NL2007089C2

NL2007089C2 - Air sampling apparatus.

Info

Publication number: NL2007089C2
Application number: NL2007089A
Authority: NL
Inventors: Takuo Hirakawa
Original assignee: Kobe Steel Ltd
Priority date: 2010-07-21
Filing date: 2011-07-12
Publication date: 2012-12-18
Also published as: KR20120000963U; CN202255983U; KR200467050Y1; JP3163165U; NL2007089A

Description

AIR SAMPLING APPARATUS

BACKGROUND OF THE INVENTION

1. Field of the Invention 5 The present invention relates to an air sampling apparatus which collects particles in the air to determine the proportion of the particles in the air.

2. Description of the Related Art

Examples of sampling methods for collecting particles 10 (for example, salt particles) to determine the proportion of the particles in the air include a dry gauze method and a wet gauze method (see, for example, Technical note of Port and Harbour Research Institute, Ministry of Transportation, Japan, No. 784, pp. 6-8, September 1994 (hereinafter 15 referred to as Non-Patent Document 1)). Figs. 6A and 6B are schematic diagrams illustrating a known particle sampling method. Referring to Fig. 6A, in the dry gauze method, gauze 7 is attached to a frame member 6 having a 10-cm-square hole, and particles that adhere to the gauze 7 are 20 sampled. Referring to Fig. 6B, in the wet gauze method, gauze 7 is wrapped around a columnar member so as to form a cylindrical shape having a diameter of 2.5 cm and a length of 12 cm. Moisture is supplied to the gauze 7 so that the gauze 7 is constantly wet. In this state, particles that 25 adhere to the gauze 7 are sampled.

2007089" 2

In the above-described particle sampling methods disclosed in Non-Patent Document 1, the gauze 7, which serves as a sampling member, is exposed. Therefore, the sampling process is easily influenced by, for example, wind 5 and rain. When, for example, the proportion or the like of the particles in a unit volume of air is measured, the accuracy of the measurement result is reduced.

To solve this problem, various air sampling apparatuses have been proposed in which a particle sampling member (for 10 example, gauze, a filter, etc.) is disposed in a frame body. Japanese Unexamined Patent Application Publication No. 2009-198224 (hereinafter referred to as Patent Document 1) discloses an air sampling apparatus in which outside air is introduced into a chamber through a sampling pipe and 15 particles in the introduced air are captured with a filter disposed at a side of the chamber.

Japanese Unexamined Patent Application Publication No. 11-183335 (hereinafter referred to as Patent Document 2) discloses an air sampling apparatus into which air is 20 introduced and in which moisture is supplied to the introduced air with a sprayer to form a mist. The particles in the air are captured by collecting the mist into liquid. Japanese Unexamined Patent Application Publication No. 2009-175063 (hereinafter referred to as Patent Document 3) 25 discloses an air sampling apparatus in which inorganic 3 impurities in the air are ionized by an electric discharge from a discharge electrode and are collected into liquid.

Japanese Unexamined Patent Application Publication No. 2009-128054 (hereinafter referred to as Patent Document 4) 5 discloses an air sampling apparatus into which air is introduced through, for example, a resin tube connected to an air pump. Japanese Unexamined Patent Application Publication No. 2010-124711 (hereinafter referred to as Patent Document 5) discloses a technique for sucking air 10 into an apparatus by using a fan installed in the apparatus.

However, as described above, the technique disclosed in Non-Patent Document 1 has a problem that since the gauze 7, which serves as a sampling member, is exposed, the sampling process is easily influenced by, for example, wind and rain 15 and the particles in the air cannot be easily sampled.

Therefore, the measurement accuracy of the content or the like of the particles is reduced. In addition, the technique of Non-Patent Document 1 uses an exposure-type sampling method. Therefore, an extremely long sampling time 20 is required when a relatively large amount of particles is to be sampled, and there is a problem that the sampling efficiency is low. In particular, with the exposure-type sampling method, when, for example, the particles are sampled in an outdoor location, the sampled particles will 25 be washed away if it rains. In such a case, the measurement 4 must be performed again, which greatly reduces the sampling efficiency.

