Patent Publication Number: US-2021162329-A1

Title: Filter leakage monitoring device and particle separator provided with the same

Description:
BACKGROUND 
     Field of the Invention 
     The present invention relates to a filter leakage monitoring device and a particle separator particle separator provided with the monitoring device. More particularly, the present invention relates to, in, for example, a dust collector or the like that uses a plurality of filters, a device that is capable of identifying a filter that has caused leakage when it has become impossible to normally filter to-be-treated air or the like by monitoring particle leakage from each of the filters. 
     Background Art 
     In workshops, etc., such as various factories, in which dust is easily generated, a dust collector is used in order to improve or excellently maintain a working environment. The dust collector has various dust collection methods, and one of these methods is, for example, a circulation processing method in which an atmosphere in a workshop is sucked in, and various particles (dust) dispersing in the atmosphere are then separated by filters, and clean air obtained here is discharged into the atmosphere. Additionally, a cartridge type filter, such as a bag-shaped filter, is widely used as the filter so that maintenance, such as replacement, can be easily performed. 
     A dust collector described in, for example, Non-Patent Literature 1 can be mentioned as one example of the dust collector formed as above. In this dust collector, a casing  90  is partitioned into a lower dust-containing air chamber  91  and an upper clean air chamber  92  as shown in  FIG. 9 , and dust-containing air is treated by a plurality of bag filters  93  disposed in the dust-containing air chamber  91  so that dust is separated from the dust-containing air, and only clean air passes through the clean air chamber  92 , and then passes through a discharge pipe  95 , and is discharged into outside air (see the left half of  FIG. 9 ). Additionally, dust that has adhered to an outer surface of the bag filter  93  is peeled off by a jet (air wash) of compressed air from the clean-air-chamber- 92  side, and can be outwardly discharged by a valve  94  disposed below (see the right half of  FIG. 9 ). 
     CITATION LIST 
     Patent Literature 
     Non-Patent Literature 1: Daiichi Filter Kogyo, Ltd., Pulse Jet Type Dust Collector [Searched on Apr. 10, 2018], Internet &lt;http://www5e.biglobe.ne.jp/˜filter/parusujet.htm&gt; 
     Technical Problem 
     However, the conventional dust collector mentioned above has had the following problems. 
     In detail, there is a case in which the bag filter included in the dust collector is deteriorated by being used for a long time or is damaged by the impact due to the air wash mentioned above, and, as a result, is broken so as to, for example, be torn, thus causing leakage of particles, such as dust, that are to be separated in a normal situation and making it impossible to normally filter air or the like that is to be treated. 
     In this case, it is economical and preferable to identify a bag filter that has caused leakage and to replace only this bag filter. However, most of the materials for a filtering part of the bag filter or the like are cloth made of various synthetic resin fibers, and are soft and are easily deformed, and therefore it has not been easy to find which part of the material has been broken if a broken part is comparatively small, putting aside a case where the broken part is large. Therefore, practically, it has been difficult to identify which one of the plurality of bag filters has been broken. 
     Therefore, ordinarily, all of the bag filters are replaced without identifying a bag filter that has caused leakage when it has become impossible to normally filter air or the like that is to be treated as mentioned above. Although it becomes possible to reliably make repairs by replacing all of the bag filters, a bag filter that has not been broken is also replaced and discarded, and therefore a waste of labor-and-time for replacement and a waste of cost have been non-negligible. 
     Additionally, in the thus-formed dust collector, the number of discharge pipes  95  through which clean air is outwardly discharged might be one if the dust collector is small in size, and yet, in, for example, large-sized dust collectors of a type in which many bag filters are used, there is a dust collector in which many discharge pipes are arranged. In this case, ordinarily, the discharge pipes are arranged side by side in a lateral direction (in a horizontal direction when installed) on the casing  90 , etc., and yet, in a dust collector whose performance has been improved by installing bag filters more closely, there has been a problem in the fact that it becomes difficult to arrange discharge pipes because the arrangement of many discharge pipes becomes overcrowded in the lateral direction. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in consideration of these circumstances, and it is an object of the present invention to provide a filter leakage monitoring device that is capable of monitoring leakage of particles from each of a plurality of filters in, for example, a dust collector or the like that uses such a plurality of filters and that is capable of identifying a filter that has caused leakage when it has become impossible to normally filter air or the like that is to be treated, and to provide a particle separator particle separator provided with the monitoring device. 
