Abstract: Disclosed is a method and a filter unit for depleting or enriching a liquid or gas with substance(s) comprising i) providing a filter unit comprising at least one convective layer and at least one receiving layer adjacent one another, ii) passing the liquid or gas through the filter so that the main direction of flow is along the layers and the main flow of liquid gas is in the convective layer, allowing the substance(s) to: a) be transferred from a convective layer to a receiving layer, and b) be retained or otherwise modified or transferred within a receiving layer, or c) be provided by the receiving layer, and d) be transferred from the receiving layer to the fluid in the convective layer.

Abstract: System for extracting vapour and particulates from a flow of at least an air stream, the air stream including vapour and particulates, the system having a funnel and a filter unit; an opening of the funnel being arranged for receiving the flow of at least the air stream; an outlet of the funnel being connected to an inlet of the filter unit, the inlet of the filter unit being arranged for receiving the air stream, wherein the filter unit further includes a housing, a first filter and a second filter, a ventilation unit and a filter unit outlet; the housing having a first, second and third chamber; the first chamber and second chamber being separated by the first filter, the second chamber and third chamber being separated by the second filter; the inlet of the filter unit being located in the first chamber; the ventilation unit being located between the third chamber and the filter unit outlet and being arranged during use for creating an underpressure in the first, second and third chambers, the underpressur

Abstract: An apparatus and a method for filtering sectioning wastes of a microtome that are present in an air stream is suggested. The apparatus encompasses an aspiration device. With the aspiration device, sectioning waste can be aspirated from a blade region of the microtome with an air stream. The aspiration device comprises a main filter in which the sectioning wastes can be filtered from the air. In order to allow inadvertently aspirated histological sections to be retrieved again without mix-up, the apparatus according to the present invention has an aspiration device comprising a prefilter that is arranged between the blade region and the main filter and prefilters the sectioning wastes. The present invention further relates to a microtome.

Abstract: A substrate has corrugated sheet(s) and channel(s) for treating exhaust gases of combustion engines. The present invention also relates to methods for manufacturing and using the substrate having the open channel(s). The substrate (1) includes at least one corrugated sheet (3) having depressions (3d) and one flat wire mesh sheet (2) having depressions (2d) which is connected to the corrugated sheet (3) and between the flat wire mesh sheet (2) and the corrugated sheet (3) there are at least partially open channels (POC) for exhaust gas (EG) flow, and the depth of depression (2d) of the flat wire mesh sheet (2) is 0.05-2.0 mm smaller than the height of the corrugation (3c) of the corrugated sheet (3).

Abstract: A system for providing air substantially free from radioactive and toxic contaminates to a nuclear reactor habitability area is provided. The system can include at least one emergency air filtration unit structured and operable to provide air free from radioactive and toxic contaminates to the habitability area. The system can additionally include at least one stored energy power source structured and operable to provide operating power to each emergency air filtration unit.

Abstract: A filter includes at least two different adsorptive media. First, chemisorptive media, which is porous and includes an acidic functional group, is used to remove molecular bases, including ammonia, organic amines, imides and aminoalchols, from the atmosphere used in semiconductor fabrication and other processes that require uncontaminated gaseous environments of high quality. Second, physisorptive media is able to adsorb condensable contaminants, particularly those having a boiling point greater than 150 degrees C. The physisorptive media can include untreated, activated carbon.

Abstract: A water purification system comprising a thermal hydrolysis catalytic reactor, an adsorbent media bed and a reverse osmosis unit is provided. The water purification system may provide potable water from non-potable water, such as non-potable water contaminated with chemical warfare agents, biological warfare agents, radioactive agents and/or Toxic Industrial Chemicals (TICs). Methods for providing potable water using the water purification system of the present invention are also provided.

Abstract: Systems are described for use in removing toxic airborne contaminants from a waxing environment where wax is being applied to sporting equipment. The systems include a base, at least one platform coupled to the base and an airflow generator. The at least one platform is configured to securely receive sporting equipment to be waxed. Each platform includes a first surface that is in contact with the waxing environment, an opposing second surface and at least one opening that extends between the first and second surfaces of each platform. The airflow generator is configured to generate an airflow for pulling harmful airborne contaminants through the at least one opening in each platform in a direction from the first surface to the second surface.

