JP7333979B1 - Airborne particle collection method and airborne particle continuous measurement device - Google Patents

Abstract

The present invention provides a method and a measuring device for separating and collecting two types of particles or aerosols having different particle sizes and concentrations contained in the same sample air. [Solution] A method for collecting suspended particles is to classify suspended particles in the air with a virtual impactor 1 into air containing coarse suspended particles with a large particle size and air containing fine suspended particles with a small particle size. The air containing coarse suspended particles is sucked in to collect the coarse suspended particles, while the air containing fine suspended particles is sucked while being bypassed, and the fine suspended particles are collected at a position different from the position where the coarse suspended particles are collected. Collect particles. [Selection diagram] Figure 2

Description

TECHNICAL FIELD The present invention relates to a method for collecting suspended particles in ambient air and indoor air, and a continuous measurement apparatus for suspended particles.

Particles suspended in the ambient air and indoor air can pose serious respiratory hazards. It is In addition, as a measurement method for that purpose, it is recommended to collect sedimentary particles with a large particle size (particle size of 10 μm or more) except for particles.

For this reason, in Japan, the particles collected by removing 100% of particles with a particle size of over 10 μm at 10 μm (100% cut at 10 μm) are called suspended particulate matter (SPM). PM ₁₀ (50% cut at 10 μm) is obtained by removing 50% at 10 μm at 10 μm or more.

In addition, from the results of large-scale epidemiological studies conducted in the United States since the 1980s, it has been reported that particles with a particle size of 2.5 μm or less (50% cut at 2.5 μm) among PM ₁₀ trigger myocardial infarction. , set environmental standards for PM _2.5 worldwide. In Japan, this is called microparticulate matter and standards are established. For this reason, measurement of PM _2.5 is required along with PM ₁₀ and SPM.

On the other hand, occupational safety and health standards also set standards for suspended particulate matter in the air. Particles with a particle size of 4 μm or less (50% cut at 4 μm) are regarded as “inhalable dust” that may reach the alveoli, and are required to be measured together with PM ₁₀ .

In addition, in the medical research field of respiratory diseases (for example, a review is given in Aerosol Science Technology and Applications, 2014), "respirable dust" is defined as "inhalable dust" with a particle size of 5 μm or less, not with a particle size of 4 μm or less. It is said that it is a sexual dust.

In general, particles of 5 μm or less reach deep into the body and are partially deposited, and are considered to have a great impact on health. Among them, particles with a particle size of more than 1 μm and less than 5 μm are often adsorbed in the throat and trachea, and some of them reach the lungs and are adsorbed. On the other hand, particles with a particle size of 1 μm or less exhibit behavior similar to that of oxygen or nitrogen gas, and once reach the lungs, but most of them are exhaled again with exhalation.

In this way, the dispersed phase particles of aerosols (fumes) in the air differ in the manner and components of their deposition in the body depending on their particle size. It is desired to develop a sampling method and apparatus capable of separately collecting the particles and continuously measuring their weight.

Techniques using a virtual impactor are known for classifying particles, as in Patent Documents 1 and 2, for example. These techniques alone are not sufficient to achieve the above objectives, as large volumes of air must be sampled to collect commensurate amounts.

If you try to collect the particles contained in the same sample air separately with different spots, the concentration of particles with a particle size of 1 μm or less is higher, so particles with a particle size of 1 μm or less are collected excessively. There is a problem that suspended particles with a particle size exceeding 1 μm cannot be collected in an amount suitable for the analysis method.

JP 2016-142722 A Japanese Patent Application Laid-Open No. 2019-20372

An object of the present invention is to separately collect coarse suspended particles having a particle size of more than 1 μm and fine suspended particles having a particle size of 1 μm or less contained in the same sample air in separate spots, and to analyze the same. To provide a method for collecting airborne particles and a continuous measuring device for airborne particles, capable of collecting up to an amount corresponding to , and continuously measuring the collected mass of each particle.

