (24) and pushes the T-shaped plate (24) down by its own weight. The T-shaped plate (24) pulls the positioning push plates (21) on both sides to move relative to each other through two sets of elastic ropes (26). After the positioning push plates (21) clamp the duct and push the duct to move to the middle of the fixed platform (2), the T-shaped plate (24) stretches the elastic ropes (26) until the duct pushes the T-shaped plate (24) to the T-shaped groove (23) and abuts against the fixed platform (2). Two sets of fixed platforms (2) are respectively fixedly installed on opposite sides of bracket 1 (32) and bracket 2 (42). Cylinder 2 (43) is installed on bracket 2 (42) to push sealing plate 2 (4) to move. Sealing plate 2 (4) is slidably connected to bracket 2 (42). Sealing gasket is installed on one side of sealing plate 2 (4). Air hole communicating with airbag (41) is opened through sealing plate 2 (4). Air storage valve is threaded in the air hole. Push plate (44) is fixedly connected to the output end of cylinder 2 (43) and slidably connected to bracket 2 (42). Multiple springs 2 (45) are fixedly installed between push plate (44) and sealing plate 2 (4). Airbag (41) is fixedly connected between push plate (44) and sealing plate 2 (4).

2. The ventilation and air conditioning duct air tightness testing equipment according to claim 1, characterized in that, The fixed platform (2) has a U-shaped structure, and both sides of the fixed platform (2) are provided with positioning push plates (21). Multiple support rods that are slidably connected to the fixed platform (2) are fixedly connected to the positioning push plate (21). A spring (22) is installed between the end of the support rod and the fixed platform (2) through a connecting plate. A sealing strip is fixedly connected to one side of the positioning push plate (21) and the fixed platform (2).

3. The ventilation and air conditioning duct air tightness testing equipment according to claim 2, characterized in that, The T-groove (23) is rotatably connected to a guide wheel (27) for guiding the corresponding elastic rope (26).

4. The ventilation and air conditioning duct air tightness testing equipment according to claim 1, characterized in that, The detection platform (1) is slidably connected to the fixed platform (2) via a guide rail installed on the top. A through slot is provided on the top of the detection platform (1) for the T-shaped plate (24) to move. Multiple limiting slots (11) are provided at equal intervals on both sides of the through slot along the length of the bottom of the detection platform (1).

5. The ventilation and air conditioning duct air tightness testing equipment according to claim 1, characterized in that, The two sets of fixed platforms (2) are respectively fixedly installed with bracket one (32) and bracket two (42) on their opposite sides. A sealing plate one (3) is installed on the bracket one (32) through a cylinder one (33), and the sealing plate one (3) is slidably connected to the bracket one (32). The ventilation pipe (31) is installed through the sealing plate one (3). An air inlet valve and a pressure sensor are provided on the ventilation pipe (31). A sealing gasket is installed on one side of the sealing plate one (3).

6. A method for testing the air tightness of ventilation and air conditioning ducts, using the air tightness testing equipment for ventilation and air conditioning ducts as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Gravity self-positioning: The duct is placed on the fixed platform (2) and presses down on the T-shaped plate (24) by its own weight. The elastic rope (26) drives the two corresponding positioning push plates (21) to move relative to each other, pushing the duct to move to the middle of the fixed platform (2); S2: Double-sided non-extrusion sealing: The cylinders on both sides drive the corresponding sealing plates to move horizontally, and the fixed platform (2) and its internal positioning push plate (21) clamp the corresponding flanges on both sides of the air duct. The air duct is fully sealed at both ends under the condition that it is not subjected to extrusion or thrust. S3: Air tightness test judgment: After inflating the air duct to the preset pressure value, the pressure is maintained. The pressure sensor monitors the air pressure in real time. By comparing the air pressure attenuation, it is determined whether the air tightness of the air duct is qualified. S4: Partial gas recovery and energy storage: After the test is completed, the sealing plate is separated from the air duct in stages, and part of the gas inside the air duct is stored through the air bag (41); S5: Energy storage pre-filling gas reuse: After the next air duct is sealed, the air bag (41) releases the stored gas to pre-fill the air duct, quickly establishes the initial air pressure, shortens the filling time, and improves the overall detection efficiency.

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