In the techniques described in Patent Documents 1 to 5, the outside of the apparatus and the inside of the apparatus 5 are connected to each other with a pipe or a tube having a constant inner diameter. Therefore, if the diameter is large, the measurement accuracy of the particles is reduced because of the airflow from outside of the apparatus. In contrast, if the inner diameter of the pipe or the tube is 10 small, the area through which the outside air is introduced is small, which may lead to variations in measurement results. In particular, the technique of Patent Document 4, in which the air is introduced through a resin tube, has a problem that the tube is easily deformed, which leads to a 15 reduction in the measurement accuracy.

In addition, with the techniques according to Patent Documents 2 to 4, the sprayer, the discharge electrode, a suction control device, etc., must be installed in the apparatus. Therefore, the structure of the apparatus is 20 complex and the manufacturing cost is increased.

SUMMARY OF THE INVENTION

in light of the above-described problems, an object of the present invention is to provide an air sampling 25 apparatus which has a simple structure and with which the 5 proportion of particles in the air can be accurately determined by using sampled air.

According to an aspect of the present invention, an air sampling apparatus includes a sampling box into which air to 5 be analyzed is introduced; a reducer pipe provided on the sampling box and having an air inlet at a distal end, the air inlet having a diameter smaller than a diameter of the reducer pipe at a proximal end that is adjacent to the sampling box and wherein the diameter of the reducer pipe 10 gradually increases from the distal end to the proximal end, the air being introduced into the reducer pipe and guided into the sampling box from the proximal end of the reducer pipe; a fan that sucks the air into the sampling box; a filter provided in an air channel including the reducer pipe 15 and the sampling box, the filter blocking predetermined particles in the air introduced from the reducer pipe; and a sensor that measures the amount of the air that flows through the air channel. A proportion of the particles in the air is determined from the amount of the air and the 20 amount of the particles that adhere to the filter.

According to the present invention, a mesh size of the filter may be in the range of 1 |Jm to 3 Jim.

The air sampling apparatus may further include, for example, a pair of clamping members having holes, the filter 25 being clamped between portions of the clamping members 6 around the holes. In this case, the clamping members are disposed in, for example, the sampling box and the sampling box is provided with a lid that is capable of being opened and closed to allow the filter to be replaced.

5 The air sampling apparatus may further include, for example, a second reducer pipe attached to the sampling box. The fan is connected to the sampling box with the second reducer pipe provided therebetween. Here, an inner diameter of the second reducer pipe at an end adjacent to the fan is 10 larger than an inner diameter of the second reducer pipe at an end adjacent to the sampling box. The sensor is preferably provided in, for example, the reducer pipe or the second reducer pipe.

In the above-described air sampling apparatus, the 15 sampling box is made of, for example, a transparent or translucent material, and the state of the filter can be observed from outside the sampling box.

According to the air sampling apparatus of the present invention, the reducer pipe is provided on the sampling box, 20 and the air to be analyzed is introduced into the sampling box through the reducer pipe. The diameter of the air inlet at the distal end of the reducer pipe is smaller than the diameter of the reducer pipe at the proximal end. Accordingly, the introduced air can be rectified in the area 25 of the reducer pipe whose diameter gradually increases.

7

Accordingly, reduction in the measurement accuracy of the proportion of the particles in the air due to wind and the like from the outside can be prevented.

In addition, the filter that blocks the particles in 5 the air is provided in the air channel including the reducer pipe and the sampling box. The proportion of the particles in the air can be accurately determined from the amount of the air measured by the sensor and the amount of the particles that adhere to the filter.

