A wide-range air leakage amount detection device including a minute flow measurement

Abstract

The application discloses a wide-range air leakage amount detection device containing micro-flow measurement and relates to the technical field of air leakage amount detection.The wide-range air leakage amount detection device comprises an air flow measurement device and an automatic stable pressure ventilator, the air outlet of the air flow measurement device is connected with the air inlet of the automatic stable pressure ventilator, the air flow measurement device comprises a measurement pipeline, the inside of the measurement pipeline is provided with small nozzles, middle nozzles and large nozzles which are sequentially sleeved, the large nozzles are fixed in the inside of the measurement pipeline, the small nozzles and the middle nozzles are both slidably arranged in the inside of the measurement pipeline and are driven to slide by a driving mechanism for changing the gas flow cross section of the measurement pipeline.The wide-range air leakage amount detection device can cover all air leakage amount grades stipulated by new regulations and all air leakage amount grades stipulated by air valve standards, the detection conclusion is objective and fair, and the detection efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of air leakage detection technology, and more specifically to a wide-range air leakage detection device that includes minute flow rate measurement. Background Technology

[0002] 1. Regarding the wide measurement range requirement of the detection device

[0003] The "Technical Specification for Ventilation Ducts" JGJ / T 141-2017 (hereinafter referred to as the New Specification) proposes a method for specifying the allowable air leakage of ducts according to their leakage rate levels, referencing internationally accepted standards. Class E is a level even stricter than the internationally accepted standard. The air leakage rate levels and allowable air leakage rates specified in the New Specification are shown in Table 1.

[0004] Table 1. Air Leakage Rating and Allowable Air Leakage for Air Ducts

[0005]

[0006] Note: P is the static pressure limit value.

[0007] The "Building Ventilation Airflow Regulating Valves" standard JG / T 436-2014 (hereinafter referred to as the valve standard) specifies the valve body leakage level and allowable air leakage. The lowest allowable air leakage is Class A, as shown in Table 2.

[0008] Table 2 Valve Body Leakage Level and Permissible Air Leakage

[0009]

[0010] Note: P represents the static pressure being measured.

[0011] Tables 1 and 2 specify strict control over air leakage, with extremely low permissible leakage values ​​for high-sealing grades. When performing type testing on engineering ductwork, a test sample of 4.8 meters (4 sections of ductwork, each 1.2m in length) should be connected. According to Table 1, the lower limit of the measuring range of the testing device used to determine the duct leakage grade must be less than 0.42 m. 3 ·h -1 This is necessary to meet the Class E leakage rate test requirements for small-sized ducts; to meet the leakage rate test requirements for valve bodies under normal operating pressure, according to Table 2, the lower limit of the testing device's range must be as low as 0.01 m. 3 ·h -1 Only then can we have the ability to test small-sized valve bodies.

[0012] The maximum range of the testing device corresponds to the surface area of ​​the duct to be tested. To test as many ducts as possible at once, the upper limit of the range should generally be no less than 720 m for ducts with lower airtightness ratings. 3 ·h -1Only then can the needs of routine engineering testing be met.

[0013] Based on the above requirements, the detection range of the testing device should be 0.01 m under the specified detection pressure. 3 ·h -1 ~720m 3 ·h -1 In order to implement national standards in the construction supervision and final acceptance of actual projects, there is an urgent need for a wide-range leakage detection device with micro-flow measurement to determine the leakage level of air ducts and valves.

[0014] Currently, there are no duct leakage detection devices in China that meet the above requirements. Only a few companies offer simple leakage detection devices, and the lower limit of the detection range for these devices is 9.5 m. 3 ·h -1 The above methods cannot meet the requirements for testing the C, D, and E grade minor air leakage of small-diameter ducts according to the new regulations, nor can they be used to test the air leakage of valve bodies according to the valve standard requirements.

[0015] Because the permissible leakage values ​​for higher leakage levels stipulated in the new regulations are much lower than internationally accepted standards, leakage detection devices (range 1L / s~200L / s) currently manufactured by foreign companies can only detect Class C leakage in small-diameter ducts during type testing, and cannot meet the measurement requirements for Class D and E leakage in small-diameter ducts. Furthermore, foreign testing devices adhere to European and American standards and use imperial units that require conversion, making them unsuitable for use in domestic projects.