The present invention classifies suspended particles in the air with a virtual impactor to separate air containing coarse suspended particles with a large particle size and air containing fine suspended particles with a small particle size,
Air containing coarse suspended particles is sucked and the coarse suspended particles are collected by a filter,
The air containing the fine suspended particles flowing out from the virtual impactor is divided into a flow to the collecting part that collects the fine suspended particles and a bypass flow that bypasses the fine suspended particles without collecting them, and sucked. A method for collecting suspended particles, characterized in that fine suspended particles are collected by a filter at a position different from the position at which coarse suspended particles are collected.

Further, in the present invention, air containing suspended particles is sucked, and the suspended particles in the sucked air are divided into air containing coarse suspended particles with a large particle size and air containing fine suspended particles with a small particle size. a virtual impactor for classification;
a suction means connected to the virtual impactor for sucking a portion of the air containing the fine suspended particles flowing out from the virtual impactor and distributing the air to the fine suspended particle collecting section; bypass means for sucking the remainder of the contained air and bypassing it to the exhaust section as a bypass flow that does not collect fine suspended particles ;
A tape-shaped filter is provided, and air containing coarse suspended particles and air containing fine suspended particles classified by the virtual impactor are sucked through different positions of the tape-shaped filter to separate coarse suspended particles and fine suspended particles. a collecting means for continuously collecting the particles at different positions of the tape-like filter;
detection means for successively detecting suspended particles collected at different positions of the tape-shaped filter by the collection means;
A continuous measurement of airborne particles, characterized by comprising an output of a detection means and an arithmetic recording means for calculating and recording coarse particles in the air and fine airborne particles from the integrated value of the suction air flow rate. It is a device.

According to the present invention, by simultaneously sucking two types of suspended particles having different particle sizes and concentrations in the air, the two types of particles having different required amounts are collected at different positions, and the respective Quantity can be measured efficiently.

According to the present invention, by adjusting the amount of air to be bypassed according to the difference in the particle size and concentration of two types of suspended particles in the air, each amount can be efficiently measured simply by sucking them in simultaneously. Therefore, it has the feature of being highly adaptable as a method for measuring substances in the air.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view schematically showing the configuration of a virtual impactor 1 provided in a floating particle measuring apparatus according to an embodiment of the present invention; FIG. 2 is a system diagram showing the configuration of a floating particle measuring apparatus including the virtual impactor 1 of FIG. 1; 4 is a plan view showing collection positions 3, 3'; 4, 4' of the filter 9. FIG. FIG. 3 is a graph showing an example of the result of continuously measuring the concentration of suspended particles in indoor air for 7 days by the β-ray absorption method using the suspended particle measuring device of the present embodiment shown in FIG. 2 . A classifier 52 that classifies at 5 μm and a virtual impactor 1 that classifies at 1 μm are used in the airborne particle measurement apparatus of this embodiment shown in FIG. It is a graph which shows an example of the result of continuous measurement for days.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, substantially corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.

FIG. 1 is a cross-sectional view showing the configuration of a virtual impactor 1 according to an embodiment of the present invention, and FIG. 2 is a system diagram showing the configuration of an airborne particle measuring apparatus equipped with the virtual impactor 1 of FIG. In the airborne particle collection method of the present embodiment, first, sample air is taken in from a collection port 53, and particles with a particle size of 5 μm or more are removed using a classifier (impactor or cyclone) 52. FIG. The sample air containing suspended particles with a particle size of less than 5 μm is classified by the virtual impactor 1, and coarse suspended particles with a particle size exceeding 1 μm (particle size exceeding 1 μm and less than 5 μm, Coarse Particle; hereinafter sometimes abbreviated as “CP” ) and air containing fine suspended particles with a particle size of 1 μm or less (Fine Particles; hereinafter sometimes abbreviated as “FP”). Particles are collected by the filter 9, and most of the air containing fine suspended particles is sucked by bypassing the filter 9 without being collected at the same position by the bypass means 2, and coarse suspended particles are collected by the filter 9. Including collecting fine airborne particles at a location different from the collection location.