Abstract: A dust collection device for a sanding tool comprising a bag having a sidewall and a coupler attached to the bag. The sidewall comprising a first filter layer, a second filter layer, and an outer support layer. The first filter layer comprising a plurality of fibrillated electrostatically charged electret fibers forming a nonwoven web; the first filter layer having a total pressure drop between about 0.1 to about 4.0 mm H2O, and the first filter layer having a total basis weight between about 50 to about 450 gram/m2. The second filter layer comprising a melt blown microfiber nonwoven web; the second filter layer having a total pressure drop between about between about 5.5 to about 20.0 mm H20, and the second filter layer having a total basis weight between about 15 to about 75 grams/m2.

Abstract: A filter element having multiple formed layers of filtration media is disclosed. The media are layered so as to form a pore size gradient. The filter element is capable of removing both solid and liquid particulates from a moving fluid stream. The filter element has high strength and compressibility. The layers can be supported on a porous or perforate support to provide mechanical stability during filtering operations. The filtration media layers can be formed into various filter element forms such as panels, cartridges, inserts, and the like.

Abstract: An apparatus for air filtration comprises a substrate, the substrate including a first side and a second side, a plurality of openings in the substrate, each opening in the plurality of openings including a tapered edge from the first side to the second side, a plurality of layers of filter material removably attached to the substrate, the plurality of layers of filter material further including: an exposed layer and at least one subsequent layer, a plurality of openings in the plurality of layers, each opening of the plurality of openings corresponding to the openings in the substrate, an extension of the layers of filter material into the tapered edge of the openings in the substrate, the extension extends at least to the second side of the openings in the substrate, and a particulate trapping adhesive attached to the first side of each layer of the filter material.

Abstract: The present invention provides a filter medium reducing an increase in pressure drop while in use even in an environment where ultrafine particles form a large proportion of the particles to be collected. The filter medium includes a porous polytetrafluoroethylene (PTFE) membrane, an air-permeable supporting member and a web layer made of polymeric fibers formed by electrospinning (charge induction spinning, electrostatic spinning). The filter medium of the present invention may include an air-permeable adhesive layer adjacent to the web layer.

Abstract: A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

Abstract: A filter apparatus for improving gas temperature stability while maintaining a high impurity removal capacity. The filter apparatus includes a filter for removing impurities from a gas and a temperature adjuster for adjusting the temperature of the gas to a predetermined temperature. The filter apparatus further includes a humidity detector, arranged at the upstream side of the filter, for adjusting the humidity of the gas before the gas passes through the filter.

Abstract: A filter system includes a set of modules, each module including screen assemblies and filter media sandwiched between the screen assemblies. A plurality of control assemblies are associated with each of the modules. Each of the control assemblies is in fluid communication with a corresponding module to control flow through the corresponding module. The control assemblies selectively control fluid in each of the modules between at least one of a forward flow through the screen assemblies to treat an influent flow, a bypass flow to bypass at least one of the modules, and a reverse flow to backwash a given filter media. A method of filtering influent includes providing an influent flow to a set of modules, each module including screen assemblies and filter media sandwiched between the screen assemblies. The influent is filtered by directing the influent through the set of modules. A given module is bypassed when the given module becomes occluded.

Abstract: An integral fuel cartridge and filter apparatus includes a fuel cartridge, a filter housing coupled to the fuel cartridge, and a filter coupled to the filter housing.

Abstract: An apparatus and method for gas/liquid separation on an array of jets or streams of liquid is provided. Layers of substantially spherical aggregates of meshed material are provided to “quiet” high-velocity liquid flow with entrained gas to provide a uniform flow at moderate or low velocity from which the gas has been substantially separated from the liquid.

Abstract: A pipe trap comprising a body, a disc filter, a pipe and a plurality of mesh filter suitable for filtering gases is provided. The pipe trap body has a gas inlet and a gas outlet. The disc filter and the mesh filters are enclosed inside the pipe trap body. One end of the pipe connects with the disc filter and the other end of the pipe connects with the gas outlet. The mesh filters are enclosed inside the pipe. Using a multi-stage filtering method, liquid matter separates out first and then gaseous particles are filtered according to the particle size so that the pipe trap has a high filtering efficiency.