[0016] 2. Regarding the objectivity and impartiality of the test results from the testing device.

[0017] Given the lack of unified technical standards for air leakage detection devices, the new regulations can only provide general guidelines for their use, failing to address how to ensure objectivity and impartiality in the testing process and results. This leaves room for discretionary decisions by operators. Simple air leakage detectors rely on manual operation and visual readings, with operators selecting calculation methods based on their own understanding of the regulations and manually calculating the results. The testing and calculation process is highly subjective, susceptible to human error, and prone to errors from repeated operations by different individuals. Consequently, test results are often disputed and cannot serve as legally valid evidence for project completion and acceptance.

[0018] 3. Regarding the ease of use of the testing device

[0019] Currently, most air leakage detection devices use duct-type nozzle flow meters to detect the air volume entering the duct. The range of the duct-type nozzle flow meter is determined by the specifications of its internal nozzles. Therefore, in application, multiple duct-type nozzle flow meters with different nozzle specifications need to be prepared to meet different range requirements. When using them, the allowable air leakage of the duct under test needs to be calculated, and then the duct-type nozzle flow meter with the appropriate range is selected and connected and fixed to the automatic pressure stabilizing fan according to the allowable air leakage, which affects work efficiency.

[0020] Therefore, it is necessary to propose a wide-range air leakage detection device with micro-flow measurement to solve the above problems. Summary of the Invention

[0021] The purpose of this invention is to provide a wide-range air leakage detection device with micro-flow measurement. The whole machine complies with the standard traceability requirements. Its range is widened to cover all air leakage levels specified in the new regulations and all air leakage levels specified in the valve standards. It can also achieve automatic adjustment and detection on the engineering site. It can automatically compare the measured values ​​with the design air leakage level of the tested air duct and valve to fairly determine whether the test results are qualified.

[0022] Technical solution

[0023] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0024] A wide-range air leakage detection device with micro-flow measurement, characterized in that: it includes an air flow measuring device and an automatic pressure-stabilizing fan, wherein the air outlet of the air flow measuring device is connected to the air inlet of the automatic pressure-stabilizing fan;

[0025] The air flow measurement device includes a measuring pipe. Inside the measuring pipe are a small nozzle, a medium nozzle, and a large nozzle arranged in sequence. The large nozzle is fixed inside the measuring pipe. The small and medium nozzles are slidably arranged inside the measuring pipe and are driven by a drive mechanism to change the gas flow cross-section of the measuring pipe. A micro differential pressure sensor for detecting the pressure difference between the two ends of the measuring pipe is provided on the outside of the measuring pipe. A mass flow meter for measuring small flow rates is provided on the outside of the inlet end of the measuring pipe. The automatic pressure stabilizing fan includes an EC variable speed fan, a PLC controller, and a static pressure sensor, used to ensure that the measured air duct reaches and stably maintains a set detection static pressure limit value.

[0026] It also includes a touch screen, a temperature sensor, and an atmospheric pressure sensor. The mass flow meter, touch screen, differential pressure sensor, static pressure sensor, temperature sensor, and atmospheric pressure sensor are all connected to the PLC controller. The PLC controller is used to calculate and compare the measured values, and displays the measured air leakage and pass / fail judgment results of the tested air duct through the touch screen.

[0027] Furthermore, the automatic pressure-stabilizing ventilator also includes a fan static pressure box, and an EC variable speed fan is installed inside the fan static pressure box.

[0028] Furthermore, the small nozzle is fixed to the inside of the inner tube, and an orifice plate adapted to the inner diameter of the measuring pipe is fixedly connected to the outside of the inner tube.

[0029] Furthermore, the air inlet of the measuring pipe is connected to a sealing box via a T-junction pipe. The driving mechanism includes a first servo motor, a second servo motor, a first lead screw, and a second lead screw. The second lead screw passes through the orifice plate and is threadedly connected to the central nozzle. The first lead screw passes through the central nozzle and is threadedly connected to the orifice plate. The first lead screw is driven to rotate by the second servo motor, and the second lead screw is driven to rotate by the first servo motor. Both the first and second lead screws are rotatably connected to the sealing box. A limit ring is fixedly connected to the side of the large nozzle near the T-junction pipe. Both the first and second lead screws are rotatably connected to the limit ring.