10 The air sampling apparatus according to the present invention has a simple structure in which the reducer pipe is attached to the sampling box and the filter, the fan, and the sensor are installed in the air sampling apparatus. Therefore, increase in the manufacturing cost of the air 15 sampling apparatus can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side view of an air sampling apparatus according to an embodiment of the present invention; 20 Fig. 2 is a perspective view of an air sampling unit;

Fig. 3A is a front view of a fan;

Fig. 3B is a side view of a fan;

Fig. 4 is a side view of a modification of the air sampling apparatus according to the embodiment of the 25 present invention;

Fig. 5 is a graph illustrating examples of performance curves of a fan,- 8

Fig. 6A is a diagram illustrating a dry gauze method; and 5 Fig. 6B is a diagram illustrating a wet gauze method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described in detail with reference to the accompanying 10 drawings. First, the structure of an air sampling apparatus 1 according to the present embodiment will be described.

Fig. 1 is a side view of the air sampling apparatus 1 according to the embodiment of the present invention. Fig.

2 is a perspective view of an air sampling unit 2. Figs. 3A 15 and 3B are a front view and a side view, respectively, of a fan 3. As illustrated in Fig. 1, the air sampling apparatus 1 according to the present embodiment includes the air sampling unit 2 for sampling the air to be analyzed and the fan 3 for sucking the air.

20 As illustrated in Fig. 2, the air sampling unit 2 includes a box-shaped sampling box 2d into which the air to be analyzed is introduced. A first reducer pipe 2a and a second reducer pipe 2e are fixed to side surfaces of the sampling box 2d that face each other. The air is introduced 25 into the sampling box 2d through the first reducer pipe 2a, 9 is guided to the fan 3 through the second reducer pipe 2e, and is then discharged to the outside. A filter 2c is disposed in an air channel including the first reducer pipe 2a and the sampling box 2d. The air introduced through the 5 reducer pipe 2a is caused to pass through the filter 2c so that a certain component in the air, such as particles of salt or the like in the air, is captured by the filter 2c.

In the present embodiment, a pair of filter attachment plates 2b are disposed in the sampling box 2d, and the 10 filter 2c is clamped between the filter attachment plates 2b.

The first reducer pipe 2a is arranged such that the inner diameter thereof at an air inlet side is smaller than the inner diameter thereof at the side adjacent to the sampling box 2d. Accordingly, the air introduced into the 15 pipe can be rectified in the pipe whose diameter gradually increases, so that the influence of, for example, wind that enters the reducer pipe 2a from the outside can be reduced.

In the present embodiment, the second reducer pipe 2e is also formed such that the inner diameter thereof at the side 20 adjacent to the fan 3 is larger than the inner diameter thereof at the side adjacent to the sampling box 2d. Accordingly, the introduced air can be rectified not only in the first reducer pipe 2a but also in the second reducer pipe 2e. The inner diameter of the first reducer pipe 2a at 25 the air inlet side is in the range of, for example, 50 mm to 10 100 mm, and the inner diameter thereof at the side adjacent to the sampling box 2d is in the range of, for example, 100 mm to 150 mm. The inner diameter of the second reducer pipe 2e at the side adjacent to the fan 3 is in the range of, for 5 example, 100 mm to 150 mm, and the inner diameter thereof at the side adjacent to the sampling box 2d is in the range of, for example, 175 mm to 210 mm.

In the present embodiment, sensors, for example, a first pressure sensor 4 and a second pressure sensor 5, for 10 measuring the amount of the air that has been introduced are disposed in the first reducer pipe 2a. The first pressure sensor 4 is located on, for example, a pipe axis of the reducer pipe 2a at a position near holes, which will be described below, formed in the filter attachment plates 2b 15 to allow the air to pass therethrough. The first pressure sensor 4 is disposed coaxially with the holes. Thus, the pressure of the air introduced into the air sampling apparatus 1 can be measured by the first pressure sensor 4. The second pressure sensor 5 is disposed on, for example, an 20 inner wall of the reducer pipe 2a at the periphery thereof in the radial direction at a position corresponding to the first pressure sensor 4. Thus, the static pressure of the air introduced into the air sampling apparatus 1 can be measured by the second pressure sensor 5. The amount of air 25 that is introduced through the reducer pipe 2a and flows 11 through the air channel can be determined from, for example, a pressure difference (dynamic pressure) between the pressure measurement value obtained by the first pressure sensor 4 and the measurement value of the static pressure 5 obtained by the second pressure sensor 5, the specific gravity and temperature of the air, and the area of the air channel at a position where the first and second pressure sensors 4 and 5 are positioned. The measurement values obtained by the first and second pressure sensors 4 and 5 10 are displayed on, for example, a display device 8 disposed outside the reducer pipe 2a.