     Additionally, it is an object of the present invention to provide a filter leakage monitoring device that is capable of arranging many discharge pipes effortlessly and with enough room even in a dust collector whose performance has been improved by installing bag filters closely together, and to provide a particle separator particle separator provided with the monitoring device. 
     Solution to Problem 
     (1) To achieve the aforementioned objects, a filter leakage monitoring method of a particle separator of the present invention is performed such that, in order to determine that particle leakage has occurred in a filter because of particles flowing through or adhering to the inside of a sampling pipe, air that has passed through each of a plurality of filters from an air intake port that sucks air that has passed through each of the filters into a clean air chamber or from near the air intake port is sucked through the sampling pipe, which corresponds to each of the filters disposed in a particle-containing air chamber into which air containing particles is introduced and which is configured to have a visible part capable of visually recognizing the inside or configured to be capable of detecting particles existing in the inside. 
     According to the filter leakage monitoring method of the particle separator of the present invention, air that has passed through each of the filters from the air intake port that sucks air that has passed through each of the filters into the clean air chamber or from near the air intake port is sucked through the sampling pipe, which corresponds to each of the plurality of filters disposed in the particle-containing air chamber into which air containing particles is introduced and which is configured to have the visible part capable of visually recognizing the inside or configured to be capable of detecting particles existing in the inside, and, as a result, clean air introduced from the air intake port of the filter or air regarded as being clean enters the sampling pipe, and passes through the inside of the sampling pipe. 
     If a filtering part of any of the plurality of filters is broken so as to have a hole, when air containing particles in the particle-containing air chamber is sucked from the clean-air-chamber side and passes through the filter, a part of the particles will leak from the hole, and it will become impossible to reliably separate the particles. Particles that have leaked therefrom pass through the inside of the filter together with clean air, and enter the clean air chamber from the air intake port, and yet a part of the particles is sucked together with surrounding air by means of a sampling pipe whose suction port is positioned at the air intake port or is positioned near the air intake port. 
     Particles that have been sucked by the sampling pipe together with air pass through the inside of the pipe, and a part of the particles adheres to and soils an inner wall of the pipe, and therefore, in the visible part, it is possible to, from outside, visually recognize that the inner wall is dirty. Alternatively, when air containing particles passing through the inside of the pipe is excessively dirty before particles adhere to the inner wall so as to become dirty, it is possible to visually recognize it from outside. Alternatively, it is possible to detect particles passing through the inside of the pipe by means of, for example, various sensors. In any of the aforementioned cases, it is possible to identify a filter that has caused particle leakage by determining that particle leakage has occurred in a filter to which the sampling pipe corresponds. 
     For example, particles of food powder, or particles of chemical powder, or the like, besides particles of dust, can be mentioned as particles that are separated from air, and yet, without being limited to these particles, the present invention can be applied to particles included in other categories. 
     A structure in which a visible part for visually recognizing the inside of a sampling pipe is provided is simple and desirable as a structure of each of the sampling pipes, and yet, instead of this, if the structure is formed to include various sensors, such as a photoelectric sensor or an infrared ray sensor, that detect particles passing through the inside of the pipe, an artificial determination will be excluded, and therefore it can be expected that it becomes possible to identify a defective filter more swiftly and more reliably. 
     (2) To achieve the aforementioned objects, a filter leakage monitoring device of a particle separator of the present invention includes a plurality of sampling pipes each of which is configured to have a visible part through which an inside of the sampling pipe can be visually recognized or each of which is configured so that particles inside the sampling pipe are detectable, a suction port of each of which corresponds to each of a plurality of filters disposed in a particle-containing air chamber into which air containing particles is introduced, the suction port of each of which is positioned at an air intake port that sucks air that has passed through each of the filters into a clean air chamber or is positioned near the air intake port, and a suction device that sucks air through each of the sampling pipes. 
     According to the filter leakage monitoring device of the present invention, the sampling pipe is configured to have the visible part capable of visually recognizing the inside of the sampling pipe or configured to be capable of detecting particles existing in the inside, and the suction port corresponds to each of the plurality of filters disposed in the particle-containing air chamber into which air containing particles is introduced, and it is possible to suck air by means of the suction device through each of the sampling pipes from the intake port that sucks air that has passed through each of the filters into the clean air chamber or from near the air intake port. Hence, clean air introduced from the air intake port of the filter or air regarded as being clean passes through the inside of the sampling pipe. 