[0030] Furthermore, there are two of each of the first and second lead screws. The two first lead screws are symmetrically distributed on both sides of the orifice plate, and the two second lead screws are symmetrically distributed on both sides of the nozzle.

[0031] Furthermore, sealing rings are fixedly connected to both sides of the nozzle.

[0032] Furthermore, the airflow measuring device has a range of 860m³ for detecting airflow. 3 ·h -1 ~0.006m 3 ·h -1 .

[0033] Furthermore, the tee is a T-shaped tee, and the measuring pipe and the sealing box are respectively connected to the two corresponding ports of the T-shaped tee.

[0034] Furthermore, both the air inlet end of the three-way pipe and the air outlet end of the EC variable speed fan are fixedly connected to corrugated hose connectors.

[0035] Beneficial effects

[0036] The beneficial effects of this invention are as follows:

[0037] 1. This invention sets up multiple nozzles of different specifications to meet the requirements of widening the flow range, and at the same time, it effectively measures minute air leakage by deploying mass flow meters.

[0038] 2. In this invention, the entire measurement process, including sampling, formula calculation, difference comparison, and qualification determination, is completed by the PLC controller, eliminating the need for manual reading and calculation. At the same time, it automatically determines whether the test results are qualified, ensuring the strict reliability of the whole machine's standard traceability and the objectivity and impartiality of the test conclusions.

[0039] 3. This invention allows the device to automatically calculate the allowable air leakage by inputting the diameter, length, and design leakage level of the duct being tested, and to automatically adjust the measuring pipe to the corresponding range based on the allowable air leakage. This eliminates the need for manual adjustment, making it more convenient to use and improving work efficiency. Attached Figure Description

[0040] Figure 1 This is a connection block diagram of the structure of the present invention;

[0041] Figure 2 This is a top view of the structure of the present invention;

[0042] Figure 3 This is a front view schematic diagram of the structure of the present invention;

[0043] Figure 4 This is a cross-sectional schematic diagram of the air flow measurement device of the present invention;

[0044] Figure 5 For the present invention Figure 4 Enlarged diagram of point A.

[0045] Reference numerals: 1. EC variable speed fan; 2. Fan static pressure box; 4. Measuring pipe; 5. T-joint; 6. Sealed box; 7. Test duct; 11. Mass flow meter; 12. Touch screen; 13. Micro differential pressure sensor; 14. Static pressure sensor; 15. Temperature sensor; 16. Atmospheric pressure sensor; 19. Moving platform; 20. Corrugated hose; 22. Corrugated hose connector; 23. Static pressure interface; 24. Corrugated hose interface; 30. First servo motor; 31. Second servo motor; 32. First lead screw; 33. Second lead screw; 34. Inner tube; 35. Small nozzle; 36. Orifice plate; 37. Medium nozzle; 38. Limit ring; 39. Large nozzle; 101. PLC controller. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1-5As shown, a wide-range air leakage detection device with micro-flow measurement is assembled on a mobile platform 19. It includes an air flow measurement device and an automatic pressure-stabilizing fan. The air outlet of the air flow measurement device is connected to the inlet of the static pressure box 2 of the fan, and is used to measure the air flow entering the EC variable speed fan 1.

[0049] The air flow measurement device includes three long-diameter nozzles. All three long-diameter nozzles are designed and manufactured in accordance with GB / T 2624-93 "Flow Measurement Throttling Devices for Measuring the Flow Rate of Fluids Filling Circular Pipes". According to different measurement ranges, three specifications of nozzles are designed: large nozzle 39, medium nozzle 37, and small nozzle 35. The small nozzle 35 is fixed inside the inner tube 34. The outer side of the inner tube 34 is fixedly connected to an orifice plate 36 that matches the inner diameter of the measuring pipe 4. The structural cooperation between the small nozzle 35 and the inner tube 34 allows even a small amount of air flowing through the small nozzle 35 to be detected.

[0050] All three nozzles are built into the measuring pipe 4 of the D100. The small nozzle 35, medium nozzle 37, and large nozzle 39 are sequentially nested together. The large nozzle 39 is fixed inside the measuring pipe 4, while the small nozzle 35 and medium nozzle 37 are slidably arranged inside the measuring pipe 4 and driven by a drive mechanism. By adjusting the nesting state of the nozzles, the gas flow cross-section of the measuring pipe 4 is changed to achieve graded adjustment of different measuring ranges, covering a total air volume range of 860 m³. 3 ·h -1 ~0.006m 3 ·h -1 The various measurement ranges are interconnected and overlap. When using them, the range can be adjusted to a suitable range according to the allowable air leakage range of the duct being measured 7.

