Equivalent air permeability measurement device

Abstract

This invention belongs to the field of equivalent air permeability measurement technology and discloses a measuring device for equivalent air permeability, including a sealed shell, fixed bases, and elastic pads. Two fixed bases are provided, located on two opposite inner sidewalls of the sealed shell. Each fixed base has mounting holes, which are coaxially arranged. The elastic pads are placed within the mounting holes and have mounting grooves. The two ends of the sample to be tested are respectively inserted into the mounting grooves of the two elastic pads, and the elastic pads are pressed tightly against the mounting holes. The sample to be tested divides the accommodating cavity of the sealed shell into a first cavity and a second cavity. This invention utilizes the elastic sealing performance of the elastic pads, allowing high-pressure gas in either the first or second cavity to permeate only through the sample to be tested. This solves the problem of gas sealing on both sides of the sample when measuring equivalent air permeability using the differential pressure method, thereby improving the measurement accuracy of the material's equivalent air permeability.

Description

Technical Field

[0001] This utility model relates to the field of equivalent air permeability measurement technology, and in particular to a device for measuring equivalent air permeability. Background Technology

[0002] Air permeability refers to the ease with which gas can pass through a solid bulk material layer or material, and is a key indicator for measuring the porosity and air permeability of a material. It is widely used in various industries, such as medical, pharmaceutical, chemical, textile, construction, and packaging, and has a significant impact on product quality and performance. With the development of science and technology, air permeability measurement technology is also constantly improving. Modern air permeability testing instruments, such as sponge-air permeability testers and differential pressure gas permeability testers, employ advanced measurement principles and technologies to more accurately measure the air permeability of materials. These instruments are typically based on the diffusion characteristics of gas molecules within a material, determining air permeability by measuring the permeation rate under different pressures on both sides of the material. They offer advantages such as high measurement accuracy, ease of operation, and wide applicability, providing strong support for air permeability research.

[0003] Currently, air permeability testing methods are divided into two categories: differential pressure method and isobaric method. There are certain standards to follow, but there may be differences between different experimental devices, such as the way the test sample is fixed. In actual operation, it may also be affected by various factors (such as external wind speed), resulting in unstable airflow and thus affecting the accuracy of the measurement results. Utility Model Content

[0004] The purpose of this invention is to provide a device for measuring equivalent air permeability, which uses the differential pressure method to measure the equivalent air permeability and solves the problem of gas sealing on both sides of the sample being tested.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A device for measuring equivalent air permeability, comprising:

[0007] A sealed housing, inside which the sample to be tested is placed;

[0008] The fixing base is provided in two places, which are located on two opposite inner sidewalls of the sealing housing. The fixing base is provided with mounting holes, and the mounting holes of the two fixing bases are coaxially arranged.

[0009] An elastic pad is disposed in the mounting hole and has a mounting groove. The two ends of the sample to be tested are respectively inserted into the mounting grooves of the two elastic pads and the elastic pads are pressed against the mounting hole. The sample to be tested divides the receiving cavity of the sealing shell into a first cavity and a second cavity.

[0010] In some embodiments, the mounting hole is a through hole, and the elastic pad, when disposed in the mounting hole, can abut against the inner wall of the sealing housing.

[0011] In some embodiments, the sealing housing includes a first housing and a second housing, the second housing and the second housing being detachably and sealingly connected, and the two fixing seats are respectively disposed on the bottom wall of the first housing and the bottom wall of the second housing.

[0012] In some embodiments, an adjustment shim is provided between the first shell and the second shell.

[0013] In some embodiments, the sealing housing includes a third housing and a fourth housing, and the fixing seat is disposed within the third housing or the fourth housing.

[0014] In some embodiments, the mounting base is detachably connected to the inner wall of the sealing housing.

[0015] In some embodiments, the fixing seat is a flange seat, and the flange seat is fixed to the sealing housing by bolts.

[0016] In some embodiments, the device for measuring equivalent air permeability further includes:

[0017] A vacuum pump, wherein the vacuum pump connects the first cavity and the second cavity through a vacuum tube to evacuate the first cavity and the second cavity;

[0018] A pressure pump, wherein the pressure pump is connected to the first chamber or the second chamber via an air pipe to provide high-pressure gas, and the air pipe is provided with a first electric valve;

[0019] A first pressure gauge is disposed in the first cavity to measure the gas pressure in the first cavity;

[0020] A second pressure gauge is installed in the second chamber to measure the gas pressure in the second chamber.