     If a filtering part of any of the plurality of filters is broken so as to have a hole, when air containing particles in the particle-containing air chamber is sucked from the clean-air-chamber side and passes through the filter, a part of the particles will leak from the hole, and it will become impossible to reliably separate the particles. Particles that have leaked therefrom pass through the inside of the filter together with clean air, and enter the clean air chamber from the air intake port, and yet a part of the particles is sucked together with surrounding air by means of a sampling pipe whose suction port is positioned at the air intake port or is positioned near the air intake port. 
     Particles that have been sucked by the sampling pipe together with air pass through the inside of the pipe, and a part of the particles adheres to and soils an inner wall of the pipe, and therefore, in the visible part, it is possible to, from outside, visually recognize that the inner wall is dirty. Alternatively, when air containing particles passing through the inside of the pipe is excessively dirty before particles adhere to the inner wall so as to become dirty, it is possible to visually recognize it from outside. Alternatively, it is possible to detect particles passing through the inside of the pipe by means of, for example, various sensors. In any of the aforementioned cases, it is possible to recognize that particle leakage has occurred in a filter to which the sampling pipe corresponds, and it is possible to identify a filter that has caused particle leakage. 
     The term “suction device” mentioned in the claims denotes a device capable of making negative pressure (for example, air pressure lower than the atmospheric pressure) of a vacuum pump, or a blower, or the like, and its method and its structure are not restricted. 
     (3) The present invention may be configured such that a suction/discharge passage through which air is sucked and discharged by the suction device is connected to a discharge passage through which clean air passing through the clean air chamber is sucked and discharged outwardly from the device. 
     In this case, when particle leakage has occurred in a filter, particles that have passed through this filter and through the inside of the sampling pipe meet clean air passing through the discharge passage together with clean air passing through another sampling pipe, and are discharged to external air existing outside the device. If a suction passage is configured to be connected to the discharge passage, it is also possible to employ a configuration formed such that air passing through each of the sampling pipes is sucked by using the suction force of the suction device, for example, without providing the suction device at the suction passage. 
     (4) The present invention may be configured such that the sampling pipes corresponding to the filters that are arranged side by side and that are respectively identical in row with the sampling pipes are disposed in a lengthwise arrangement. 
     In this case, the plurality of sampling pipes are disposed in a lengthwise arrangement (arrangement in the vertical direction), and, as a result, a laterally (horizontally) larger space for arranging the sampling pipes side by side is not required than in a configuration in which the sampling pipes are disposed in a lateral arrangement. This makes it possible to arrange many sampling pipes each of which is a discharge pipe effortlessly and with enough room so as not to become overcrowded even if it is a dust collector whose performance has been improved by closely installing bag filters. 
     (5) To achieve the aforementioned objects, a particle separator of the present invention includes a particle-containing air chamber that is provided with a plurality of filters and into which particle-containing air that contains particles is introduced, a clean air chamber that is divided from the particle-containing air chamber by means of the filters and into which air that has passed through the filters is introduced, a plurality of sampling pipes that are disposed in the clean air chamber each of which is configured to have a visible part through which an inside of the sampling pipe can be visually recognized or each of which is configured so that particles inside the sampling pipe are detectable, a suction port of each of which corresponds to each of a plurality of filters disposed in a particle-containing air chamber into which air containing particles is introduced, the suction port of each of which is positioned at an air intake port that sucks air that has passed through each of the filters into the clean air chamber or is positioned near the air intake port, and a filter leakage monitoring device having a suction device that sucks air through each of the sampling pipes. 
     According to the particle separator of the present invention, air is sucked from the clean-air-chamber side, and, as a result, particle-containing air that contains particles is introduced into the particle-containing air chamber. The particle-containing air passes through the filter, and particles in the particle-containing air are filtered off, and are separated from air. Clean air from which particles have been separated enters the clean air chamber from the air intake port, and is sent to a discharge passage connected to the clean air chamber, and is discharged into external air. 
     Additionally, clean air introduced from the air intake port of the filter or air regarded as being clean is sucked by the suction device through each of the sampling pipes, and passes through the inside of the sampling pipe. If any of the plurality of filters is broken so as to have a hole, when air containing particles in the particle-containing air chamber passes through the filter, a part of the particles will leak from the hole, and it will become impossible to reliably separate the particles. 
     Additionally, particles that have leaked therefrom pass through the filter together with clean air, and enter the clean air chamber from the air intake port, and a part of the particles is sucked by the suction device through a sampling pipe corresponding to a filter that has occurred leakage together with its surrounding air. Particles that have been sucked by the sampling pipe together with air pass through the inside of the pipe, and a part of the particles adheres to and soils an inner wall of the pipe, and therefore, in the visible part, it is possible to, from outside, visually recognize that the inner wall is dirty. 