[0051] A micro differential pressure sensor 13 is provided on the outside of the measuring pipe 4 to detect the pressure difference between the two ends of the measuring pipe 4. The PLC controller 101 is connected to the output end of the micro differential pressure sensor 13. The input end of the micro differential pressure sensor 13 is connected to the differential pressure output interface on the measuring pipe 4 through the differential pressure test hose. According to the pressure difference value before and after the flow meter collected by the micro differential pressure sensor 13, the PLC controller 101 automatically calculates the air volume through the measuring pipe 4 according to the preset rules. This air volume is the leakage volume of the measured air duct 7.

[0052] A mass flow meter 11 for measuring minute flow rates is installed on the outside of the inlet end of the measuring pipe 4. Through automatic switching of continuous measurement, flow rates as low as 0.006 m³ / s can be achieved. 3 ·h -1 Minimal flow measurement.

[0053] The automatic pressure-stabilizing fan includes an EC variable speed fan 1, a PLC controller 101, and a static pressure sensor 14. The PLC controller 101 is connected to the output terminal of the static pressure sensor 14, and the input terminal of the static pressure sensor 14 is connected to the static pressure interface 23 reserved in the tested duct 7 through a static pressure test hose. The automatic pressure-stabilizing fan compares the static pressure measured by the static pressure sensor 14 with the set value through the PLC controller 101, and issues a speed change command according to the deviation to automatically adjust the speed of the EC variable speed fan 1 so that the static pressure in the tested duct 7 reaches the detected static pressure limit value and stabilizes within the preset allowable range of static pressure fluctuation.

[0054] In this embodiment, the specific operation process is as follows:

[0055] Flow meter selection:

[0056] After the PLC controller 101 and the touch screen 12 are powered on, the allowable air leakage of the tested air duct 7 is calculated and displayed based on the pipe diameter, length and design leakage level of the tested air duct 7 input by the human-machine interface. At the same time, the PLC controller 101 controls the movement of the small nozzle 35 and the medium nozzle 37 by controlling the drive device, and adjusts the nozzles used by the air flow measuring device to adjust the measuring pipe 4 to a suitable range.

[0057] Connecting devices:

[0058] Seal both ends and all branches and air outlets of the duct under test 7. Connect the pre-reserved corrugated hose interface 24 on the duct under test 7 to the corrugated hose connector 22 of the measuring device through the corrugated hose 20. During positive pressure testing, connect the corrugated hose 20 to the outlet of the fan static pressure box 2. During negative pressure testing, connect the corrugated hose 20 to the inlet of the tee pipe 5. Then connect the static pressure sensor 14 to the pre-reserved static pressure interface 23 of the duct under test 7 through the static pressure test hose according to the positive and negative markings.

[0059] Measurement preparation:

[0060] On the human-machine interface of the touch screen 12, confirm the input of the pipe diameter, length and the design allowable leakage level (A, B, C, D, E) of the tested air duct 7 selected in the drop-down menu, the pressure type (positive or negative pressure), the test static pressure limit value, set the test static pressure fluctuation allowable value, and set the sampling time.

[0061] Measurement process:

[0062] After starting the EC variable speed fan 1, and waiting for the static pressure inside the duct to reach the set detection static pressure limit and stabilize within the allowable static pressure fluctuation range, the airflow detection device automatically begins to cumulatively detect the air passing through the measuring pipe 4 (i.e., the duct leakage) according to the set sampling time, and calculates the duct leakage according to the preset program. Simultaneously, based on the values ​​collected by the atmospheric pressure sensor 16 and temperature sensor 15, the detection data is corrected for standard conditions. The PLC controller 101 performs logical analysis according to various engineering conditions specified in the standards or new regulations, automatically selects the corresponding calculation method, and compares it with the preset allowable leakage standard value for this level. Finally, the measured leakage value (m³) of the tested duct 7 is displayed on the touch screen 12 interface. 3 ·h -1 ·m -2 The system will then provide a "qualified" or "unqualified" test result.

