A modular aerosol impactor cut-point calibration system based on constant rate sampling principle

Abstract

This invention provides a modular aerosol impactor cut particle size calibration system based on the isokinetic sampling principle, belonging to the field of aerosol measurement technology. It includes a downstream isokinetic sampling module, a mass flow control module, an upstream control sampling module, and an aerosol mixing module. The aerosol mixing module is connected to both the upstream control sampling module and the downstream isokinetic sampling module. Both modules are connected to a particle size analyzer probe. The downstream isokinetic sampling module is connected to the mass flow control module and includes a cut particle size calibration device. The sample obtained by the measuring instrument of this invention can accurately represent the upstream inlet concentration of the impactor to be calibrated. The downstream isokinetic sampling module enables isokinetic sampling under varying conditions, effectively avoiding diffusion losses caused by eddies, reducing particle bounce caused by wall thickness, and improving the calibration accuracy of the impactor cut particle size.

Description

Technical Field

[0001] This invention belongs to the field of aerosol measurement technology, specifically relating to a modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle. Background Technology

[0002] The aerosol impactor is a core device for atmospheric particulate matter classification and detection based on the aerodynamic inertial classification principle. Accurate calibration of its cut-off particle size (the particle size corresponding to 50% collection efficiency) is crucial to ensuring the reliability of monitoring data. Currently, there are two main methods for calibrating the cut-off particle size of aerosol impactors: the mass calibration method based on weighing monodisperse dust and filter membranes (and the upstream and downstream sampling method based on polydisperse dust and particle size spectrometers (such as the TSI 3321). The former suffers from drawbacks such as high cost, long testing time, complex operation, and large footprint of the testing equipment. The latter addresses these issues: the upstream and downstream sampling method based on polydisperse dust and particle size spectrometers compares upstream and downstream particle size spectra and compares the quantity concentration corresponding to each particle size channel downstream with the quantity concentration of the same particle size channel upstream. This yields the dust transmission efficiency corresponding to each particle size channel, which serves as the performance evaluation index for aerosol impactor particle size classification, i.e., the cut-off efficiency. The curve formed by each cut-off efficiency point is the cut-off efficiency curve. The required cutting particle size is the particle size corresponding to 50% efficiency on the curve. This method can determine the cutting particle size of the aerosol impactor in a single test, reducing the testing time from a week to half an hour, thus improving testing efficiency. Furthermore, the device is compact and easy to operate, making this method the mainstream testing approach. However, this mainstream testing method has inherent limitations. The accuracy of the upstream and downstream particle size distributions directly affects the accuracy of the aerosol impactor's cutting particle size calibration. Therefore, the scientific design of the device structure for obtaining the upstream and downstream particle size distributions becomes a key factor influencing the accurate measurement of the particle size distribution.

[0003] Existing aerosol impactor cutting particle size calibration devices based on upstream and downstream sampling are mainly divided into two categories:

[0004] I. Lateral Branch Sampling (T-junction Diversion Type): This method has a simple structure, with only a T-junction connected in series on the upstream and downstream main pipelines of the structure under test. Aerosol samples are directly extracted from the branch pipe opening provided by the T-junction, which is perpendicular to the main pipeline. This method assumes that the sample obtained from the branch pipe opening can represent the real aerosol sample. However, experimental results show that the aerodynamic behavior of particulate matter is affected by the inertia of the particulate matter itself. When sampling from the branch pipe, among the different sizes of particulate matter contained in the original main pipeline, due to the inertial effect of the particulate matter, small-diameter particles can be deflected into the branch pipe better with the airflow, while most large-diameter particles will maintain their original trajectory due to inertia. This results in a serious lack of large particles in the sample obtained from the branch pipe, making it difficult to accurately restore the particle size distribution of the real aerosol.