[0021] In some embodiments, the vacuum tube includes a first tube, a second tube, and a third tube that are connected in a continuous manner. The first ends of the first tube and the second tube are respectively connected to a first cavity and a second cavity. The second ends of the first tube and the second tube are each connected to one end of the third tube. The other end of the third tube is connected to the vacuum pump. The first tube and the second tube are respectively provided with a second electric valve.

[0022] In some embodiments, the device for measuring equivalent air permeability further includes a control unit, wherein the first pressure gauge, the second pressure gauge, the first electric valve, the second electric valve, the vacuum pump, and the pressurizing pump are respectively communicatively connected to the control unit.

[0023] The beneficial effects of this utility model are:

[0024] The equivalent air permeability measuring device provided by this utility model uses a fixed seat and an elastic pad inside a sealed housing to install and fix the sample to be tested. This allows the sample to divide the cavity of the sealed housing into a first cavity and a second cavity, facilitating the measurement of the equivalent air permeability using the differential pressure method. By utilizing the elastic sealing performance of the elastic pad, the high-pressure gas in the first or second cavity can only pass through the sample to be tested, solving the problem of gas sealing on both sides of the sample and thus improving the measurement accuracy of the material's equivalent air permeability. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the equivalent air permeability measuring device provided in this embodiment of the utility model.

[0026] In the picture:

[0027] 100. The sample being tested;

[0028] 1. Sealed housing; 11. First chamber; 12. Second chamber; 2. Fixing base; 3. Elastic pad; 4. Vacuum pump; 41. Vacuum tube; 411. First tube; 412. Second tube; 413. Third tube; 42. Second electric valve; 5. Pressurization pump; 51. Air tube; 52. First electric valve; 6. First pressure gauge; 7. Second pressure gauge; 8. Control unit. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0030] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0033] This utility model embodiment provides a device for measuring equivalent air permeability, such as... Figure 1 As shown, this device can be used to measure the equivalent air permeability of a sample 100. The measurement accuracy of the equivalent air permeability is improved by enhancing the sealing performance of the sample 100. Specifically, this embodiment of the invention provides a measuring device for equivalent air permeability, comprising a sealing housing 1, a fixing seat 2, and an elastic pad 3. The sample 100 is disposed within the sealing housing 1. Two fixing seats 2 are provided, located on two opposite inner sidewalls of the sealing housing 1. Each fixing seat 2 has a mounting hole, and the mounting holes of the two fixing seats 2 are coaxially arranged. The elastic pad 3 is disposed within the mounting hole and has a mounting groove. Both ends of the sample 100 are respectively inserted into the mounting grooves of the two elastic pads 3, and the elastic pads 3 are pressed against the mounting hole. The sample 100 divides the accommodating cavity of the sealing housing 1 into a first cavity 11 and a second cavity 12.

[0034] The equivalent air permeability measuring device provided by this utility model uses a fixing seat 2 and an elastic pad 3 inside a sealed housing 1 to install and fix the test sample 100. This allows the test sample 100 to divide the receiving cavity of the sealed housing 1 into a first cavity 11 and a second cavity 12, so as to facilitate the measurement of the equivalent air permeability using the pressure difference method. By utilizing the elastic sealing performance of the elastic pad 3, the high-pressure gas in the first cavity 11 or the second cavity 12 can only pass through the test sample 100, thus solving the gas sealing problem on both sides of the test sample 100 and improving the measurement accuracy of the material's equivalent air permeability.

[0035] In some embodiments, the mounting hole is a through hole, and the elastic pad 3 can abut against the inner wall of the sealing housing 1 when it is disposed in the mounting hole.

[0036] like Figure 1 As shown, a mounting hole is provided at the center of the fixing base 2. When the fixing base 2 is fixedly connected, it is ensured that the two mounting holes are coaxial. The outer diameter of the elastic pad 3 is slightly larger than the diameter of the mounting hole, so that when the elastic pad 3 is installed in the mounting hole, the outer wall of the elastic pad 3 is in close contact with the inner wall of the mounting hole, improving the sealing performance. At the same time, the mounting hole is a through hole, so that the outer wall of the end of the elastic pad 3 facing away from the test sample 100 can be in close contact with the inner wall of the sealing shell 1, improving the sealing performance. Among them, the sealing shell 1 and the fixing base 2 are generally made of rigid materials, such as metal, which have good sealing performance. After the sealing shell 1 and the fixing base 2 are fixedly connected, the sealing performance between the rigid materials is poor. In order to solve this problem, this embodiment of the utility model provides an elastic pad 3, which can seal the contact surface between the sealing shell 1 and the fixing base 2, improving the sealing performance. The elastic pad 3 can be made of high-density, high-elasticity rubber.