Abstract: Converting machines give rise to polluted air which must be removed with the aid of fans and filters. The invention aims at removal of the polluted air in such a way that the servicing interval is greatly extended by the use of a filter unit having a number of part-filters arranged one after the other and formed of pleated fiber mats, the various mats having different filtering properties.

Abstract: A method for cleaning a filter having Z-media includes providing a filter having Z-media and cleaning the media construction by directing a pulse of compressed gas into the media construction through the downstream flow face. Filter elements useable with such methods include elements made of Z-media. An example system utilizing the method includes a gas turbine air intake system.

Abstract: A filter element, and filter apparatus, include a filter pack, a seal member, and a seal support frame operatively connecting the seal member to the filter pack. The seal support frame includes an annular extension, which is preferably canted at an oblique angle to a longitudinal axis, for supporting the seal member. The seal support frame also preferably includes a first end thereof including the annular extension, and a second end thereof spaced from the first end thereof along the longitudinal axis, with the first and second ends of the seal support frame joined by a hub of the outer peripheral sidewall of the seal support frame to define a cavity within the seal support frame for receiving the filter pack. The first and second ends of the seal support frame, and the filter pack are preferably joined and sealed to one another by a single bead of adhesive.

Abstract: An operating room filter system connectable to a surgical body gas evacuator, such as a trocar, that includes a carbon monoxide filter media that removes carbon monoxide from a surgical waste gas. In addition, the inclusion of further filter media upstream of the carbon monoxide filter media inhibits the saturation of the carbon monoxide filter media to thereby provide an extended life to the filtration system.

Abstract: A structure and method of removing semi-rigid debris and demisting gas for use primarily in surface maintenance or conditioning machines, Demisting is accomplished by, a combination techniques including rapid pressure reduction and removal of semi rigid debris is accomplished by forcing the debris through a path with curvatures to great for the debris to follow.

Abstract: A degassing apparatus for use with a polymerisation reactor is disclosed. Slurry from the reactor is discharged into a flask tank (3) in which monomers or dilluent vaporise to form a gas. Filler units (9, 10) are provided at the upper part of the flash tank (3). They may be selectively connected to the flash tank by valves (11, 12). No cyclone etc. is provided between the flash tank and the filter (9, 10) and these particles may then fall back into the flash tank (3). The filters may be separately isolated for cleaning or replacement.

Abstract: A dirt filtering apparatus for a vacuum cleaner is disclosed. The dirt filtering apparatus includes a lid member having an exit opening defined therethrough, a sealing arrangement around the periphery of the lid member and adapted to engage a sidewall of a removable dirt cup, and a removable filter attached to the lid member in a covering relationship to the exit opening. The dirt filtering apparatus further includes a removable screen support attached to the lid member and surrounding the filter member. The dirt filtering apparatus yet further includes a horizontal opening defined through the screen support and a screen element covering the horizontal opening. A method of operating a filter assembly is also disclosed.

Abstract: The collecting filter can capture and collect various chlorinated organic compounds in both particulate form and gaseous form contained in a fluid at the same time, and is easy to extract the collected chlorinated organic compounds therefrom. This collecting filter 7 is provided with a fluid-permeable molded body containing fibers and an inorganic binder for binding the fibers to one another, and a hydrophobic material having higher hydrophobicity than that of the fibers and the inorganic binder, which is retained in the molded body. Various chlorinated organic compounds such as dioxins in both particulate form and gaseous form contained in the sample gas are captured and collected upon passage through the collecting filter 7.

Abstract: An apparatus for cleaning air, and a method for cleaning air using the apparatus, includes a housing including an air inlet through which air to be cleaned flows into the housing and an air outlet through which air that has been cleaned is exhausted from the housing, the housing isolating an interior thereof from external surroundings. A first filtering unit is disposed adjacent to the air inlet and includes a plurality of first filters for removing a first group of contaminants from the air to be cleaned. Each of the plurality of first filters is disposed substantially parallel to each other. A fan for drawing the air to be cleaned into the housing from the external surroundings is disposed in the housing.