[0005] II. Duct-clamped type: Based on the duct structure, the device under test is clamped for upstream and downstream sampling. It emphasizes the installation of right-angle sampling tubes in the upstream and downstream to obtain upstream and downstream aerosol samples. Compared with the first method, this method avoids the loss of large-sized particles caused by lateral sampling, but introduces five new problems: (1) Directly extracting samples from the upstream sample flow will result in a loss of total aerosol volume. When the sampling flow rate is 5 L / min and the total working flow rate is only 10 L / min, the loss of total aerosol volume will be more significant; (2) Placing the sampling tube in the upstream flow field will inevitably affect the upstream flow field, resulting in distortion of the obtained aerosol samples; (3) Excessive wall thickness at the end face of the sampling tube will cause excessive loss of large-diameter aerosol particles. The sampling tube structure mentioned in the article will significantly affect the intrinsic restoration of aerosols; (4) With fixed sampling tube and duct dimensions, once the working flow rate is changed, the flow velocity inside the sampling tube will not match the flow velocity in the duct, resulting in aerosol particles. There is inlet loss, and the loss share is proportional to the sample particle size; (5) Since particles have greater inertia than airflow, the direction of airflow and the entrained particles will change asynchronously at the bend of the right-angle sampling tube, causing the particles to break away from the airflow streamline and impact the tube wall to cause inertial deposition loss. Moreover, the loss share changes with the sampling flow rate and particle size. Therefore, this method is difficult to uniformly evaluate the loss share through a single experiment under different flow conditions, and it is even more difficult to restore the particle size distribution of aerosol samples.

[0006] In summary, the above two schemes have the following shortcomings: (1) Branch sampling with air extraction results in severe loss of large-diameter particles and shift in the peak value of particle size distribution; (2) When sampling upstream, air extraction will cause a loss of total aerosol volume, resulting in inaccurate total volume collected by the impactor; (3) The upstream sampling structure has an impact on the flow field, making it difficult to restore the true particle size distribution upstream; (4) The unthinned pipe wall will cause severe deposition and bounce of large-diameter particles at the pipe opening, making it difficult to meet the requirements for fine sample restoration; (5) The flow rate adaptation range is narrow; (6) The right-angled sampling pipe has severe inertial deposition loss. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned technical problems by providing a modular aerosol impactor cutting particle size calibration system based on the principle of isokinetic sampling.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle includes: a downstream isokinetic sampling module, a mass flow control module, an upstream control sampling module, and an aerosol mixing module. The aerosol mixing module is connected to the upstream control sampling module and the downstream isokinetic sampling module, respectively. The upstream control sampling module and the downstream isokinetic sampling module are respectively connected to a particle size spectrometer probe. The downstream isokinetic sampling module is connected to the mass flow control module. The downstream isokinetic sampling module includes a cutting particle size calibration device.

[0010] Furthermore, the cutting particle size calibration device includes an upper end cover, an aerosol cascade impactor installed between the upper end cover and the sleeve, the sleeve is mounted on a base, an outer sleeve is installed in the middle of the upper surface of the base, the outer sleeve is connected to a flow regulating pipe elbow, the flow regulating pipe elbow is connected to a flow regulating pipe, the lower end of the flow regulating pipe elbow is connected to an isokinetic sampling pipe, the isokinetic sampling pipe is connected to a quick-connect connector, and the rear end of the flow regulating pipe is provided with a right-angle thread to connect to a reducing connector.

[0011] Furthermore, the lower end of the elbow is provided with a light hole, and a through-plate sleeve is welded inside the light hole. The axis of the through-plate sleeve coincides with the axis of the central hole of the base.

[0012] Furthermore, the isokinetic sampling tube includes an inner sleeve, and an isokinetic sampling head is installed at the inlet of the inner sleeve.

[0013] Furthermore, the isokinetic sampling head is a detachable thin-walled sampling head with an inner-outer diameter ratio of less than 1.1.

[0014] Furthermore, the upper inlet face of the outer sleeve is higher than the upper inlet face of the inner sleeve.

[0015] Furthermore, multiple adjustable support legs are installed at the bottom of the base.