In addition, if the cutting characteristic of the virtual impactor 1 is set to 2.5 μm in particle size and the cutting characteristic of the classifier 52 upstream thereof is set to 10 μm, the coarse suspended particles have a particle size of more than 2.5 μm and less than 10 μm (PM _10-2. As ₅ ), it is also possible to collect fine suspended particles as particles (PM _2.5 ) having a particle size of 2.5 μm or less. Therefore, the grain size of the particles can be changed by manufacturing the classifier 52 with a cutting property range of more than 1 μm and less than 10 μm, and the virtual impactor 1 with a cutting property range of more than 0.1 μm and less than 8 μm. It is possible to collect In the present invention, particles larger than the cutting characteristics of the virtual impactor 1 are described as coarse floating particles, and particles smaller than that are described as fine floating particles.

In the embodiment according to the present invention, the virtual impactor 1 includes a nozzle portion 40, an air collecting portion 41, and an air guiding portion 42. The nozzle portion 40 has a circular ejection port 43 having an inner diameter D0. It has a defined cylindrical portion 44 and a constricted tube portion 45 connected to the cylindrical portion 44 . The air guide portion 42 has a first discharge port 46 with an inner diameter D2 and a second discharge port 47 with an inner diameter D3. be.

The air collecting portion 41 has a truncated conical air collecting pipe portion 48 and a cylindrical straight pipe portion 49 coaxially connected to the air collecting pipe portion 48 . The air collecting pipe portion 48 has an inlet 50 with an inner diameter D1 which is on the same axis as the ejection port 43 and which is spaced apart from the outlet 43 by an interval S in the axial direction. The sample air supplied to the nozzle portion 40 flows into the cylindrical portion 44 while increasing the flow velocity by the constricted tube portion 45, and part of the sample air jetted from the ejection port 43 flows into the air collecting portion 41, The main stream flows into the air guide portion 42 . Part of the sample air that has flowed into the air guide section 42 flows into the channel L2 through the second outlet 47, and the rest flows into the channel L3 through the first outlet 46. As shown in FIG.

FIG. 3 is a plan view showing the collection position of the filter. The virtual impactor 1 sucks air at a constant flow rate, and coarse suspended particles with a particle size of more than 1 μm in the sucked air are classified into fine suspended particles with a particle size of 1 μm or less by the force of inertia. of coarse suspended particles enter the air collecting portion 41 and are collected at the position indicated by the reference numeral 3 of the filter 9 therebelow. On the other hand, the air containing fine suspended particles flows along the streamline, and the fine suspended particles in the air for Q2 out of Q0 enter the collection unit 51 and are located at the position of reference numeral 4 of the filter 9 below. be captured. Fine airborne particles in the remaining Q3 air are discharged through the bypass without being collected by the filter 9 . Q0 is confirmed by the flow calculated from the differential pressure between the pressure G3 in the virtual impactor 1 and the pressure sensor G4 (which measures atmospheric pressure), and Q1 and Q2 are measured by the flow sensors MFM1 and MFM2, respectively. be done.

Taking the dimensions of each part of the virtual impactor 1 and the air flows Q0 to Q3 as an example, D0=φ4 mm, D1=φ5 mm, D2=φ12.7 mm, D3=φ12 mm, S=5 mm, and the air flows Q0 to Q3. When the volume flow rate of air corresponding to is Qv0 to Qv3, Qv0 = 125 L / min, Qv1 = 20 L / min, Qv2 = 15 L / min, Qv3 = 90 L / min, D1 / D0 = 1.25, S / D0 = 1.25 and Qv1/Qv0=0.16.

It is adjusted by the flow rate adjusting valve PV3 and the flow rate adjusting valve PV4 so that the volumetric flow rate is Qv0, the flow rate adjusting valve PV1 is adjusted so that the volumetric flow rate is Qv1, and the volumetric flow rate is adjusted by the flow rate adjusting valve PV2 so that the volumetric flow rate is Qv2. .

