Measuring and testing – Sampler – sample handling – etc. – Capture device
Reexamination Certificate
2002-12-19
2004-10-26
Cygan, Michael (Department: 2855)
Measuring and testing
Sampler, sample handling, etc.
Capture device
C073S028020
Reexamination Certificate
active
06807874
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The invention relates to a collecting device for collecting floating dusts in the atmosphere.
Among the fine particles floating in the atmosphere, those particles having a diameter less than 10 &mgr;m are called suspended particle matter (SPM). Although these floating dusts contain sands, they are mainly composed of black smokes, unburned materials, sulfur compounds and the like (35% of these is generated from diesel engine cars in the Kanto District, Japan), and it is said that they are highly toxic. The dusts from the exhaust gas from the diesel engine car are specially called diesel exhaust particles (DEP). Also, the particles floating in the atmosphere having a particle smaller than 2.5 &mgr;m are called micro-particulate matter (PM2.5), and have been extensively researched and studied. It is said that the exhaust gas from the diesel engine car is a likely source of the PM2.5.
In addition, as the particulate matters floating in the atmosphere, the yellow sands can be mentioned. The yellow sands are blown up by strong wind at inland desert of Chinese Continent and carried to Japan over the sea by the strong westerlies. Although particle diameters of the yellow sands differ depending on a location, the yellow sands in Chinese Continent near the desert have particle diameters in a range of 20 to 30 &mgr;m, and the particles reaching Japan far from the desert have diameters in the order of 4 to 5 &mgr;m.
Further, the particulate matters floating in the atmosphere include pollens. Recently, with increase in the number of people who suffered from a variety of pollinosis, information on the pollens floating in the atmosphere becomes important. The pollens of Japanese cedars and Japanese cypresses are said to be main causes of the pollinosis. The pollens of these plants have substantially a sphere shape with a diameter in the order of 30 to 50 &mgr;m.
As a method for measuring the floating dusts described above, there has been a method wherein the atmosphere is sucked in and passed through a filter to collect the floating dusts on the filter. Then, a microscope is used to observe the dusts for determining shapes and the number of the particles. There has been also a method wherein the floating dusts in a certain volume of the atmosphere are collected on the filter in the above-stated method, and weights of the filter before and after the collection are measured to obtain the quantity of the particles. In addition, there has been a method wherein the floating dusts collected on the filter in the same manner as described above are processed, and the extracted chemical components contained in the floating dusts are identified by a gas chromatograph mass spectrometer, liquid chromatograph mass spectrometer or spectrum analyzer.
Also, to measure a particle size distribution of the floating dusts (SPM) and micro-particulate matters (PM2.5) in the atmosphere described above, a cascade-impactor type device has been practically used. The cascade-impactor type device utilizes an impacting process of suddenly changing a flow direction of a medium with the particles through colliding against a collecting plate, thereby separating the particles with a specific size from the medium. The cascade-impactor type device is structured such that a plurality of impactors, each having a 50% collecting efficiency at a specific particle diameter, is connected in series of multi-stage. A particle diameter of the dusts collected with the 50% efficiency at each stage represents an average particle diameter for each stage. Thus, the particle size distribution can be obtained from the quantity of the dusts collected from each stage.
Also, as a collecting method of the pollens floating in the atmosphere, a slide glass with an adhesive such as Vaseline coated on a surface has been used. The slide glass with the adhesive thereon is placed in the atmosphere, thereby allowing the pollens in the atmosphere to fall down thereon. The pollens adhered to the slide glass are observed by the microscope to thereby measure a shape, size, number, kind and the like.
Also, as a method for measuring a concentration of the floating dusts, there has been used a method wherein a certain volume of the atmosphere is sucked in and passed through a filter to trap the dusts therein. Then, weights of the filter before and after the collection are measured with an electronic balance or the like. The concentration of the floating dusts in the certain volume of the atmosphere can be determined from the weight difference.
Also, as a device for effectively collecting the floating dusts in the atmosphere, an electrostatic-type particle collector has been known. In the electrostatic-type device, the particles floating in the atmosphere are charged by ions generated from a discharge electrode. A dust-collecting electrode with a different potential relative to the discharge electrode is disposed to collect the charged particles. As the discharge electrode, a discharge electrode as shown in
FIG. 14
has been often used in the electrostatic-type particle collector. The discharge electrode is formed of a number, i.e. several hundreds, of metal wires, and the wires are bundled with a brush tip at one end.
In the collecting method using the filter to analyze SPM and PM2.5 with the microscope or various chemical analyzing instruments, it is very difficult to extract the floating dust individually. Therefore, in the case of the microscopic observation, the floating dusts adhered to the filter are observed with the microscope as they are. In this case, the particle image may be blurred because of a background filter image. Also, in the case of conducting various chemical analyses, since the floating dusts are difficult to remove from the filter, it is difficult to do the analyses. For example, in the case of a fluorescent X-ray analyzer, it is difficult to irradiate the X-ray only on the particles.
Further, it is difficult to conduct the spectrum analysis, since the floating dusts are not separated each other on the filter and electromagnetic wave is difficult to focus on a single particle. Also, the gas chromatograph mass spectrometer or the like is difficult to apply as the floating dusts are hardly separated from the filter.
In the conventional method for measuring the concentration of the floating dusts, the filter is easy to absorb water, thereby causing an error in measuring the floating dusts due to the absorbed water. Also, in this method, it is necessary to weigh the filter twice. Therefore, it is difficult to measure a real time change in the concentration, and the work is also troublesome.
Moreover, in the case that a laser diffraction particle size analyzer is used to determine the particle size distribution, it is necessary to irradiate a laser beam to the floating dusts having a concentration within a specific range to obtain appropriate diffracted or scattered light. In order to provide the floating dusts in the concentration range suitable for the measurement, for example, a specific quantity of the floating dusts may be collected through suction of the atmosphere for a certain period of time. However, the concentration of the floating dusts in the atmosphere is not constant and varies even during the collecting operation. Thus, at the time point when the collecting is completed, the quantity of the floating dusts is totally different from an expected value, and it is difficult to obtain a sample at a desired concentration.
Also, it takes long time to collect the pollens on the surface of the slide glass, for example, 24 hours, in the conventional method for collecting the pollens floating in the atmosphere. Also, a collected quantity per a specific period of time is influenced by wind and the like, so the collected quantity does not represent the actual pollen quantity existing in the atmosphere.
Also, when the microscope is used to observe the collected pollens, it is relatively easy to identify the shape and kind of the pollens. However, the information does not represent the who
Cygan Michael
Kanesaka Manabu
Shimadzu Corporation
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