[0016] Furthermore, the flow control module includes a pressure transmitter and a mass flow controller. Flow limiting ball valve one and flow limiting ball valve two are installed on the inflow and outflow sides of the mass flow controller, respectively. The outflow side pipeline of flow limiting ball valve two is connected to oil-free vacuum pump one and oil-free vacuum pump two, which are connected in parallel. The pipeline between flow limiting ball valve two and oil-free vacuum pump one is connected to a branch with a supplementary ball valve installed. The supplementary ball valve is open to the atmosphere. By adjusting the valve opening, the flow fluctuation caused by the vacuum pump is reduced. The pressure transmitter is installed on the branch between the flow regulating pipe and flow limiting ball valve one to monitor the rise and fall of the pressure of the aerosol cascade impactor.

[0017] Furthermore, the aerosol mixing module includes an aerosol mixing container, which is connected to a stable aerosol generation source.

[0018] Furthermore, the pipelines of the upstream control sampling module and the downstream isokinetic sampling module are set up in parallel with consistent geometry and arrangement.

[0019] The beneficial effects of this invention are as follows:

[0020] The aerosol mixing module of this invention has a sufficiently large space, which greatly extends the calibration time and absorbs occasional fluctuations in the aerosol generation rate, thereby creating a uniform, stable, and sufficient aerosol environment required by the device to be calibrated, ensuring the accuracy of upstream sampling.

[0021] The upstream control sampling module of this invention uses a control approach to arrange two identical sampling pipelines in parallel, thus avoiding interference between the upstream sampling flow rate and the total sampling flow rate.

[0022] The upstream control sampling module of this invention allows the influence of sampling port loss and pipeline transport loss during aerosol transport to be ignored. Only the sample obtained from the pipeline outlet is used as the test sample. This avoids the influence of the upstream sampling structure on the flow field and also ignores the influence of peak offset phenomenon, realizing that what is measured is what is obtained, that is, the outlet gas at the end of the pipeline is the test sample. This ensures that the sample entering the measuring instrument is consistent with the sample entering the inlet of the impactor to be calibrated. In other words, the sample obtained by the measuring instrument can accurately represent the upstream inlet concentration of the impactor to be calibrated.

[0023] The downstream isokinetic sampling module of this invention adopts several technical details such as a streamlined tapered structure, thin-walled sampling head, and sleeve structure, which realizes isokinetic sampling under varying scenarios, effectively avoids diffusion loss caused by eddies, reduces particle bounce caused by wall thickness, and improves the calibration accuracy of the impactor cutting particle size.

[0024] The modular design of the sampling head used in this invention extends the flow adaptability of the device.

[0025] The straight pipe design and vertical arrangement adopted in this invention avoid inertial deposition loss and gravity deposition loss during the sampling process. Attached Figure Description

[0026] Appendix Figure 1 A schematic diagram of the structure of this invention;

[0027] Appendix Figure 2 An assembly diagram of the cutting particle size calibration device of the present invention;

[0028] Appendix Figure 3 Top view of the cutting particle size calibration device of the present invention;

[0029] Appendix Figure 4Left view of the cutting particle size calibration device of the present invention;

[0030] Appendix Figure 5 It is attached Figure 4 AA sectional view.

[0031] In the attached diagram: 1. Downstream isokinetic sampling module; 101. Upper end cap; 102. Aerosol cascade impactor; 103. Sleeve; 104. Base; 105. Isokinetic sampling head; 106. Isokinetic sampling tube; 107. Quick-connect connector; 108. Flow regulating tube elbow; 109. Flow regulating tube; 110. Reducer; 111. Support leg; 112. Outer sleeve; 113. Inner sleeve.

[0032] 2. Mass flow control module, 201. Pressure transmitter, 202. Flow limiting ball valve one, 203. High efficiency filter, 204. Mass flow controller, 205. Flow limiting ball valve two, 206. Oil-free vacuum pump one, 207. Oil-free vacuum pump two, 208. Repair ball valve, 3. Upstream control sampling module, 4. Aerosol mixing module. Detailed Implementation

[0033] The present invention will now be further described with reference to the accompanying drawings.