     Alternatively, when air containing particles passing through the inside of the pipe is excessively dirty before particles adhere to the inner wall so as to become dirty, it is possible to visually recognize it from outside. Alternatively, it is possible to detect particles passing through the inside of the pipe by means of, for example, various sensors. In any of the aforementioned cases, it is possible to recognize that particle leakage has occurred in a filter to which the sampling pipe corresponds, and it is possible to identify a filter that has caused particle leakage. 
     (6) The present invention may be configured such that mutually different symbols are respectively assigned to the filters and are displayed, and a symbol identical with the symbol of each of the filters corresponding each of the sampling pipes is assigned to the sampling pipe and is displayed. 
     In this case, if the visible part of one of the sampling pipes that displays a symbol is dirty, it is understood that leakage has occurred in one of the filters that displays the same symbol as that of the sampling pipe that is dirty. As thus described, it is possible to easily and reliably identify a filter that has been broken by collating the symbols with each other. 
     The term “symbol” mentioned in the claims includes letters, numeric characters, marks, emblems, etc., that are used to represent predetermined contents. 
     A dust collector can be mentioned as an example of the particle separator provided with the filter leakage monitoring device. Additionally, a powder mixer (blender) to which a function to stir a plurality of kinds of powders and to mix the powders together at an appropriate ratio is added can be mentioned as a device in which other functionalities are added to the particle separator. 
     Advantages of the Invention 
     The present invention is capable of providing a filter leakage monitoring device that is capable of monitoring leakage of particles from each of a plurality of filters in, for example, a dust collector or the like that uses such a plurality of filters and that is capable of identifying a filter that has caused leakage when it has become impossible to normally filter air or the like that is to be treated, and providing a particle separator particle separator provided with the monitoring device. 
     Additionally, a plurality of sampling pipes are disposed in a lengthwise arrangement (arrangement in the vertical direction), and, as a result, a laterally (horizontally) larger space for arranging the sampling pipes side by side is not required than in a configuration in which the sampling pipes are disposed in a lateral arrangement. This makes it possible to arrange many sampling pipes each of which is a discharge pipe effortlessly and with enough room so as not to become overcrowded even if it is a dust collector whose performance has been improved by closely installing bag filters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a descriptive front view showing a first embodiment of a particle separator according to the present invention; 
         FIG. 2  is a descriptive plan view of the particle separator according to the present invention; 
         FIG. 3  is a descriptive lateral view of the particle separator according to the present invention; 
         FIG. 4  shows a main part of a sampling pipe of the particle separator of  FIGS. 1 to 3 , in which  FIG. 4A  is a descriptive enlarged view of a P 1  part of  FIG. 1 ,  FIG. 4B  is a descriptive enlarged view of a P 2  part of  FIG. 2 , and  FIG. 4C  is a descriptive enlarged view of a P 3  part of  FIG. 3 ; 
         FIG. 5  is a descriptive enlarged view of a P part of  FIG. 4C ; 
         FIG. 6  shows a second embodiment of the particle separator according to the present invention, in which  FIG. 6A  is a descriptive front view, and  FIG. 6B  is a descriptive plan view; 
         FIG. 7  is a descriptive enlarged view of a P 4  part showing a main part of a sampling pipe of the particle separator of  FIG. 6 ; 
         FIG. 8  is a descriptive view showing a third embodiment of the particle separator according to the present invention; and 
         FIG. 9  is a descriptive view showing a structure of a dust collector described in Non-Patent Literature 1. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will be described in more detail. 
     Referring to  FIG. 1  to  FIG. 4 , a description will be given of a structure of a dust collector A 1  that is a first embodiment of a particle separation device according to the present invention. It should be noted that a barrel part of a casing body is partially omitted in  FIG. 1 , an upper surface plate of the casing body is omitted in  FIG. 2 , and the barrel part of the casing body is partially omitted in  FIG. 3 , so that bag filters disposed inside appear. 
     The dust collector A 1  includes a casing  1 , a filter leakage monitoring device  2 , and a vacuum pump  18 . The casing  1  includes a casing body  10  whose barrel part formed in a quadrangular cylindrical shape and whose upper part is closed with an upper surface plate  101  and a hopper  11  that is disposed at a lower part of the casing body  10  and that downwardly becomes narrower. A double damper  12  that transfers particles, which have been separated and collected, to a dust collection container  120  is attached to a lower end part of the hopper  11 . The double damper  12  has a structure in which two valves are placed on upper and lower sides, respectively, and discharges particles to the dust collection container  120 , which is detachable, while opening and closing each of the valves in a time-difference manner. 