The sampling box 2d is formed of, for example, plateshaped members, such as transparent or translucent acrylic plates, and has a cubic shape with an edge length of, for 15 example, 250 mm. The thickness of the plates is, for example, 15 mm. When the sampling box 2d is transparent or translucent, the inside of the sampling box 2d can be observed from the outside. A hole through which the air is introduced is formed in a side surface of the sampling box 20 2d. This hole has, for example, a circular shape with a~ diameter that is smaller than or equivalent to, for example, the inner diameter of the reducer pipe 2a. The first reducer pipe 2a is fixed to the sampling box 2d at a position corresponding to the position of this hole. In 25 addition, a hole through which the air is discharged toward 12 the fan 3 is formed in a side surface of the sampling box 2d that is opposed to the side surface on which the first reducer pipe 2a is provided. This hole has, for example, a circular shape with a diameter that is slightly smaller than 5 or equivalent to the inner diameter of the second reducer pipe 2e. The second reducer pipe 2e is fixed to the sampling box 2d at a position corresponding to the position of this hole.

One of the filter attachment plates 2b is fixed, for 10 example, with bolts to an inner surface of the sampling box 2d at, for example, the side at which the reducer pipe 2a is disposed. The filter 2c is placed on the filter attachment plate 2b that is fixed. Then, the other filter attachment plate 2b is placed on the filter 2c, and is fixed thereto 15 with, for example, bolts. Thus, the filter 2c is attached to the filter attachment plates 2b such that it is clamped between the filter attachment plates 2b. The pair of filter attachment plates 2b have holes having, for example, a circular shape with a size that is smaller than or 20 equivalent to, for example, the size of the air introduction hole in the side surface of the sampling box 2d. Thus, the filter 2c is clamped between portions of the filter attachment plates 2b around the holes. When the air introduced into the air channel passes through the holes, 25 particles larger than the mesh size of the filter 2c adhere 13 to the filter 2c, so that the particles can be collected.

The holes have, for example, a circular shape with a diameter in the range of 50 mm to 150 mm (for example, 100 mm). To provide the overlap area between the filter 3 and 5 the filter attachment plates 2b when the filter 3 is attached, the size of the filter 3 is preferably larger than the size of the holes in the filter attachment plates 2b by, for example, 20 mm or more (for example, the filter 3 may have a circular shape with a diameter of 120 mm). When a 10 portion of the filter 2c to which the particles adhere has a circular shape, the particles uniformly adhere to the filter surface. Assuming that the amount of the air that passes through a unit area of the filter 2c is constant, if the diameter of the portion of the filter 2c to which the 15 particles adhere is less than 50 mm, the amount of the air that passes through the entire area of the filter 2c per unit time decreases. As a result, the sampling time increases. If the diameter is greater than 150 mm, the pressing force applied by the air that passes through the 20 entire area of the filter 2c increases, and the filter 2c easily breaks. The size of the portion of the filter 2c to which the particles adhere (size of the holes in the filter attachment plates 2b) can be selected as appropriate in accordance with, for example, the kind of the fan 3, which 25 will be described below. More specifically, when, for 14 example, a plurality of kinds of filter attachment plates 2b having holes with different sizes are prepared in advance, the area of the portion to which the particles adhere can be changed by changing the size of the holes. The top surface 5 of the sampling box 2d is defined by, for example, a lid of the sampling box 2d. The lid is closed during an air sampling process, and is opened after the sampling process so that the filter 2c can be collected or replaced.