The introduced air passes through the nozzle portion 40 and is distributed to the outer tube portion (main flow) and the air collecting portion 41 (secondary flow). In this embodiment, the main flow is guided to the bypass means 2 connected to the outlet of the outer tube portion, and further bypassed by the bypass flow and the flow to the collecting portion 51 for collecting the fine suspended particles. and collect fine suspended particles at a second position of the tape-shaped fluorine-based membrane filter (hereinafter sometimes abbreviated as "filter") 9 .

Normally, in a device using a conventional virtual impactor, if there is no bypass means 2 that does not collect in the filter, the flow rate of the main flow is larger than that of the secondary flow, so even if it is as it is, the fine suspension contained in the main flow Filtration of particles is increased, more than filtration of coarse suspended particles.

As a result, the filter paper in the fine suspended particle collection section becomes clogged before the amount required for checking the components of the coarse suspended particles is filtered, and an appropriate amount cannot be collected at the same time. In particular, when a larger amount of air than usual is introduced in order to collect coarse suspended particles whose concentration in the air is low, there is a problem that the amount of fine suspended particles collected becomes excessive.

According to the simultaneous collection method of the present embodiment, most of the fine suspended particles are not filtered by the bypass flow bypassed by the bypass means 2, and the amount of fine suspended particles to be captured is adjusted to an appropriate amount. be able to.

Further, in this embodiment, the amount of air introduced into the virtual impactor 1 and the amount of the bypass flow are controlled by the respective suction pumps P1, P2, and P3 and the flow rate control valves PV1 to PV4 provided in each flow path. It is possible to finely adjust the collection amount by adjusting using the

In this embodiment, sample air sucked into the apparatus is classified by the virtual impactor 1 into air containing fine suspended particles and air containing coarse suspended particles. From the nozzle part 40, it passes through the air collecting part 41 (secondary flow), is filtered at the first position 3 of the tape-shaped fluorine-based membrane filter 9, and is exhausted to the outside through the flow path L1.

The air containing FP is discharged as the main stream from the virtual impactor 1 and guided to the air guide section 42, and is sucked through the flow path L3 by the suction pump P3 and through the flow path L2 by the suction pump P2 to filter 9. The fine suspended particles are divided into a bypass flow that is bypassed without being collected by the filter 9 and a flow to the collection unit 51 that collects the fine suspended particles in the filter 9 .

The bypass means 2 is connected to the outlet of the outer tube of the virtual impactor 1 and sucks the bypassed air by means of a suction pump P3. , the other end is connected to the suction pump P3 via the flow path L3.

At this time, it is important to balance the bypass flow and the flow to the collection unit 51 so that the FP collection amount becomes a desired value by adjusting the suction amounts of the suction pumps P2 and P3. is. That is, when the amount of FP in the atmosphere is very large, adjusting the suction amount of the suction pump P3 to be larger than that of the suction pump P2 increases the amount of bypassed air containing the FP, thereby The flow to 51 is reduced and the amount of FP collected can be reduced.

The flow to the collection unit 51 for collecting fine suspended particles is sucked by the suction pump P1, filtered by the second position 4 of the tape-shaped fluorine-based membrane filter 9, and passed through the flow path L2 to the outside. exhausted.

The bypass flow is sucked by the suction pump P3 and exhausted to the outside through the bypass means 2 and the flow path L3.

In this device, for the air flow Q1, the suction amount of the suction pump P1 is measured using the flow sensor MFM1, and the air flows through the flow channel L1 using the flow control valve PV1 and the pressure sensor G1 provided in the flow channel L1. By adjusting the amount of air, the amount of CP collected at the first position 3 of the filter 9 can be the desired amount collected per unit of time desired.

At the same time, for the air flow Q2, the suction amount of the suction pump P2 is measured using the flow sensor MFM2, and the flow control valve PV2 provided in the flow path L2 and the pressure sensor G2 are used to measure the amount of air passing through the flow path L2. By adjusting the amount, the amount of FP collected at the second position 4 of the filter 9 can be the desired amount collected per desired unit of time. Further, for the air flow Q0, the differential pressure is calculated using pressure sensors G3 and G4, Q0 is obtained from the characteristics of the virtual impactor 1, and Q3 (Q3=Q0-Q1-Q2) is calculated. Q3 adjusts the flow rate of the bypass flow passing through the flow path L3 using the flow rate adjustment valves PV3 and PV4 provided in the flow path L3 to adjust the suction amount of the suction pump P3.