[0063] The duct leakage test procedure is strictly implemented in accordance with current national standards. The entire process, including sampling, formula calculation, difference comparison, and pass / fail determination, is guided by the PLC controller 101 according to a preset program. The final result is displayed directly on the touch screen 12. The entire process is closed-loop and automatic, requiring no manual reading or calculation. There is no possibility of human factors affecting the test results, ensuring the strict and reliable traceability of the entire machine. The test results are objective and fair and can serve as the legal basis for project completion and handover.

[0064] The program uses the following flow calculation formula:

[0065] Air leakage rate of duct under standard conditions:

[0066] The air volume entering the duct is calculated by measuring the pressure difference before and after pipe 4, which is the air leakage of the duct. The measurement result is the weighted average of the sampled air volume per unit time.

[0067] Basic formula:

[0068] In the formula: q—air leakage rate of the duct, m 3 ·h -1 ·m -2 ;

[0069] d—Standard nozzle throat diameter, in meters;

[0070] Δp — Pressure difference across the flow meter, Pa;

[0071] ρ — specific weight of air, kg·m -3 ;

[0072] α — Nozzle (orifice plate) flow coefficient;

[0073] S — Surface area of ​​the duct to be measured, m² 2 ;

[0074] The air leakage rate of the tested duct 7 displayed on the touchscreen 12 interface should be the air volume under standard conditions (101325 Pa, 20℃) after correction for air density. The specific correction formula is as follows:

[0075]

[0076] Where: Pb—Atmospheric pressure measured by atmospheric pressure sensor 16, Pa;

[0077] t——Air temperature measured by temperature sensor 15, °C.

[0078] Example 2

[0079] like Figure 4 and 5 As shown, this embodiment is a further optimization based on embodiment 1.

[0080] Specifically, the air inlet of the measuring pipe 4 is connected to a sealing box 6 via a three-way pipe 5. The driving mechanism includes a first servo motor 30, a second servo motor 31, a first lead screw 32, and a second lead screw 33. The second lead screw 33 passes through the orifice plate 36 and is threadedly connected to the central nozzle 37. The first lead screw 32 passes through the central nozzle 37 and is threadedly connected to the orifice plate 36. The first lead screw 32 is driven to rotate by the second servo motor 31, and the second lead screw 33 is driven to rotate by the first servo motor 30. Both the first lead screw 32 and the second lead screw 33 are rotatably connected to the sealing box 6. A limit ring 38 is fixedly connected to the side of the large nozzle 39 near the three-way pipe 5. Both the first lead screw 32 and the second lead screw 33 are rotatably connected to the limit ring 38.

[0081] Specifically, there are two first lead screws 32 and two second lead screws 33. The two first lead screws 32 are symmetrically distributed on both sides of the orifice plate 36, and the two second lead screws 33 are symmetrically distributed on both sides of the nozzle 37.

[0082] Specifically, toothed pulleys are fixedly connected to the ends of the first lead screw 32 and the second lead screw 33 near the sealing box 6, as well as to the output shafts of the first servo motor 30 and the second servo motor 31. The first servo motor 30 is connected to the second lead screw 33 by a synchronous belt drive, and the second servo motor 31 is connected to the first lead screw 32 by a synchronous belt drive.

[0083] Specifically, sealing rings are fixedly connected to both sides of the middle nozzle 37.

[0084] Specifically, the tee pipe 5 is a T-shaped tee pipe, and the measuring pipe 4 and the sealing box 6 are respectively connected to the two corresponding ports of the T-shaped tee pipe.

[0085] In this embodiment, the diameter, length and designed leakage level of the tested air duct 7 are input through the human-machine interface of the touch screen 12. The PLC controller 101 calculates and displays the allowable leakage of the tested air duct 7 through the touch screen 12. Then, the PLC controller 101 controls the first servo motor 30 and the second servo motor 31 to start and stop, and controls the small nozzle 35 and the medium nozzle 37 to slide, so that the air flow measuring device reaches the range corresponding to the allowable leakage.