The size of the mesh of the filter 2c is, for example, 10 in the range of 1 |Jm to 3 pm, and is set to, for example, 3 pm. In general, the mesh width of the gauze 7 used in the dry gauze method and the wet gauze method illustrated in Figs. 6A and 6B is 700 pm. Therefore, sea salt particles, for example, whose particle diameter is 250 pm, easily pass 15 through the mesh of the gauze 7. Therefore, even when a plurality of sheets of gauze 7 are stacked, the capturing rate of the sea salt particles is reduced, which leads to a reduction in the accuracy of the measurement values. In contrast, in the present embodiment, a filter having a small 20 mesh width used to capture fumes in a welding process, for example, is used as the filter. Thus, the capturing rate of the particles in the air can be increased. As a result, the measurement accuracy can be increased and the analysis of the particles can be accurately performed.

25 The second reducer pipe 2e is provided with a flange 15 portion 2f that projects outward at the end opposite to the end adjacent to the sampling box 2d. The fan 3 is fixed to the flange portion 2f with, for example, bolts.

Referring to Figs. 3A and 3B, a centrifugal blower, for 5 example, which sucks in air and discharges the air in the radial direction may be used as the fan 3. Instead of the centrifugal blower, an axial blower which discharges the sucked air in an axial direction or a mixed flow blower which discharges the sucked air in an oblique direction may 10 be used as the fan 3. Thus, in the present invention, the fan 3 is selected as appropriate in accordance with the amount of the air to be sampled in a time unit, the kind of the filter 2c, and other factors. For example, when the suction air flow rate is to be increased, a high-pressure 15 blower fan may be used. When the size and weight of the fan itself are to be reduced, a propeller fan, a sirocco fan, or a combination thereof may be used. In the present embodiment, a centrifugal blower is used as the fan 3. The fan 3 includes a fan unit 3a, a driving unit 3b, a power 20 source unit 3c, and an outlet 3d. A fan member disposed in a casing of the fan unit 3a is rotated by, for example, a motor included in the driving unit 3b. Accordingly, the air is sucked in an axial direction of the fan member and is discharged from the outlet 3d. The motor included in the 25 driving unit 3b is driven by, for example, electric power supplied to the power source unit 3c from an external power source through a power cord 3e.

16

Next, an operation of the air sampling apparatus according to the present embodiment will be described.

5 First, the lid at the top of the sampling box 2d is opened and the filter 2c is attached to the filter attachment plates 2b. More specifically, the filter 2c is placed on one of the filter attachment plates 2b that is fixed to the back surface of the side wall on which the reducer pipe 2a 10 is provided, such that the position of the filter 2c with respect to the hole in the filter attachment plate 2b is adjusted. Then, the other filter attachment plate 2b is placed on the filter 2c and fixed thereto with, for example, bolts. Thus, the filter 2c is attached to the filter 15 attachment plates 2b such that it is clamped between the filter attachment plates 2b. After the filter 2c is attached, the lid of the sampling box 2d is closed.

Next, the power cord 3e is connected to the external power source so that the state in which electric power can 20 be supplied to the power source unit 3c is established.

Then, the fan 3 is switched on. Thus, the electric power is supplied to, for example, the motor in the driving unit 3b from the power source unit 3c so as to rotate the motor. Accordingly, the fan member in the fan unit 3a is rotated.

25 As a result, the air around the fan 3 is sucked into the fan 17 unit 3a, and flows outward, while swirling, in the radial direction of the fan 3 while receiving kinetic energy from the fan 3. Then, the air is discharged from the outlet 3d. Accordingly, the pressure at the suction side of the fan 3 5 is temporarily set to a negative pressure. As a result, the air in front of the fan 3 successively flows toward the inlet of the fan 3. In this manner, the air sampling apparatus 1 starts to take in the air.

First, the air around the first reducer pipe 2a is 10 sucked into the reducer pipe 2a through the inlet thereof.