Abstract: A filter arrangement includes a first filter element having opposite first and second ends; an axial length between the first and second ends; and a plurality of flutes. Each of the flutes has a first end portion adjacent to the first filter element first end, and a second end portion adjacent to the first filter element second end. Selected ones of the flutes are open at the first end portion and closed at the second end portion; and selected ones of the flutes are closed at the first end portion and open at the second end portion. A sleeve member secured to and circumscribing the first filter element. The sleeve member is oriented relative the first filter element to extend at least 30% of the axial length of the first filter element. A seal member pressure flange at least partially circumscribes the sleeve member. The filter arrangement is particularly useful for gas turbine systems. Methods for operating and servicing filter arrangements preferably utilize constructions herein.

Abstract: A method and mobile system for cleaning dirty gas from a newly stimulated gas well. The entire system is supported on a trailer or other mobile support so that it can be driven from well site to well site for short-term, post-stimulation use only. The system comprises a gas separator, such as a membrane separator. The system also includes a pretreatment assembly for preparing the gas for the gas separator. The pretreatment assembly may include separators, a heater, a guard vessel and a polishing filter. A chiller or heat exchanger cools the treated gas to a marketable temperature. A generator and a hydraulics plant provide power to the system. Each mobile system will be designed to treat gases with widely different operating conditions varying from well to well.

Abstract: A filter assembly for a removable dirt separation system is disclosed. The filter assembly includes a wall support attached to a wall of the dirt separation system and a screen panel having a number of screen elements. The filter assembly further includes a filter element which is selectively releasable from the screen panel. The screen panel and filter element can be selectively secured to the wall support. A fine particle separation chamber is at least partially defined by the screen elements and the filter element. A portion of the walls of a dirt cup within the dirt separation system is formed by the filter assembly. A method of operating a filter assembly for a removable dirt separation system is also disclosed.

Abstract: Filtration media are disclosed for use in high efficiency air filters for filtering particulate matter in air. The media make use of at least one layer of fibers having a diameter less than 1000 nanometers sandwiched between two scrim layers to achieve high efficiency particulate air (HEPA) filtration performance at relatively low pressure drops.

Abstract: A filter assembly is disclosed for use in connection with the filtration of products transported via pipelines, including high pressure gas pipelines. The disclosed filter assembly is comprised of a plurality of filter modules, a series of valves, inlet and outlet ports, connective piping, and spool pieces. The filter assembly will temporarily redirect flow from the pipeline, through one or more filter assemblies, and back into the original pipeline a short distance downstream from the original takeout point. If flanged connections are not readily available for a particular section of pipeline, the filter assembly can be connected to virtually any section of pipe through “hot tapping” technology, which allows a valve to be placed on an active and pressurized section of pipeline.

Abstract: An arrangement for separating a hydrophobic liquid phase from a gaseous stream includes a coalescer filter, a housing, a gas flow direction arrangement, and a liquid collection arrangement. The coalescer filter includes a non-woven media of fibers. The housing includes an interior having a gas flow inlet and a gas flow outlet. The liquid collection arrangement is positioned within the housing construction and is oriented for receiving liquid collected from the coalescer filter and drained therefrom.

Abstract: The present invention is a system and method for improving the useful life of sorbent beds, such as activated carbon filter beds. It is known that breakthrough in carbon filter beds first occurs at the low gas velocity regions of the filter bed, i.e., at the filter's edges. A recirculation jacket filter system diverts already filtered air from the downstream side of the filter bed toward the peripheral region of the upstream side of the filter bed so that contaminants near the filter's edges are reduced and filter life is improved.

Abstract: A deep gradient-density filter device capable of effectively filtering a fluid containing a distribution of particles in the range of approximately 25 microns to approximately 0.2 micron at a fluid velocity of at least approximately 100 cm/hr and an initial hydraulic permeability of greater than approximately 10 cm/hr/psi. The deep gradient-density filter device includes several layers of filtration material, each having specific predetermined particle retention properties. In one product embodiment, the deep gradient-density filter device uses “loose” fibrillated cellulose fiber material as a primary filter element. In a method aspect, the deep gradient-density filter device is used for either the secondary clarification of industrial-scale volumes of cultured or fermented protein-containing biopharmaceutical fluids or the primary clarification of pilot-scale volumes.