[0037] To facilitate the installation of the sample 100 under test, this utility model provides two types of sealing housings 1, which are split structures. The first type of sealing housing 1 includes a first housing and a second housing, which are detachably and sealed together. Two fixing seats 2 are respectively provided on the bottom wall of the first housing and the bottom wall of the second housing.

[0038] The connection and sealing between the first and second shells is existing technology and will not be elaborated or limited in this embodiment. Two fixing seats 2 are respectively installed in the first and second shells. When installing the first and second shells, one end of the sample 100 to be tested is first installed in the fixing seat 2 and the elastic pad 3. Then, when closing the cover, the other end of the sample 100 is aligned with the other fixing seat 2 and the elastic pad 3 and inserted, further pressing the first and second shells together to fix them. This facilitates further improvement of the sealing performance at both ends of the sample 100 through the pre-tightening force between the first and second shells. It should be noted that the dimensions need to be designed in advance to avoid damaging the sample 100.

[0039] In some embodiments, an adjustment shim is provided between the first shell and the second shell.

[0040] When two mounting bases 2 are respectively installed on the first and second shells, the first and second shells can press the two mounting bases 2 together during installation of the sample 100. During the pressing connection between the first and second shells, the elastic pads 3 at both ends of the sample 100 are compressed and deformed, pressing the elastic pads 3 into the mounting holes of the mounting bases 2, thus improving the sealing performance. By setting an adjusting shim, the sealing connection performance between the first and second shells can be increased. At the same time, by setting the overall thickness of the adjusting shim, the size of the sealing shell 1 can be adjusted, thereby improving the adaptability of the sealing shell 1 to test samples 100 of various sizes, resulting in good versatility and reducing measurement costs.

[0041] The second type of sealed housing 1 includes a third housing and a fourth housing, with the fixing seat 2 disposed within the third housing or the fourth housing. Figure 1 In the structure shown, the third shell is the bottom shell, the fourth shell is the top cover, and the fixing seat 2 is set inside the third shell. When the third shell and the fourth shell are connected, the sample 100 under test divides the receiving cavity of the sealed housing 1 into a first cavity 11 and a second cavity 12 of equal capacity. By setting the fixing seat 2 inside the third shell, during installation, elastic pads 3 are first installed at both ends of the sample 100 under test, and then the fixing seat 2 is sleeved on the sample 100 under test. After the sample 100 under test slides down from top to bottom and is installed in the set position inside the third shell, the fixing seat 2 is fixed to the side wall of the third shell; then the third shell and the fourth shell are connected and fixed to complete the sealing installation.

[0042] In some embodiments, the mounting base 2 is detachably connected to the inner sidewall of the sealing housing 1. The connection method is such as bolt connection, in which case the thickness of the sealing housing 1 needs to ensure that no gas leakage occurs on the sidewall after the bolt connection.

[0043] In some embodiments, the fixing seat 2 is a flange seat, and the flange seat is fixed to the sealing housing 1 by bolts. The flange seat can be a pre-fabricated structure, with pre-drilled connection holes at designated locations on the sealing housing 1 for easy positioning and installation, improving installation efficiency. The flange seat generally has through mounting holes, which can reduce processing costs.

[0044] In some embodiments, the device for measuring equivalent air permeability further includes a vacuum pump 4, a pressurizing pump 5, a first pressure gauge 6, and a second pressure gauge 7. The vacuum pump 4 is connected to the first chamber 11 and the second chamber 12 through a vacuum tube 41 to evacuate the first chamber 11 and the second chamber 12. The pressurizing pump 5 is connected to the first chamber 11 or the second chamber 12 through an air tube 51 to provide high-pressure gas. A first electric valve 52 is provided on the air tube 51. The first pressure gauge 6 is provided in the first chamber 11 to measure the gas pressure in the first chamber 11. The second pressure gauge 7 is provided in the second chamber 12 to measure the gas pressure in the second chamber 12.

[0045] like Figure 1As shown, the vacuum tube 41 includes a first tube 411, a second tube 412, and a third tube 413 connected in series. The first ends of the first tube 411 and the second tube 412 are respectively connected to the first cavity 11 and the second cavity 12. The second ends of the first tube 411 and the second tube 412 are both connected to one end of the third tube 413. The other end of the third tube 413 is connected to the vacuum pump 4. The first tube 411 and the second tube 412 are respectively equipped with second electric valves 42. The first tube 411 and the second tube 412 are connected to the first cavity 11 and the second cavity 12, respectively. The first tube 411 and the second tube 412 are connected to the third tube 413 via a T-junction to access the vacuum pump 4. This allows one vacuum pump 4 to simultaneously evacuate the first cavity 11 and the second cavity 12, improving vacuum efficiency and ensuring that the first cavity 11 and the second cavity 12 have the same initial vacuum level. The first tube 411, the second tube 412, and the third tube 413 can be a three-way pipe with an integrated structure, providing good sealing performance. The two second electric valves 42 installed on the first pipe 411 and the second pipe 412 are synchronous control valves to achieve synchronous vacuuming of the first chamber 11 and the second chamber 12. The first electric valve 52 installed on the air pipe 51 is used to control the opening and closing of the air pipe 51. When the pressurizing pump 5 is started, the air flow or pressure can be controlled more precisely through the first electric valve 52.