For example, if the sample air Q0 is introduced into the virtual impactor 1 at a flow rate of 125 L (liters) per minute, the secondary flow of air Q1 containing CP from the virtual impactor 1 is 20 L per minute, and the virtual impactor 1 Of the main stream containing the FP from the inlet, the bypass flow Q3 is 90 L/min, and the flow Q2 to the collecting section 51 for collecting the FP is 15 L/min.

As air is continuously passed through the first and second positions 3, 4 of the filter 9, the amount of airborne particles collected on the first and second positions 3, 4 gradually increases and the particles Since the filter 9 is clogged and suction is not possible, the tape feeding mechanism 7 moves the filter 9 by a certain length C in the direction of the arrow 8 at regular intervals or when the amount of FP and CP collected exceeds a certain amount. to start the next collection.

The filter 9 is tape-shaped and is supplied in a state wound around a supply roll 6, is supplied to the first position 3 and the second position 4 by a plurality of guide rollers (not shown), and is supplied to a plurality of guide rollers (not shown) and The tape is taken up by a take-up roller 5 via a tape feeding mechanism 7 consisting of two upper and lower rollers. The tape feeding mechanism 7 feeds the filter 9 by a fixed length C in the direction of the arrow 8 when a fixed time has passed or when the collected amount of FP and CP exceeds a certain fixed amount. This moves the position 3' of the filter 9 to the new position 3 and the position 4' to the new position 4.

Thus, CP and FP collected at the first and second positions 3 and 4 of the filter 9 can be measured by combining known measuring means such as the β-ray absorption method and the light reflection method. can do.

An example of measuring the collected CP and FP by combining the β-ray absorption method and the light reflection method will be described.

The first position 3 and the second position 4 of the filter 9 are irradiated with β-rays from a first β-ray source 10 and a second β-ray source 11, and the amount of transmitted β-rays is continuously detected by a first β-ray detector 12, respectively. , are detected by the second β-ray detector 13 . The detection result is input to a central processing unit (CPU) 28 through the first preamplifier 21 and the second preamplifier 22 .

The first position 3 of the filter 9 is irradiated with white light of constant intensity from a light source 24 via an optical fiber 25, and the reflected light is guided to a photodetector 23 via an optical fiber 26. It is continuously detected by the photodetector 23 every minute, and the detection result is input to the arithmetic processing section 28 via the third preamplifier 27 .

As air is continuously passed through the first and second positions 3, 4 of the filter 9, the amount of airborne particles collected on the first position 3 and the second position 4 gradually increases, Since the first position 3 and the second position 4 are clogged and the suction force is reduced, the tape feeding mechanism 7 moves the filter 9 in the direction of the arrow 8 by a predetermined length C at regular intervals, for example, every hour. is sent and the next measurement is started.

The areas of the first position 3 and the second position 4 for collecting airborne particles of the filter 9 are, for example, circular with a diameter of 11 mm.

The filter 9 is tape-shaped and is unwound from a supply roll 6, and supplied to a first position 3 and a second position 4 by a plurality of guide rollers (not shown). Then, the tape is taken up by a take-up roller 5 via a tape feeding mechanism 7 consisting of two upper and lower rollers. The tape feeding mechanism 7 is configured to feed the filter 9 by a fixed length C in the arrow 8 direction when a fixed time has passed or when the collected amount of FP and CP exceeds a certain fixed amount. This moves the position 3 of the new filter 9 to a new position 3' and the position 4 to a new position 4'.

The relationship between the detection results of the first and second β-ray detectors and the photodetector and the amount of suspended particles on the filter 9 is calculated by Equation (1).