[0034] This invention provides a modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle, as shown in the attached figure. Figure 1 As shown, it includes: a downstream isokinetic sampling module 1, a mass flow control module 2, an upstream control sampling module 3, and an aerosol mixing module 4. The aerosol mixing module 4 is connected to the upstream control sampling module 3 and the downstream isokinetic sampling module 1, respectively. The upstream control sampling module 3 and the downstream isokinetic sampling module 1 are respectively connected to a particle size analyzer probe. The downstream isokinetic sampling module 1 is connected to the mass flow control module 2. The downstream isokinetic sampling module 1 includes a particle size calibration device.

[0035] The upstream control sampling module 3 is used to accurately collect upstream sample parameters. It employs a control approach, setting up two identical sampling pipes, each connected upstream to an aerosol mixing container. The aerosols within the container are drawn into the structures connected to their respective ends. One sampling pipe is connected to an aerosol particle size analyzer probe, and the other is connected to a downstream isokinetic sampling module 1, which is also connected to the aerosol particle size analyzer probe. Because the pipe structure and arrangement are identical, the aerosol loss fraction is the same in both control pipes. This ensures that the sample entering the measuring instrument is the same as the sample entering the downstream isokinetic sampling module, meaning the sample obtained by the measuring instrument can represent the upstream concentration of the impactor to be calibrated.

[0036] The upstream control sampling module focuses on using stainless steel sampling tubes that are free of bends (or have a bend angle of less than 10°) and well grounded to minimize inertial deposition losses caused by bends and electrostatic losses caused by the tube wall material. Furthermore, the upstream sampling module mainly comprises two sampling tubes arranged in a parallel control configuration with identical geometry and layout to ensure consistent loss proportions between the two tubes. No valves are installed along the pipeline to reduce aerosol losses caused by flow obstruction.

[0037] The flow control module 2 is used to adjust the flow rate to adapt to the varying operating flow rate required by the impactor to be calibrated. This module includes a vacuum pump that provides the flow driving force, a mass flow controller that controls the additional flow rate, and other auxiliary structures and piping. By adjusting the mass flow controller, rapid control of the impactor's operating flow rate is achieved.

[0038] In this embodiment, the flow control module includes a pressure transmitter 201, a flow-limiting ball valve 202, a high-efficiency filter 203, a mass flow controller 204, a flow-limiting ball valve 205, an oil-free vacuum pump 206, an oil-free vacuum pump 207, and a supplementary ball valve 208. Each component is connected to the pipeline via threaded fittings or quick-connect fittings. The flow-limiting ball valve 202 and the flow-limiting ball valve 205 are installed on the inflow and outflow sides of the mass flow controller 204, respectively. The outflow side pipeline of the flow-limiting ball valve 205... The flow control module is connected to two oil-free vacuum pumps, 206 and 207, which are connected in parallel. The pipeline between the flow limiting ball valve 205 and the oil-free vacuum pump 206 is connected to a branch line equipped with a supplementary ball valve 208, which is open to the atmosphere. By adjusting the valve opening, the flow fluctuation caused by the vacuum pumps is reduced. The pressure transmitter 201 is installed on the branch line between the flow regulating pipe 109 and the flow limiting ball valve 202 to monitor the pressure rise and fall of the aerosol cascade impactor 102. The flow control module is connected to the cutting particle size calibration device via a pipeline and a variable diameter threaded ferrule, and is located downstream of the cutting particle size calibration device.