     In the casing  1 , a particle-containing air chamber  13  into which particle-containing air that contains particles is introduced is formed on the lower-part side, whereas a clean air chamber  16  through which clean air, from which particles have been separated, passes is disposed on the upper-part side. The particle-containing air chamber  13  and the clean air chamber  16  are divided from each other by means of a divider plate  14  and a plurality of bag filters  15 . Additionally, an introduction pipe  102  that introduces external air (particle-containing air) into the particle-containing air chamber  13  is disposed at a sidewall (whose reference sign is omitted) of the particle-containing air chamber  13 . 
     Each of the bag filters  15  has a bag part formed in a bottomed cylindrical shape (whose reference sign is omitted), and the bag part is made of synthetic resinous cloth that has a texture that is capable of filtering and separating particles each of which has a fixed size. With respect to this texture, a texture size that can correspond to the size of a to-be-separated particle is appropriately employed. Additionally, a reinforcing frame (not shown) of a synthetic-resin-made wire rod or the like is lined on the inner-surface side of the bag part so that the bag part is not destroyed by a difference in air pressure between the inside and the outside. 
     In the bag filter  15 , the opening side of the bag part is attached to a circular installation port  140  (also see  FIG. 4 ) that is formed at seven places vertically, at six places laterally, and at forty-two places in total of the divider plate  14  in  FIG. 2 . Each of the bag filters  15  is formed so that an air intake port  150  is open toward the clean-air-chamber- 16  side as shown in  FIG. 1  and  FIG. 4A  that is an enlarged view of the P 1  part, and the bag part is positioned on the particle-containing-air-chamber- 13  side, and is disposed so that the bag parts uniformly droop down. Hence, clean air from which particles have been separated in each of the bag filters  15  is sucked from the air intake port  150  into the clean air chamber  16 . 
     A plurality of metallic sampling pipes  20  that are constituents of the filter leakage monitoring device  2  are disposed in the clean air chamber  16 . The sampling pipes  20  are each extended from the air intake port  150  of each of the bag filters  15  in the lateral direction in  FIG. 2 , and are arranged side by side in the horizontal direction when installed. In detail as shown in  FIG. 4B  (an enlarged view of the P 2  part of  FIG. 2 ), a sampling pipe  20   a  whose front-end suction port (reference sign omitted) is positioned near the air intake port  150  of the leftmost bag filter  15   a  is hung at a pulse-jet pipe  24  laid horizontally, and is extended as above, and is connected to an air intake pipe  21 . The material of the sampling pipe  20  is not limited to a metallic material, and any kind of material (for example, synthetic resin) may be employed. 
     The pulse-jet pipe  24  is provided with an air receiver tank  240  at its end side, and air washing can be performed such that particles, such as dust, that have adhered to an outer surface of the bag filter  15  are peeled off by a jet (pulse jet) of compressed air from the pulse-jet pipe  24  disposed on the clean-air-chamber- 16  side by use of the air receiver tank  240  while operating the dust collector A 1 . 
     Likewise, a sampling pipe  20   b  is extended from a bag filter  15   b,  a sampling pipe  20   c  is extended from a bag filter  15   c,  a sampling pipe  20   d  is extended from a bag filter  15   d,  a sampling pipe  20   e  is extended from a bag filter  15   e,  and a sampling pipe  20   f  is extended from a bag filter  15   f  successively, and is connected to the air intake pipe  21  that is disposed outside the casing  1  and that is laid in the horizontal direction. 
     Additionally, in each of the sampling pipes  20  (in the description of  FIG. 4 , the sampling pipes  20   a  to  20   f ), visible parts  200  that are arranged side by side in the direction along the air intake pipe  21  and each of which uniformly has a predetermined length are formed before entering the air intake pipe  21 . The visible part  200  is placed in the vertical direction, and is made of transparent synthetic resin unlike other parts of each of the sampling pipes  20 , thus making it possible to see the inside of the pipe from the outside through the visible part  200  (see  FIG. 4C  that is an enlarged view of the P 3  part of  FIG. 3 ). 
     Valves (whose reference sign is omitted) are respectively disposed at both ends of the visible part  200  in a direction in which intake air flows, thus making it possible to perform switching between the passage and the blockage of intake air. The material of the visible part  200  is not limited to synthetic resin, and the visible part  200  can be made of another material, such as tempered glass or heat-resistant glass. 