I _j =I _j-1 exp(−μ _m χ _m ) (1)

Here, I _j is the amount of β-rays transmitted through the filter that collected the suspended particles or the amount of light reflected by the filter 9 at a given moment, and I _j-1 is the same amount one minute before. Also, _I0 is the amount of β-rays transmitted through the new filter before collecting suspended particles or the amount of light reflected by the new filter, _μm is the proportionality constant, and _χm is the amount of light captured per unit area of the filter 9. Mass of suspended particles (μg/cm ² ). _μm is a value specific to the β-ray sources 10, 11 and the light source, and is determined in advance in units of cm ² /μg by standard materials. By transforming equation (1), equation (2) is obtained.

χ _m =−1/μ _m ln(I _j /I _j−1 ) (2)

By finding the ratio of I _j and I _j−1 from equation (2), the amount of airborne particles collected per unit area of filter 9 in one minute, for example, can be calculated, which is given by the first position 3 (which is equal to the area of the second location 4, which for a diameter of 11 mm gives approximately 0.95 cm ² ), the mass of airborne particles collected one minute ago (μg/min) can be calculated.

Mass of particles collected by filter 3 from Q1: M (Q1) μg,
Mass of particles collected by filter 4 from Q2: M(Q2) μg.
Here, the mass concentration of sample air is
Mass concentration of CP: [CP] μg/m ³ ,
Mass concentration of FP: [FP] μg/m ³ ,
Also, the integrated flow rate corresponding to Q0 to Q3 when collecting for a certain period of time is described as Q _t0 to Q _t3 (m ³ ).

Here, as a characteristic of the virtual impactor 1,
1. All CPs pass through only Q1 (coarse particle side) of the virtual impactor 1 and are collected by the filter 9 .
2. The FP passes through both Q2 (fine particle side) and Q1 (coarse particle side) of the virtual impactor 1, and the mass (number) of particles collected by the filter 9 corresponds to the split flow ratio of the flow rate.

M(Q2)=[FP]× _Qt2 (3)
M(Q1)=[CP]* _Qt0 +[FP]* _Qt1 (4)

From equations (3) and (4), the mass concentration is

[FP]=M(Q2)/( _Qt2 ) (5)
[CP]={M(Q1)−M(Q2)×(Q _t1 /Q _t2 )}/Q _t0 (6)
is represented by

FIG. 4 shows the concentration of suspended particles in indoor air by the β-ray absorption method using the classifier 52 that classifies at 5 μm and the virtual impactor 1 that classifies at 1 μm in the airborne particle measurement apparatus of the present embodiment shown in FIG. 5 is a graph showing an example of the results of continuous measurement for 7 days, and FIG. 5 shows a classifier 52 that classifies at 5 μm and a virtual impactor 1 that classifies at 1 μm in the airborne particle measuring device of the present embodiment shown in FIG. It is a graph showing an example of the results of continuous measurement of the amount of suspended particles trapped in indoor air for seven days using the β-ray absorption method. In FIG. 4, the vertical axis indicates airborne particle concentration (μg/m ³ ) and the horizontal axis indicates time (days). In FIG. 5, the vertical axis indicates the trapped airborne particle amount (μg) per hour, and the horizontal axis indicates the time (day). From FIG. 4, it can be seen that the concentration of coarse suspended particles (with a particle size of more than 1 μm and less than 5 μm) in indoor air is about 1 to 3 μg/m ³ , which is low. On the other hand, as shown in FIG. 5, it can be seen that the amount of large suspended particles (particle size exceeding 1 μm and less than 5 μm) collected per hour was as large as 10 to 20 μg.