[0086] For example, if the calculated allowable air leakage is within the range of the nozzle 37 in the air flow measurement device application, then the second servo motor 31 drives the first lead screw 32 to rotate. Under the action of the first lead screw 32, the orifice plate 36 is driven to move towards the sealing box 6, and the inner tube 34 passes over the air inlet of the tee pipe 5 to avoid affecting the air intake. At the same time, the first servo motor 30 drives the second lead screw 33 to rotate. Under the action of the second lead screw 33, the middle nozzle 37 is driven to move towards the large nozzle 39 and engage. At the same time, under the action of the sealing ring, the edges of the middle nozzle 37 and the large nozzle 39 are sealed, so that the gas passing through the measuring pipe 4 passes through the middle nozzle 37, thereby automatically completing the adjustment of the range.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A wide range air leakage detection device with micro flow measurement, characterized in that: The air flow measuring device and the automatic constant pressure ventilator are connected, and the air flow measuring device is connected with the air inlet of the automatic constant pressure ventilator. The air flow measuring device comprises a measuring pipe (4), the inside of the measuring pipe (4) is provided with a small nozzle (35), a middle nozzle (37) and a large nozzle (39) which are sequentially sleeved, the large nozzle (39) is fixed in the inside of the measuring pipe (4), the small nozzle (35) and the middle nozzle (37) are both slidably arranged in the inside of the measuring pipe (4) and are driven to slide by a driving mechanism for changing the gas flow cross section of the measuring pipe (4), the two side edges of the middle nozzle (37) are both fixedly connected with sealing rings, the outside of the measuring pipe (4) is provided with a micro differential pressure sensor (13) for detecting the differential pressure between the two ends of the measuring pipe (4), and the inlet end of the measuring pipe (4) is provided with a mass flow meter (11) for measuring a small flow. The small nozzle (35) is fixed to the inside of an inner pipe (34), the outside of the inner pipe (34) is fixedly connected with a hole plate (36) which is matched with the inner diameter of the measuring pipe (4), the air inlet of the measuring pipe (4) is connected with a sealing box (6) through a tee pipe (5), the driving mechanism comprises a first servo motor (30), a second servo motor (31), a first screw rod (32) and a second screw rod (33), the second screw rod (33) penetrates through the hole plate (36) and is threadedly connected with the middle nozzle (37), the first screw rod (32) penetrates through the middle nozzle (37) and is threadedly connected with the hole plate (36), the first screw rod (32) is driven to rotate by the second servo motor (31), the second screw rod (33) is driven to rotate by the first servo motor (30), the first screw rod (32) and the second screw rod (33) are both rotationally connected with the sealing box (6), and the large nozzle (39) is fixedly connected with a limiting ring (38) on the side close to the tee pipe (5). The automatic constant pressure ventilator comprises an EC variable speed fan (1), a PLC controller (101) and a static pressure sensor (14), so that the detected air pipe (7) can reach and stably maintain the set detection static pressure limit value. The automatic constant pressure ventilator further comprises a touch screen (12), a temperature sensor (15) and an atmospheric pressure sensor (16), and the mass flow meter (11), the touch screen (12), the micro differential pressure sensor (13), the static pressure sensor (14), the temperature sensor (15) and the atmospheric pressure sensor (16) are all connected with the PLC controller (101).

2. The wide range air leakage detection device with micro flow measurement according to claim 1, characterized in that: The automatic constant pressure ventilator further comprises a fan static pressure box (2), and the EC variable speed fan (1) is installed in the inside of the fan static pressure box (2).

3. A wide range air leakage detection device with micro flow measurement according to claim 1, characterized in that: The first screw rod (32) and the second screw rod (33) are both two, the two first screw rods (32) are symmetrically distributed on the two sides of the hole plate (36), and the second screw rods (33) are symmetrically distributed on the two sides of the middle nozzle (37).

4. The wide range air leakage detection device with micro flow measurement according to claim 1, characterized in that: The air flow measuring device detects the range of the air volume of 860m 3 ·h -1 ~ 0.006m 3 ·h -1 .

5. A wide range air leakage detection device with micro flow measurement according to claim 1, characterized in that: The tee pipe (5) is a T-shaped tee pipe, and the measuring pipe (4) and the sealing box (6) are connected with two pipe openings of the T-shaped tee pipe respectively.

6. A wide range air leakage detection device with micro flow measurement according to claim 1, characterized in that: The air inlet end of the tee pipe (5) and the air outlet end of the EC variable speed fan (1) are fixedly connected with corrugated hose joints (22).

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