Abstract: An adapter for use with a low volume PUF sampler is described. The adapter is affixed over the open end of a PUF (polyurethane foam) sample cartridge. Sample tubing is affixed to an aperture in the adapter, and the free end of the sample tubing is then positioned at a desired sample location such as within an aircraft interior. As a vacuum is applied to the PUF cartridge, the adapter allows air collected at the sample point to pass through the tubing and through the interior of the PUF cartridge while preventing air surrounding the PUF cartridge from being drawn into the PUF cartridge except through the sample tubing. In this manner the sample point of a desired air sample can be selected at a point remote from the PUF cartridge. Additionally, use of multiple PUF cartridges and adapters allows the simultaneous collection of separate air samples.

Abstract: A filter system for filtering intake air for a combustion engine, in particular an air filter for a commercial vehicle, having a tubular housing, an inlet situated in the housing through which unfiltered air to be cleaned can be supplied, an outlet situated in the housing through which cleaned air can be discharged, an arrangement of filters situated in the housing between the inlet and outlet which form a seal such that air from the inlet must flow through the filter arrangement to reach the outlet, the housing having an opening for replacement of the filter which can be closed and sealed by a housing cover, and in which at least one prefilter, one main filter and one secondary filter are situated in the housing in axial succession one after the other in the direction of air flow through the filter system.

Abstract: The invention refers to a composite filter for filtering a stream of ambient air including at least one non-prebonded upstream tier and one non-prebonded downstream tier, wherein the ratio of absolute pore volume of upstream tier to downstream tier RAPV>2, and the absolute projected fiber coverage of upstream tier and of downstream tier APFC>95%. Further, the invention refers to a method of making such a composite filter including the steps of (a) laying down a filtration material onto a support to form the upstream non-prebonded tier, (b) depositing onto the upstream tier the downstream non-prebonded tier, and (c) bonding the tiers to form a composite filter having a unitary stratified structure.

Abstract: Filter devices, suitable for rendering pathogenic microorganisms non-viable and capable of regeneration to serve as filter devices for applications such as diesel engines where combustible particulates are trapped, include at least one porous filter element which is capable of electrically resistive heating to a temperature such that pathogens are rendered non-viable, and/or to a regeneration temperature such that combustible particulates are destroyed.

Abstract: Filters for removing particulate and gaseous organic and inorganic materials from a fluid stream are disclosed. The filters may contain a polymer matrix and optional sequestering agents. Methods of making filters are also disclosed. Methods of using filters to remove one or more materials from a fluid stream, such as an air stream, are also disclosed.

Abstract: An improved cartridge, typically in cylindrical or panel form that can be used in a dry or wet/dry vacuum cleaner. The cartridge is cleanable using a stream of service water, or by rapping on a solid object, or by using a compressed gas stream, but can provide exceptional filtering properties even for submicron particulate in the household or industrial environment. The cartridge has a combination of nanofiber filtration layer on a substrate. The nanofiber and substrate are engineered to obtain a maximum efficiency at reasonable pressure drop and permeability. The improved cartridge constitutes at least a substrate material and at least a layer including a non-woven, fine fiber separation layer.

Abstract: A filter arrangement includes a first filter element having opposite first and second ends; an axial length between the first and second ends; and a plurality of flutes. Each of the flutes has a first end portion adjacent to the first filter element first end, and a second end portion adjacent to the first filter element second end. Selected ones of the flutes are open at the first end potion and closed at the second end portion; and selected ones of the flutes are closed at the first end portion and open at the second end portion. A sleeve member secured to and circumscribing the first filter element. The sleeve member is oriented relative the first filter element to extend at least 30% of the axial length of the first filter element. A seal member pressure flange at least partially circumscribes the sleeve member. The filter arrangement is particularly useful for gas turbine systems. Methods for operating and servicing filter arrangements preferably utilize constructions herein.

Abstract: The present invention provides a combination filter for filtering fluids comprising a flow channel particulate filtration media having a first face and a second face and a gas adsorbing filtration media. The flow channel particulate filtration media comprises a plurality of flow channels directed in flow direction and defined by inner surfaces. The flow channels having inlet openings through the first face and outlet openings through the second face of the flow channel particulate filtration media. The inner surfaces of said flow channels at least in part are provided with structures protruding therefrom and forming or extending into the flow channels or an electrical charge or a combination of both. The said gas adsorbing filtration media comprises a pad having a first face and a second face and width and length dimensions orthogonal with respect to each other and each individually to the flow direction and having a thickness dimension in flow direction.