The air introduced into the reducer pipe 2a flows, for example, in the axial direction of the reducer pipe 2a. In the present invention, the reducer pipe 2a is arranged such that the inner diameter thereof at the side of the sampling 15 box 2d is larger than the inner diameter thereof at an air inlet side. Therefore, even when the flow of air that is introduced into the pipe is disturbed because of, for example, wind and rain outside the apparatus, the air can be rectified as the air flows through the pipe whose diameter 20 gradually increases. In this way, reduction in the analysis accuracy due to wind and the like from the outside can be prevented.

The air that flows through the reducer pipe 2a reaches the position where the first pressure sensor 4 is disposed.

25 Since the air that flows through the pipe has kinetic energy, 18 the first pressure sensor 4 measures the sum of the static pressure and the dynamic pressure of the air that corresponds to the kinetic energy thereof. The measurement value of the first pressure sensor 4 is displayed on the 5 display device 8. The second pressure sensor 5 is disposed on the inner wall of the reducer pipe 2a at the periphery thereof in the radial direction at a position corresponding to the first pressure sensor 4. The second pressure sensor 5 measures the static pressure of the air at the same 10 position as the position of the first pressure sensor 4 in the axial direction. The measurement value of the second pressure sensor 5 is displayed on the display device 8. Accordingly, the amount of the air that is introduced through the reducer pipe 2a can be extremely accurately 15 determined from a pressure difference (dynamic pressure) between the measurement value obtained by the first pressure sensor 4 and the measurement value of the static pressure obtained by the second pressure sensor 5, the specific gravity and temperature of the air, and the area of the air 20 channel at a position where the first and second pressure sensors 4 and 5 are positioned.

The air flows through the first reducer pipe 2a in, for example, a pipe axis direction, and passes through the air inlet hole in the sampling box 2d, the holes in the filter 25 attachment plates 2b, and the filter 2c. At this time, 19 particles in the air are filtered by the filter 2c. More specifically, particles larger than the mesh width of the filter 2c do not pass through the filter 2c. The particles that do not pass through the filter 2c adhere, for example, 5 to the filter 2c. In the present embodiment, the mesh width of the filter 2c is smaller than that of the gauze that is generally used in the dry gauze method and the wet gauze method. Therefore, even when, for example, the sea salt particles whose particle diameter is 250 |Jm try to pass 10 through the filter 2c, the particles cannot pass through the filter 2c and adhere to, for example, the filter 2c since the size thereof is larger than the mesh width of the filter 2c. Thus, in the present embodiment, the capturing rate of particles with small diameters can be increased. As a 15 result, the measurement accuracy can be increased and the particles can be accurately analyzed.

The air that has passed through the filter 2c enters the sampling box 2d and flows through the sampling box 2d.

In the case where the sampling box 2d is formed of a 20 transparent or translucent material, the state of the filter 2c can be observed from outside the sampling box 2d. For example, whether or not the filter 2c is clogged, damaged, etc., can be observed from outside the sampling box 2d.

When, for example, the filter 2c is damaged, the filter 2c 25 can be replaced by opening the lid at the top of the 20 sampling box 2d, and it is not necessary to wait for the particle sampling process using the damaged filter 2c to be finished. Thus, reduction in the sampling efficiency can be suppressed.

5 The air that has flowed through the sampling box 2d enters the second reducer pipe 2e and flows toward the fan 3. Similar to the first reducer pipe 2a, the second reducer pipe 2e is also formed such that the inner diameter thereof at the outlet side is larger than the inner diameter thereof 10 at the inlet side. Accordingly, an additional rectifying effect can be obtained in addition to the rectifying effect provided by the first reducer pipe 2a.

The air that has flowed through the second reducer pipe 2e is sucked into the fan 3. Then, as described above, the 15 air flows outward, while swirling, in the radial direction of the fan 3 while receiving kinetic energy from the fan 3. Then, the air is discharged from the outlet 3d.