[0039] Furthermore, the mass flow controller 204 included in the flow control module can autonomously adjust the valve opening based on the internal electromagnetic regulating valve according to the PID structure, thereby ensuring that the flow rate is stable near the preset value. Flow limiting ball valve 202 and flow limiting ball valve 205 are installed on the inflow and outflow sides of the mass flow controller 204 to share the gas pressure drop of the mass flow controller 204. Oil-free vacuum pump 206 and oil-free vacuum pump 207 are connected in parallel to increase the maximum flow rate that can be provided. The high vacuum after their parallel connection creates a large pressure drop in the airflow path, at a flow rate of 30 L / min. At the above working flow rate, the mass flow controller 204 may reach the critical flow state due to the reduced opening of the internal valve. At this time, the flow reading is no longer reliable, and the working flow through the cutting particle size calibration device is no longer adjustable. Therefore, flow limiting ball valve 1 202 and flow limiting ball valve 205 are set to increase the pressure drop along the pipeline and keep the flow at the mass flow controller position below the critical flow level. The branch where the supplementary ball valve 208 is located is directly connected to the atmosphere. By adjusting the valve opening, the flow fluctuation caused by the vacuum pump can be reduced.

[0040] The aerosol mixing module 4 is used to provide the required aerosol sample. It includes an aerosol mixing container with a sufficiently large internal gas space and an aerosol stable generation source. At the start of calibration, the aerosol stable generation source delivers aerosol into the aerosol mixing container at a set generation rate. The aerosol is injected from the top of the mixing container, thereby forming a large number of uniform aerosol samples in the space, which are sufficient for the calibration experiment.

[0041] The aerosol mixing container is a sealed stainless steel pressure vessel with a large overall internal volume. It can be designed according to experimental requirements and has the capability for high-temperature, high-pressure, and long-cycle experiments. The aerosol generator included in this module can control different delivery rates and aerosol sample properties by adjusting the back pressure of the supplied carrier gas and the parameters of the added dust type.

[0042] As attached Figure 2-5 As shown, the downstream isokinetic sampling module 1 consists of an upper end cover 101, an aerosol cascade impactor 102, a sleeve 103, a base 104, an isokinetic sampling head 105, an isokinetic sampling tube 106, a quick-connect connector 107, a flow regulating tube elbow 108, a flow regulating tube 109, a reducing connector 110, and a support leg 111, which are connected in sequence.

[0043] As attached Figure 2-5As shown, the upper end cap 101 is connected to the aerosol cascade impactor 102 and the upper end face of the sleeve 103 by six M6 manganese steel bolts. The components are separated from each other by silicone gaskets to ensure airtightness. The sleeve 103 and the base 104 are also connected by six M6 manganese steel bolts. The manganese steel bolts are used for connection, and a silicone gasket is placed between them to ensure airtightness. An outer sleeve 112 is provided in the middle of the upper surface of the base 104. The outer sleeve 112 is preferably a stepped metal tube, which ensures that the loss is minimized when the aerosol flowing from top to bottom inside the sleeve 103 enters the converging section. The lower part of the outer sleeve 112, that is, the lower port of the base 104, is provided with a tapered external thread, which is used to connect with the flow regulating pipe elbow 108. The lower end of the flow regulating pipe elbow 108 is provided with a light hole, and a through plate sleeve is welded in the hole so that the axis of the sleeve coincides with the axis of the central hole of the base 104. The isokinetic sampling tube 106 is connected to the through plate sleeve and the extension length can be adjusted to cope with different flow states in the central metal tube of the base 104.

[0044] The isokinetic sampling tube 106 includes an inner sleeve 113, and a detachable sampling head 105 is sleeved at the inlet of the inner sleeve 113. The isokinetic sampling head 105 is a detachable thin-walled sampling head with an inner-outer diameter ratio of less than 1.1.

[0045] The aerosol flow rate inside the airflow passage formed by the stepped metal tube, flow regulating tube elbow 108, and flow regulating tube 109 in the middle of the base 104 accounts for a larger proportion than the total flow rate flowing into the stepped metal tube. The remaining small portion of the flow rate, while flowing along the inlet axis of the stepped metal tube, enters the flow channel formed by the isokinetic sampling head 105 and isokinetic sampling tube 106 in the coaxial direction while maintaining a constant flow velocity. The ratio of the volumetric flow rate in this flow channel to the volumetric flow rate of the remaining airflow is proportional to the flow channel area of ​​the two channels, ensuring the isokinetic conditions of the airflow at the airflow separation interface, thereby obtaining a representative sample with the same concentration as the downstream of the impactor to be calibrated.