Abstract: Portable, rapidly deployable filter unit for use in air filtering methods providing high efficiency filtration of airborne toxins. The filter unit includes a fan section and a filter section that are releasably attachable at their respective lateral ends permitting the filter unit to be reconfigurable to properly handle a variety of threat scenarios involving protecting the occupant(s) and equipment in an enclosure against an airborne release of toxic chemical, biological, or radiological agents that threaten to contaminate the air supply, or, alternatively, for decontaminating the air of an isolation room occupied by contaminated or contagiously ill persons or materials and protecting the occupants or equipment located outside the isolation room.

Abstract: A filter cleaner for wet/dry vacuum is provided for effectively cleaning filter cartridges employed for use in a class of vacuum cleaners commonly referred to as “wet/dry vacs.” The filter cleaner apparatus includes a cylindrical catch tank supported by a base. The catch tank supports an attachable circular lid. A motor cover, which is disposed atop the circular lid, is mounted with a handle. Housed within catch tank is an electric motor which spinably drives an upper filter plate via a rotatable shaft. A lower filter plate assembly housed within catch tank includes a rotatable lower filter plate being spring-biased in an upward manner. The lower filter plate assembly further includes a debris directional funnel which directs debris to a removable collection tray.

Abstract: The invention describes a multi-layer filter structure and the use of a multi-layer filter structure for the dust removal from gases, wherein a coarse dust filter layer, a fine dust filter layer, and a support layer are disposed behind one another in the direction from the inflow side to the outflow side, and which is designed such that the fiber diameter distribution within the coarse dust filter layer and fine dust filter layer has a gradient, and that the fiber diameters of the coarse dust filter layer and fine dust filter layer continually decrease from the inflow side to the outflow side. This multi-layer filter structure may be used in a filter cassette for industrial dust removal, as well as in a stationary or mobile home dust cleaning device.

Abstract: An oil separator for oil-flooded rotary vane vacuum pumps has a filter housing (10) and a plurality of filter cartridges (14) disposed therein through which the pumping medium flows. The filter cartridges (14) are each inserted through a respective opening (16) in an outer housing wall (12) of the filter housing (10) and are secured to the housing wall (12) so as to be detachable and tight with respect to media.

Abstract: A filter arrangement includes a first filter element having opposite first and second ends; an axial length between the first and second ends; and a plurality of flutes. Each of the flutes has a first end portion adjacent to the first filter element first end, and a second end portion adjacent to the first filter element second end. Selected ones of the flutes are open at the first end potion and closed at the second end portion; and selected ones of the flutes are closed at the first end portion and open at the second end portion. A sleeve member secured to and circumscribing the first filter element. The sleeve member is oriented relative the first filter element to extend at least 30% of the axial length of the first filter element. A seal member pressure flange at least partially circumscribes the sleeve member. The filter arrangement is particularly useful for gas turbine systems. Methods for operating and servicing filter arrangements preferably utilize constructions herein.

Abstract: A method and mobile system for cleaning dirty gas from a newly stimulated gas well. The entire system is supported on a trailer or other mobile support so that it can be driven from well site to well site for short-term, post-stimulation use only. The system comprises a gas separator, such as a membrane separator. The system also includes a pretreatment assembly for preparing the gas for the gas separator. The pretreatment assembly may include separators, a heater, a guard vessel and a polishing filter. A chiller or heat exchanger cools the treated gas to a marketable temperature. A generator and a hydraulics plant provide power to the system. Each mobile system will be designed to treat gases with widely different operating conditions varying from well to well.

Abstract: An air purifier includes a main body defining an air passage therein to allow sucked air to pass therethrough prior to being discharged, and a first filter installed in the main body to be switched between a closed state and an open state. The first filter removes contaminants from the sucked air in the closed state, and allows the sucked air to pass through the air passage in the open state. The air purifier may include a main body to suck and discharge air, with a bypass passage formed in the main body so that the bypass passage is opened or closed by a door, and a first filter installed in the main body. The sucked air passes through the first filter prior to being discharged when the door is closed, and passes through the bypass passage prior to being discharged when the door is opened.