     Additionally, in each of all the forty-two bag filters  15 , a number  151  is assigned and displayed on an attachment piece (whose reference sign is omitted) of each of the bag filters  15  in the manner of consecutive numbers “1 to 42” (see  FIGS. 4A and 4C ). Additionally, likewise, a number  201  is assigned and displayed on each of all the forty-two sampling pipes  20  corresponding to each of the bag filters  15  in the manner of consecutive numbers “1 to 42” (see  FIG. 5 ). In  FIG. 4  and  FIG. 5  that is an enlarged view of the P part of  FIG. 4C , the number  151  of each of the bag filters  15  and the number  201  of each of the sampling pipes  20  are partially omitted and are partially not displayed for drawing convenience. 
     It is possible to visually recognize the number  151  of each of the bag filters  15  by opening a door (whose reference sign is omitted) of the casing  1 . Additionally, the number  151  is displayed on the attachment piece, and therefore, if a bag filter has become defective, it is only necessary to replace only a filter body, which is a common spare part, with another, hence enabling an economical operation. Additionally, likewise, in a particle separation device A 2  described later, it is possible to number each of the bag filters  15  and each of the sampling pipes  20 . 
     The air intake pipe  21  mentioned above is connected to the intake side of a vacuum pump  22  that is a suction device. An exhaust pipe  23  is connected to the exhaust side of the vacuum pump  22 . On the other hand, an air intake pipe  17  is connected to the clean air chamber  16 . The air intake pipe  17  is connected to the intake side of the vacuum pump  18 . An exhaust pipe  19  is connected to the exhaust side of the vacuum pump  18  (see  FIG. 1 ). The exhaust pipe  23  mentioned above is connected to a part closer to a base end of the exhaust pipe  19 . 
     It is also possible not to contaminate external air by providing the exhaust pipe  19  with a filter even when particles have leaked. Additionally, air that has passed through the exhaust pipe  23  may be discharged directly to external air without connecting the exhaust pipe  23  to the exhaust pipe  19 . In that case, it is preferable not to contaminate external air by providing the exhaust pipe  23  with a filter even when particles have leaked, and yet the present invention is not limited to this configuration. 
     (Operation) 
     The operation of the dust collector A 1  will be described with reference to  FIG. 1  to  FIG. 4 . In the dust collector A 1 , the inside of the casing  1  becomes negative in pressure by operating the vacuum pump  18 . Hence, air (external air that contains particles, such as dust) is taken in from the introduction pipe  102 , and air taken in the casing  1  is drawn by the vacuum pump  18 , and continuously flows from the particle-containing air chamber  13  to the clean air chamber  16 . 
     When air moves from the particle-containing air chamber  13  to the clean air chamber  16 , the air passes through each of the bag filters  15 , and particles, such as dust, in the air are filtered, and adhere to the outer surface of each of the bag filters  15 , and are separated as shown by the arrows in  FIG. 1  and  FIG. 4A . The air (hereinafter, referred to as clean air) from which particles have been separated and that has become clean enters the clean air chamber  16 , and then passes through the air intake pipe  17  connected to the vacuum pump  18 , and is discharged from the exhaust pipe  19  into external air. This makes it possible to improve a working environment while gradually cleaning the air in a workshop or the like. 
     On the other hand, the clean air from which particles have been separated with each of the bag filters  15  by means of the filter leakage monitoring device  2  included in the dust collector A 1  is sucked by the vacuum pump  22  from near the air intake port  150  formed on the clean-air-chamber- 16  side through each of the sampling pipes  20 . The clean air passing through each of the sampling pipes  20  passes through the visible part  200  disposed in a route, and then passes through the exhaust pipe  23 , and gathers at the air intake pipe  17  mentioned above. 
     If a filtering part of any of the plurality of bag filters  15  is broken so as to have a hole, when air containing particles in the particle-containing air chamber  13  is sucked from the clean-air-chamber- 16  side and passes through the bag filter  15 , a part of the particles will leak from the hole, and it will become impossible to reliably separate the particles. Particles that have leaked therefrom pass through the inside of the bag filter  15  together with clean air, and enter the clean air chamber  16  from the air intake port  150 , and yet a part of the particles is sucked together with surrounding air by means of the sampling pipe  20  whose suction port is positioned near the air intake port  150 . 