[0046] Furthermore, the isokinetic sampling head 105 and the isokinetic sampling tube 106 are interference-fitted, and the joint is filled with sealant. The isokinetic sampling head 105 can also be configured as a detachable sampling head.

[0047] The front end of the flow regulating pipe 109 is provided with a tapered external thread to connect with the flow regulating pipe elbow 108, and the rear end of the flow regulating pipe 109 is provided with a right-angle thread to connect with the reducing fitting 110.

[0048] The base 104 is connected to each of the three adjustable-length support legs 111 by two M6 manganese steel bolts.

[0049] The downstream isokinetic sampling module 1 is used to accurately collect downstream sample parameters. It adopts an optimized streamlined tapered flow channel to guide the aerosol from the outlet of the impactor to be calibrated into the double-layer sleeve structure in a low-loss transport manner. The double-layer sleeve structure is arranged in a coaxial vertical manner. The upper inlet end face of the outer sleeve 112 is higher than the upper inlet end face of the inner sleeve 113, so that the total flow can have sufficient flow development time after entering the outer sleeve before reaching the inlet end face of the inner sleeve. Then it is split into the downstream sampling flow guided by the inner sleeve and the additional flow guided by the inner and outer interlayer annular space. The sum of the flow rates of the above two airflows is the total flow rate of the impactor outlet to be calibrated, that is, the working flow rate. By reasonably setting the diameter of the inner and outer sleeves, the flow velocities of the sampling flow and the additional flow are equal, so that the aerosol loss at the inlet end face of the inner sleeve is minimized.

[0050] The inner sleeve 113 is arranged vertically to eliminate the loss caused by gravity deposition. The inlet of the inner sleeve is fitted with a detachable thin-walled sampling head with an inner-outer diameter ratio of less than 1.1. The inner sleeve is a straight tube with a constant inner diameter. The straight tube design avoids the loss of aerosol inertial deposition caused by flow channel bends, so that the sampling flow can truly reflect the information of the downstream aerosol sample of the impactor to be calibrated.

[0051] In the downstream isokinetic sampling module, the inner sampling tube introduces the aerosol sample vertically downwards into the precision particle size analyzer with extremely low loss. The remaining flow is diverted at the sampling tube port in an isokinetic manner and then guided by the annular cavity between the inner and outer layers. It then flows sequentially through the flow regulating tube elbow, the flow regulating tube, and the reducer, and is finally discharged after being treated by the filter exhaust gas.

[0052] Working principle:

[0053] The calibration process first requires generating a stable aerosol sample, adjusting the high-pressure gas source to 0.4 MPa, turning on the aerosol generator (such as TOPAS SAG 410), adding polydisperse silica dust, and installing and connecting the aerosol impactor calibration device and the flow control module. During installation, the upper end cover 101 and the aerosol cascade impactor 102 are tightened diagonally with six M6 manganese steel bolts to a torque of 12 N·m (GB / T 16823.1-2010 standard). The airtightness test is performed according to GB / T In accordance with standard 26125-2011, maintain pressure at a differential pressure of 1 kPa for 30 minutes, then start oil-free vacuum pump 206 and oil-free vacuum pump 207, turn on and adjust mass flow controller 204 to achieve the working flow rate of the aerosol impactor. If its reading cannot reach the working flow rate requirement, adjust flow limiting ball valve 202 and flow limiting ball valve 205, slowly reducing their openings one by one, and slowly open supplementary ball valve 208 until the reading of mass flow controller 204 reaches the preset working flow rate value. Then start collecting the upstream and downstream concentrations of the aerosol impactor calibration device.