Furthermore, looking at the 10 hours from 1:00 AM to 11:00 AM on April 20, 2022, the average concentration of coarse suspended particles during this period was 2.1 μg / m ³ , while fine suspended particles 18 0 μg/m ³ . In addition, the tape was moved as a filter once an hour, and the average collection amount during this period was 16.0 μg of coarse suspended particles and 16.1 μg of fine suspended particles. If the same air during this period is sampled at a volume of approximately 1 m ³ per hour by moving the tape once an hour with an apparatus using a conventional virtual impactor without using the present invention, The average collection amount of coarse suspended particles is only 2.1 μg. In the conventional method, if the tape is moved once every 10 hours, for example, and the collection time is lengthened to collect coarse suspended particles, not only does the time resolution deteriorate, but the accumulated amount of collected coarse suspended particles increases. 21 μg and 180 μg of fine suspended particles, which is a sufficient amount of coarse suspended particles to be collected, but the amount of fine suspended particles collected becomes excessive, and the filter may clog with particles and become unable to be collected. is expected. In the conventional method, when 80 to 100 μg of airborne particles are collected in the filter, clogging occurs and collection becomes impossible. In addition, if the detection limit of the β-ray absorption method is expressed as a filter collection amount, for example, it is 1 to 2 μg, and the average concentration of coarse suspended particles is 2.1 μg / m ³ , so once an hour as in the conventional method If the tape movement is 2.1 μg, the average collected amount will be 2.1 μg, and the measurement will have a large error in the vicinity of the detection limit during this period. On the other hand, in the present invention, since the average filter collection amount was 16.0 μg, accurate measurement was possible.

Thus, the effect of the present invention is that even if the concentration of coarse particles in the sample air is low, it can be efficiently concentrated, the amount of particles trapped in the filter can be increased, and high sensitivity can be achieved. I know I can measure it.

1 Virtual Impactor 2 Bypass Means 3 First Position for Collecting Floating Particles 4 Second Position for Collecting Floating Particles 5 Tape Take-up Roller 6 Tape Supply Roll 7 Tape Feeding Mechanism 8 Arrow 9 Tape Membrane Filter 10 First β-ray source 11 Second β-ray source 12 First β-ray detector 13 Second β-ray detector 14 Flow of β-rays 21 First preamplifier 22 Second preamplifier 23 Photodetector 24 Light source 26 Optical fiber 27 Third preamplifier 28 Arithmetic processing Part 40 Nozzle Part 41 Air Collecting Part 42 Air Guide Part 43 Jet Port 44 Cylindrical Part 45 Constricted Pipe Part 46 First Discharge Port 47 Second Discharge Port 48 Air Collecting Pipe Portion 49 Straight Pipe Portion 50 Inflow Hole 51 Collecting Portion 52 Classifier 53 sampling port G1 pressure sensor G2 pressure sensor G3 pressure sensor G4 pressure sensor L1 channel L2 channel L3 channel P1 suction pump P2 suction pump P3 suction pump MFM1 flow sensor MFM2 flow sensor PV1 flow control valve PV2 flow control valve PV3 flow control Valve PV4 flow control valve

Claims (2)

Classifying suspended particles in the air with a virtual impactor to separate the air containing coarse suspended particles with a large particle size from the air containing fine suspended particles with a small particle size,
Air containing coarse suspended particles is sucked and the coarse suspended particles are collected by a filter,
The air containing the fine suspended particles flowing out from the virtual impactor is divided into a flow to the collecting part that collects the fine suspended particles and a bypass flow that bypasses the fine suspended particles without collecting them, and sucked. A method for collecting suspended particles, characterized in that fine suspended particles are collected by a filter at a position different from a position where coarse suspended particles are collected. a virtual impactor that sucks air containing suspended particles and classifies the sucked suspended particles into air containing coarse suspended particles with a large particle size and air containing fine suspended particles with a small particle size;
a suction means connected to the virtual impactor for sucking a portion of the air containing the fine suspended particles flowing out from the virtual impactor and distributing the air to the fine suspended particle collecting section; bypass means for sucking the remainder of the contained air and bypassing it to the exhaust section as a bypass flow that does not collect fine suspended particles ;
A tape-shaped filter is provided, and air containing coarse suspended particles and air containing fine suspended particles classified by the virtual impactor are sucked through different positions of the tape-shaped filter to separate coarse suspended particles and fine suspended particles. a collecting means for continuously collecting the particles at different positions of the tape-like filter;
detection means for successively detecting suspended particles collected at different positions of the tape-shaped filter by the collection means;
A continuous measurement of airborne particles, characterized by comprising an output of a detection means and an arithmetic recording means for calculating and recording coarse particles in the air and fine airborne particles from the integrated value of the suction air flow rate. Device.