     Particles that have been sucked by the sampling pipe  20  together with air pass through the inside of the pipe, and a part of the particles adheres to and soils the inner wall of the pipe, and therefore, in the visible part  200 , it is possible to, from outside, visually recognize that the inner wall is dirty. Alternatively, when air containing particles passing through the inside of the pipe is excessively dirty before particles adhere to the inner wall so as to become dirty, it is possible to visually recognize it from outside. 
     If particles adhere to the inside of the sampling pipe  20  so that the inner surface of the pipe becomes dirty, it is possible to remove particles adhering thereto by means of an airflow by temporarily closing the valve and then opening it at once and by allowing air to rapidly pass during operation. 
     In any of the aforementioned cases, it is possible to understand that particle leakage has occurred in a bag filter  15  to which the sampling pipe  20  corresponds, and it is possible to identify a bag filter  15  that has caused particle leakage. 
     In other words, if the visible part  200  of the number  201  that displays “2” is dirty among the numbers  201  of the sampling pipes  20  in, for example,  FIG. 5 , it is understood that leakage has occurred in the bag filter  15  that displays “2” that is the same number among the numbers  151  of the bag filters  15 . As thus described, it is possible to easily and reliably identify a bag filter that has been broken by collating the numbers  201  and  151  with each other. 
     Hence, likewise, when leakage has occurred in a bag filter  15 , it is only necessary to replace only the bag filter  15  that has caused leakage, and therefore it is possible to eliminate a waste of labor-and-time for replacement of all filters, which has been performed in a conventional technique, and a waste of cost. 
     In the dust collector A 1 , the exhaust pipe  23 , through which exhaust gases are discharged by the vacuum pump  22 , is connected to the air intake pipe  17 , which is connected to the vacuum pump  18  that sucks clean air passing through the clean air chamber  16  and discharges it outwardly from the device through the exhaust pipe  19 . Hence, when particle leakage has occurred in a bag filter  15 , particles that have passed through the inside of the sampling pipe  15  that has sucked the particles meet clean air passing through the air intake pipe  17  together with clean air passing through the other sampling pipes  15 , and are discharged from the exhaust pipe  19  into external air outside the device. 
     Referring to  FIG. 6  and  FIG. 7 , a description will be given of a structure of a dust collector A 2  that is a second embodiment of the particle separation device according to the present invention. It should be noted that a barrel part of a casing body is partially omitted in  FIG. 6A , and an upper surface plate of the casing body is omitted in  FIG. 6B , and the barrel part of the casing body is omitted in  FIG. 7 , so that a bag filter disposed inside appears. 
     The dust collector A 2  has the same structure as the aforementioned dust collector A 1  excluding a configuration in which sampling pipes  20  each of which is a constituent of a filter leakage monitoring device  2   a  and that respectively correspond to bag filters  15 , which are arranged side by side and which are respectively identical in row with the sampling pipes  20 , are disposed in a lengthwise arrangement (arrangement it the vertical direction when installed). In the following description, only a difference mentioned above in comparison with the dust collector A 1  is described, and a description of the other parts is omitted, and, in  FIG. 6  and  FIG. 7 , a same reference sign is given to a component equivalent to each component of the dust collector A 1 , and the description of the dust collector A 1  is quoted herein. 
     This embodiment is described with reference chiefly to  FIG. 7  that is an enlarged view of the P 4  part of  FIG. 6A . The sampling pipes  20  are each extended from the air intake port  150  of each of the bag filters  15  in the lateral direction in  FIG. 6 , and are disposed so as to be arranged in the vertical direction when installed. In detail, a sampling pipe  20   g  whose front-end suction port (whose reference sign is omitted) is positioned near the air intake port  150  of the leftmost bag filter  15   a  is extended as above, and is connected to the air intake pipe  21 . 
     Likewise, a sampling pipe  20   h  is extended from the bag filter  15   b  while passing directly below the sampling pipe  20   g,  and a sampling pipe  20   i  is extended from the bag filter  15   c  while passing directly below the sampling pipe  20   h.    
     Furthermore, a sampling pipe  20   j  is extended from the bag filter  15   d  while passing directly below the sampling pipe  20   i , and a sampling pipe  20   k  is extended from the bag filter  15   e  while passing directly below the sampling pipe  20   j , and a sampling pipe  20   m  is extended from the bag filter  15   f  while passing directly below the sampling pipe  20   k  successively, and is connected to the air intake pipe  21  that is disposed outside the casing  1 . 