[0046] In some embodiments, the device for measuring equivalent air permeability further includes a control unit 8. The first pressure gauge 6, the second pressure gauge 7, the first electric valve 52, the second electric valve 42, the vacuum pump 4, and the pressurization pump 5 are all communicatively connected to the control unit 8. The control unit 8 is used to achieve fully automatic measurement control. Both the first electric valve 52 and the second electric valve 42 are solenoid valves to improve measurement accuracy and efficiency. While acquiring the actual pressure of the first pressure gauge 6 and the second pressure gauge 7 in real time, the control unit 8 performs curve analysis and data calculation on the actual pressure to monitor the measurement process.

[0047] The equivalent air permeability measuring device provided by this utility model is used to realize the pressure difference method test based on vacuum. Specifically, the receiving cavity of the sealed housing 1 is divided into two independent spaces by the test sample 100. First, the second electric valve 42 is opened to evacuate both the first cavity 11 and the second cavity 12 to a vacuum using the vacuum pump 4, and then the second electric valve 42 is closed. Then, the first electric valve 52 is opened to quickly fill one side (the first cavity 11, the high-pressure side) with air at a fixed pressure difference (absolute pressure value), while the other side (the second cavity 12, the low-pressure side) is kept in a vacuum state. In this way, a gas pressure difference with a fixed pressure difference is formed on both sides of the test sample 100, and the first electric valve 52 is closed. Air permeates from the high-pressure side to the low-pressure side through the test sample 100, causing a pressure change on the low-pressure side. By measuring the pressure change of the first cavity 11 and the second cavity 12 using the first pressure gauge 6 and the second pressure gauge 7 respectively, the equivalent air permeability of the test sample 100, that is, the gas permeability (GTR) per unit time, can be calculated.

[0048]

[0049] In the formula:

[0050] V C —Low-pressure side volume;

[0051] T—Test temperature (thermodynamic temperature);

[0052] P U —Gas pressure on the high-pressure side;

[0053] A—Effective penetration area;

[0054] dp / dt — The change in pressure on the low-pressure side per unit time after the permeation state has stabilized;

[0055] R—gas constant.

[0056] The unit of GTR is

[0057] This invention utilizes the vacuum method within the differential pressure method to obtain the equivalent air permeability of the tested sample 100. It records the process from a fixed differential pressure to a vacuum until the air pressure on both sides of the tested sample 100 reaches equilibrium, and then calculates the air permeability data. This method is simple and easy to implement, and it satisfies the requirement that the tested sample 100 is a solid material of a specific shape, fulfilling basic measurement requirements and solving the problem of difficulty in measuring the air permeability of specially shaped solid materials.

[0058] Before testing, the sample 100 is cleaned. First, use a lint-free cloth dampened with an appropriate amount of anhydrous ethanol or acetone, or other organic solvent, to gently wipe the surface of the sample 100 to remove contaminants such as grease and dust. Next, use an ultrasonic cleaner to perform a further deep cleaning of the sample 100, ensuring that even the tiny pores on the surface are effectively cleaned. After cleaning, place the sample 100 in a dust-free environment to air dry naturally or use a drying oven to accelerate drying, avoiding residual moisture that could affect the test results.

[0059] To ensure the accuracy and comparability of test results, the testing environment must be strictly controlled. The testing room should maintain a constant temperature and humidity. Specific environmental conditions include, but are not limited to, temperature, humidity, and any external factors that may affect the test results.

[0060] During testing, the method of fixing the sample 100 directly affects the accuracy of the test results. It is essential to ensure that the sample 100 does not shift or deform during the test, and that the sample completely covers the test area. The integrity and airtightness of components such as the vacuum pump 4, pressurization pump 5, first pressure gauge 6, and second pressure gauge 7 are calibrated and verified. The sealing housing 1 is then sealed and fixed, and the sample 100 is clamped with uniform pressure to ensure a complete seal.