The above-described air sampling operation is continued for a certain time period, and is ended by stopping the 20 motor in the driving unit 3b. Then, the lid at the top of the sampling box 2d is opened and the filter 2c having the particles adhering thereon is taken out.

The proportion of the particles in the air at a certain location can be determined from the amount of the particles 25 adhering to the filter 2c that has been taken out and the 21 amount of the air measured by the sensors. More specifically, the total amount of particles in the air that have flowed through the air channel can be determined from the difference between the weight of the filter 2c before 5 the measurement and that after the measurement. The proportion of the particles in the air can be determined by dividing the determined value by the amount of the air. For example, proportions of specific kinds of particles, such as salt particles, included in the particles adhering to the 10 filter 2c can also be determined individually for each kind of particles.

As described above, the air sampling apparatus 1 according to the present embodiment has a simple structure in which the reducer pipes 2a and 2e are attached to the 15 sampling box 2d and the filter 2c, the fan 3, and the sensors 4 and 5 are installed in the air sampling apparatus 1. Therefore, increase in the manufacturing cost of the air sampling apparatus 1 can be suppressed.

In addition, in the present embodiment, the reducer 20 pipe 2a through which the air is introduced is formed such that the inner diameter thereof at the outlet side is larger than that at the inlet side. Therefore, the introduced air can be rectified in the area of the reducer pipe 2a whose diameter gradually increases, and reduction in the analysis 25 accuracy due to wind and the like from the outside can be 22 prevented. In addition, the amount of the air that has been sampled can be accurately measured by the sensors, and the accuracy of measurement of the particles adhering to the filter, such as the amount of the particles that have been 5 sampled, can be prevented from being reduced.

Although the sampling box 2d has a cubic shape in the present embodiment, the shape of the sampling box 2d is not particularly limited as long as the air can pass therethrough. In addition, in the present embodiment, the 10 filter attachment plates 2b are placed in the sampling box 2d. However, the filter attachment plates 2b may instead be disposed in the air channel at a position outside the sampling box 2d, as long as the accuracy of measurement of the particles using the filter 2c will not be reduced. For 15 example, as illustrated in Fig. 4, the filter attachment plates 2b may be disposed between the reducer pipe 2a and the sampling box 2d. In this case, it is not necessary to form, for example, the lid to be opened when the filter is replaced, on the sampling box 2d.

20 In addition, in the present embodiment, the sampling box 2d is connected to the fan 3 with the second reducer pipe 2e. However, the second reducer pipe 2e may be formed in, for example, a cylindrical shape as long as sufficient air rectifying effect can be provided by the first reducer 25 pipe 2a. Alternatively, the sampling box 2d may be fixed 23 directly to the fan 3 without placing the second reducer pipe 2e therebetween.

Examples 5 Examples in which the air sampling apparatus according to the present invention was used will now be described. First, the air sampling apparatus 1 illustrated in Fig. 1 was prepared. A portion of the filter 2c exposed to the air had a circular shape with a diameter of 100 mm. A high-10 pressure blower fan (model No. DH2TL manufactured by

Yodogawa Co., Ltd.) was used as the fan 3, and a glass fiber filter with a mesh width of 1 jam (Model No. 61638 manufactured by Pall Corporation) was used as the filter 2c. As a reference, Fig. 5 shows performance curves of the fan 3 15 used in the examples.

The sampling time for sampling the air was set to about 24 hours, and the air was sampled at different locations on different days. The amount of particles adhered to the filter 2c was calculated by comparing the weight of the 20 filter before the sampling process with that after the sampling process. Table 1 shows the measurement results obtained by the examples.