[0054] First, the aerosol environment (i.e., inlet concentration) at the front end of the upper cover 101 is tested, and the data from the aerodynamic particle size analyzer (such as the TSI 3321 model) is recorded. Then, the aerosol aerodynamic particle size analyzer inlet is connected to the lower end of the quick-connect connector 107 to sample and measure the downstream concentration of the aerosol impactor calibration device. At this time, the above flow rate adjustment process needs to be repeated so that the sum of the aerodynamic particle size analyzer sampling flow rate and the mass flow controller 204 is the working flow rate of the aerosol impactor.

[0055] After calibration, the downstream concentration data and upstream concentration data of the aerodynamic particle size spectrometer are compared one by one according to the particle size channel to obtain the cutting efficiency of the aerosol impactor in different particle size ranges. Then, the particle size-cutting efficiency curve is plotted to obtain the cutting particle size.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle, characterized in that, include: The downstream isokinetic sampling module (1), the mass flow control module (2), the upstream control sampling module (3), and the aerosol mixing module (4) are respectively connected to the upstream control sampling module (3) and the downstream isokinetic sampling module (1). The upstream control sampling module (3) and the downstream isokinetic sampling module (1) are respectively connected to the particle size analyzer probe. The downstream isokinetic sampling module (1) is connected to the mass flow control module (2). The downstream isokinetic sampling module (1) includes a particle size calibration device.

2. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 1, characterized in that, The cutting particle size calibration device includes an upper end cover (101), an aerosol cascade impactor (102) is installed between the upper end cover (101) and the sleeve (103), the sleeve (103) is installed on the base (104), an outer sleeve (112) is installed in the middle of the upper surface of the base (104), the outer sleeve is connected to the flow regulating pipe elbow (108), the flow regulating pipe elbow (108) is connected to the flow regulating pipe (109), the lower end of the flow regulating pipe elbow (108) is connected to the isokinetic sampling pipe (106), the isokinetic sampling pipe (106) is connected to the quick-connect connector (107), and the rear end of the flow regulating pipe (109) is provided with a right angle thread and connected to the reducing connector (110).

3. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 2, characterized in that, The lower end of the elbow (108) is provided with a light hole, and a through plate sleeve is welded inside the light hole. The axis of the through plate sleeve coincides with the axis of the central hole of the base (104).

4. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 2, characterized in that, The isokinetic sampling tube (106) includes an inner sleeve (113), and an isokinetic sampling head (105) is installed at the inlet of the inner sleeve (113).

5. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 4, characterized in that, The isokinetic sampling head (105) is a detachable thin-walled sampling head with an inner-outer diameter ratio of less than 1.

1.

6. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 4, characterized in that, The upper inlet face of the outer sleeve (112) is higher than the upper inlet face of the inner sleeve (113).

7. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 2 or 3, characterized in that, Multiple adjustable legs (111) are installed at the bottom of the base (104).

8. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 1, characterized in that, The flow control module (2) includes a pressure transmitter (201) and a mass flow controller (204). A flow limiting ball valve one (202) and a flow limiting ball valve two (205) are installed on the inflow side and outflow side of the mass flow controller (204). The outflow side pipeline of the flow limiting ball valve two (205) is connected to the parallel oil-free vacuum pump one (206) and oil-free vacuum pump two (207). The pipeline between the flow limiting ball valve two (205) and the oil-free vacuum pump one (206) is connected to a branch with a supplementary ball valve (208). The supplementary ball valve (208) is open to the atmosphere. The flow fluctuation caused by the vacuum pump is reduced by adjusting the valve opening. The pressure transmitter (201) is installed on the branch between the flow regulating pipe (109) and the flow limiting ball valve one (202) to monitor the rise and fall of the pressure of the aerosol cascade impactor (102).

9. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 1, characterized in that, The aerosol mixing module (4) includes an aerosol mixing container, which is connected to a stable aerosol generation source.

10. The modular aerosol impactor cutting particle size calibration system based on the isokinetic sampling principle according to claim 1, characterized in that, The pipelines of the upstream control sampling module (3) and the downstream isokinetic sampling module (1) are set up in parallel with the same geometric structure and arrangement.

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