[0061] Close the first electric valve 52, open both second electric valves 42, and start the vacuum pump 4 to evacuate the first chamber 11 and the second chamber 12 of the air permeability test chamber. During the vacuuming process, it is necessary to observe the working status of the vacuum pump and the pressure changes inside the air permeability test chamber, that is, to collect and record the data collected by the first pressure gauge 6 and the second pressure gauge 7 in real time to ensure that the vacuuming effect is good. Continue vacuuming for a period of time to ensure that the low air permeability test sample 100 can completely expel all absorbed gas.

[0062] Close the second electric valve 42 to maintain a vacuum state in the first chamber 11 and the second chamber 12. Open the first electric valve 52 and start the pressurization pump 5 to quickly add air at a fixed pressure (generally 0.1 MPa) to the first chamber 11 or the second chamber 12, then quickly close it. Simultaneously, start recording the values ​​of the first pressure gauge 6 and the second pressure gauge 7. Air permeates from the fixed pressure side through the test sample 100 into the vacuum side, and the changing trend of the gas permeation curve is observed until a stable rate is reached. At this point, record three data points after stable permeation to reduce random errors, take the arithmetic mean, and calculate the equivalent air permeability value of the test sample 100. If necessary, the accuracy of the results can be improved by increasing the number of tests or increasing the measurement precision.

[0063] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A device for measuring equivalent air permeability, characterized in that, include: A sealed housing (1) is provided, and the sample to be tested (100) is placed inside the sealed housing (1); Fixed seat (2), two fixed seats (2) are provided, the two fixed seats (2) are provided on two opposite inner side walls of the sealing housing (1), the fixed seat (2) is provided with mounting holes, and the mounting holes of the two fixed seats (2) are coaxially arranged; An elastic pad (3) is provided in the mounting hole. The elastic pad (3) has a mounting groove. The two ends of the test sample (100) are respectively inserted into the mounting grooves of the two elastic pads (3) and the elastic pads (3) are pressed against the mounting hole. The test sample (100) divides the receiving cavity of the sealing housing (1) into a first cavity (11) and a second cavity (12).

2. The measuring device for equivalent air permeability according to claim 1, characterized in that, The mounting hole is a through hole, and when the elastic pad (3) is placed in the mounting hole, it can abut against the inner wall of the sealing housing (1).

3. The measuring device for equivalent air permeability according to claim 1, characterized in that, The sealed housing (1) includes a first housing and a second housing, which are detachably and sealed together. The two fixing seats (2) are respectively disposed on the bottom wall of the first housing and the bottom wall of the second housing.

4. The device for measuring equivalent air permeability according to claim 3, characterized in that, An adjusting shim is provided between the first shell and the second shell.

5. The measuring device for equivalent air permeability according to claim 1, characterized in that, The sealed housing (1) includes a third housing and a fourth housing, and the fixing seat (2) is disposed inside the third housing or the fourth housing.

6. The measuring device for equivalent air permeability according to claim 1, characterized in that, The fixing seat (2) is detachably connected to the inner wall of the sealing housing (1).

7. The device for measuring equivalent air permeability according to claim 6, characterized in that, The fixed seat (2) is a flange seat, and the flange seat is fixed to the sealing housing (1) by bolts.

8. The device for measuring equivalent air permeability according to claim 1, characterized in that, Also includes: A vacuum pump (4) is used to evacuate the first chamber (11) and the second chamber (12) through a vacuum tube (41). A pressure pump (5) is connected to the first chamber (11) or the second chamber (12) via an air pipe (51) to provide high-pressure gas. The air pipe (51) is provided with a first electric valve (52). A first pressure gauge (6) is provided in the first cavity (11) to measure the gas pressure in the first cavity (11); A second pressure gauge (7) is provided in the second chamber (12) to measure the gas pressure in the second chamber (12).

9. The measuring device for equivalent air permeability according to claim 8, characterized in that, The vacuum tube (41) includes a first tube (411), a second tube (412), and a third tube (413) connected in series. The first ends of the first tube (411) and the second tube (412) are respectively connected to the first cavity (11) and the second cavity (12). The second ends of the first tube (411) and the second tube (412) are each connected to one end of the third tube (413). The other end of the third tube (413) is connected to the vacuum pump (4). The first tube (411) and the second tube (412) are respectively provided with a second electric valve (42).

10. The measuring device for equivalent air permeability according to claim 9, characterized in that, It also includes a control unit (8), and the first pressure gauge (6), the second pressure gauge (7), the first electric valve (52), the second electric valve (42), the vacuum pump (4) and the pressurizing pump (5) are respectively connected to the control unit (8).

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