     In the present embodiment, parts of the sampling pipes  20  each of which serves as a visible part  200   a  are arranged side by side along the air intake pipe  21  in the same way as the visible part  200  of the dust collector A 1 , so that the inside of a sampling pipe  20  corresponding to a bag filter  15  that has caused particle leakage can be easily seen through the visible part  200   a.    
     The dust collector A 2  is configured as above, and the plurality of sampling pipes  20  are disposed in a lengthwise arrangement, i.e., are disposed to be arranged in the vertical direction when installed, and, as a result, a laterally larger space for arranging the sampling pipes  20  side by side is not required than in a configuration in which the sampling pipes  20  are laterally arranged as in the dust collector A 1 . This makes it possible to arrange many sampling pipes each of which is a discharge pipe effortlessly and with enough room so as not to become overcrowded even if it is a dust collector whose performance has been improved by closely installing the bag filters. 
     Referring to  FIG. 8 , a description will be given of a structure of a powder mixer A 3  that is a third embodiment of the particle separation device according to the present invention. The powder mixer A 3  is a so-called blender, and is to evenly mix powders of, for example, foods or medicines at a predetermined ratio. 
     In the powder mixer A 3 , the clean air chamber  16  leading to an air intake pipe  17   a  and the particle-containing air chamber  13  that is a mixing chamber (both of which are not shown) are disposed in a casing  10   a,  and, in the particle-containing air chamber  13 , the plurality of bag filters  15  are arranged in the same way as in the dust collector A 1 , and the filter leakage monitoring device  2  (not shown) is disposed. 
     According to the powder mixer A 3 , it is possible to stir a plurality of kinds of powders introduced into the casing  10   a  through the introduction pipe  102  by means of compressed air supplied from a compressed-air supply part  103  laterally connected to a lower part of a hopper  11   a  and is possible to discharge evenly-mixed powders outwardly from a discharge valve  104 . It is possible to see how the powders are being stirred through a peephole  105 . 
     Additionally, in the powder mixer A 3 , the internal pressure is maintained near the atmospheric pressure during a stirring operation, and therefore compressed air introduced thereinto is required to be discharged outwardly therefrom. At this time, to avoid allowing powders floating in the particle-containing air chamber  13  to be discharged outwardly together with air, powders are separated by the bag filter  15  in the same way as in the dust collector A 1 , and air is discharged into external air through the air intake pipe  17   a.    
     If any of the bag filters  15  is broken, and powder leakage occurs, it is possible to identify a bag filter  15  that has caused leakage by visually recognizing dirt, which is caused by the passage of powders, of a sampling pipe  20  corresponding to each of the bag filters  15  in the same way as in the dust collector A 1 . Hence, likewise, when leakage has occurred in a bag filter  15 , it is only necessary to replace only the bag filter  15  that has caused leakage, and therefore it is possible to eliminate a waste of labor-and-time for replacement of all filters, which has been performed in a conventional technique, and a waste of cost. 
     Terms and expressions used in the description and in the claims are thoroughly explanatory ones, i.e., are not limiting ones at all, and there is no intention of excluding characteristics mentioned in the description and in the claims and no intention of excluding terms and expressions that are equivalent to a part the characteristics. Additionally, of course, various modifications can be carried out within the range of the technical thought of the present invention. 
     DESCRIPTION OF REFERENCE NUMERALS 
     A 1 : Dust collector 
       1 : Casing 
       10 : Casing body 
       101 : Upper surface plate 
       102 : Introduction pipe 
       11 : Hopper 
       12 : Double damper 
       120 : Dust collection container 
       13 : Particle-containing air chamber 
       14 : Divider plate,  140 : Installation port 
       15  ( 15   a  to  15   f ): Bag filter 
       150 : Air intake port 
       151 : Filter number 
       16 : Clean air chamber 
       17 : Air intake pipe 
       18 : Vacuum pump 
       19 : Exhaust pipe 
       2 : Filter leakage monitoring device 
       20  ( 20   a  to  20   f ): Sampling pipe 
       200 : Visible part 
       201 : Sampling-pipe number 
       21 : Air intake pipe 
       22 : Vacuum pump 
       23 : Exhaust pipe 
       24 : Supporting member 
       240 : Air receiver tank 
     A 2 : Dust collector 
     
       2 
       a: Filter leakage monitoring device  
     
       20   g  to  20   m:  Sampling pipe 
       200   a:  Visible part 
     A 3 : Powder mixer 
       10   a:  Casing 
       103 : Compressed-air supply part 
       104 : Discharge valve 
       105 : Peephole 
       11   a:  Hopper 
     
       17 
       a: Air intake pipe