24

Table 1

Amount of ^er. ^ter. Amount of Sampling Sampling Sampling air particles start date location time sampled sampling sampling onfilter _____rn^__g__g__g 1 2009/12/22 !fnd 24 hrs 185.8 0.715 0.865 0.150 ___(Ibaraki)______ 2 2009/12/24 [f nd., 24 hrs 176.4 0.702 0.867 0.165 3 2010/1/5 !fnd 24hrs 167.8 0.727 0.801 0.074 ___(Ibaraki)______

Coast 4 2010/1/7 (Nishino- 23 hrs 163.5 0.734 0.740 0.006 ___miyahama)______

Coast 5 2010/1/8 (Nishino- 23 hrs 171.1 0.717 0.721 0.004 ___miyahama)______

Coast 6 2010/1/9 (Nishino- 24 hrs 174.2 0.723 0.727 0.004 ___miyahama)______

Coast 7 2010/1/10 (Nishino- 22 hrs 161.7 0.711 0.713 0.002 ___miyahama)______ 8 2010/1/13 !fnd 24 hrs 175.0 0.721 0.801 0.080 9 2010/1/21 J^dki) 25 hrs 167.3 0.700 0.801 0.101 10 2010/1/27 |?nd 24 hrs 173.1 0.715 0.790 0.075 ___(Ibaraki)______ 11 2010/1/28 |fnd 24hrs 173.1 0.714 0.782 0.068 ___(Ibaraki)______ 12 2010/2/1 [f nd., 24 hrs 173.1 0.706 0.773 0.067 ___(Ibaraki)______ 13 2010/2/2 |f "d, 24 hrs 173.1 0.701 0.776 0.075 14 2010/2/7 !fnd 24hrs 173.1 0.705 0.797 0.092 15 2010/2/8 Iff, 24 hrs 173.1 0.711 0.777 0.066 ___(Ibaraki)______ 16 2010/2/9 Ifnd,, 24 hrs 173.1 0.755 0.761 0.006 _(Ibaraki) _____ 25

As is clear from the examples shown in Table 1, the amount of the air sampled per unit time was 6.69 m3/hour to 7.74 m3/hour (average 7.23 m3/hour), and measurement results with small variations were obtained at different locations 5 on different dates. In particular, the same amount of air was sampled in Examples Nos. 10 to 16, and it was confirmed that the measurement was performed with a high accuracy under the same conditions.

The invention is not limited to the embodiments 10 described. Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope of the invention as defined in the following claims.

2007089

Claims

An air sampling device comprising: a sample housing into which air to be analyzed is introduced; a reduction pipe provided on the sample housing and having an air inlet at a distal end, the air inlet having a diameter smaller than a diameter of the reduction pipe at a proximal end adjacent to the sampling housing and the diameter of the reduction pipe gradually increases from the distal end to the proximal end, introducing the air into the reduction pipe and passing it into the sample housing from the proximal end of the reduction pipe; a fan that sucks the air into the sample house; a filter provided with an air channel containing the reduction pipe and the sample housing, the filter blocking predetermined particles in the air introduced from the reduction pipe; and a sensor that measures the amount of air flowing through the air duct, a ratio of the particles in the air being determined based on the amount of air and the amount of particles adhering to the filter.

The air sampling device according to claim 1, wherein a mesh size of the filter is in the range of 1 µm to 3 µm.

3. Air sampling device according to claim 1 or 2, further comprising: a pair of clamping elements with openings, wherein the filter is clamped between parts of the clamping elements located around the openings.

The air sampling device according to claim 3, wherein the clamping elements are placed in the sampling housing, and wherein the sampling housing is provided with a lid which is arranged to be opened and closed to allow the filter to be replaced.

An air sampling device according to claim 1 or 2, further comprising: a second reduction pipe attached to the sampling housing, the fan being connected to the sampling housing by means of the second reduction pipe provided between them, and wherein an inner diameter of the second reduction pipe at an end near the fan is larger than an inner diameter of the second reduction pipe at an end near the sampling housing.

An air sampling device according to claim 5, wherein the sensor is provided in the reduction pipe or in the second reduction pipe.

7. Air sampling device according to claim 1 or 2, wherein the sampling housing is made of a transparent or translucent material, and wherein the status of the filter can be observed from outside the sampling housing. 2007089