Abstract: A Diesel Particulate Filter (DPF) assembly configured to be incorporated in the exhaust gas stream, the DPF assembly comprising: Quartz/Composite ceramic mixture disposed as filter elements, mechanical support components and optional electrical soot removal solutions including electrical, di-electrical and microwave solutions.

Abstract: A mold sensor include a housing that defines an enclosed chamber in which a nutrient-treated substrate is positioned. The mold sensor includes a substrate advancement mechanism that is configured to selectively move the substrate to expose a surface of the substrate within the chamber. The mold sensor includes a sensor configured to detect mold growth on the substrate within the chamber.

Abstract: A method for detecting water in diesel fuel filters is disclosed by arranging a first electrode and a second electrode in a medium located in the diesel fuel filter, forming an equivalent parallel RC circuit; applying an injection phase (A), during which a closed first switch and an open second switch are arranged such that a working electric current is injected in the first electrode, and the second electrode is connected to ground, delivering an electric charge; applying a relaxation phase (B), during which the open first switch and the closed second switch are arranged such that both the first electrode and the second electrode are connected to ground, the electric charge being dissipated through the medium; evaluating the voltage according to a capacitive component of the equivalent parallel RC circuit; and determining the medium.

Abstract: An adsorbed natural gas storing tank is provided. The adsorbed natural gas storing tank includes a tank body that has an upper plate and a lower plate coupled to define an inner space provided with an adsorbent material. The tank body includes an opening that extends through the upper and lower plates. A central plate is inserted in the opening to seal one side of the tank body. Additionally, the central plate has a plurality of discharge apertures formed along a circumferential wall thereof to discharge natural gas reacted with the adsorbent material and has a mounting region therein. A filter assembly is inserted in the mounting region, is fastened to the central plate, filters natural gas passing through the discharge apertures, and is equipped with a control valve for adjusting natural gas discharge.

Abstract: A liquid cleaning system rests on a surface having a non-porous material covering and a drain. A lower plate layer and an upper plate layer each have runners arranged in a grid. The lower plate layer rests upon the surface and the upper plate layer rests upon the lower plate layer offset at an angle with respect to the grid of the lower plate layer. An upper layer covers the upper plate layer and has a plurality of holes for the passage of fluids into the liquid cleaning system. As liquid enters the liquid cleaning system through the holes, the liquid traverses the grid of the lower plate layer and the grid of the upper plate layer flowing towards the drain, and contaminants within the liquid collect within the grid of the lower plate layer and the grid of the upper plate layer.

Abstract: A paint booth or paint booth system is presented having an upper and lower portion containing a flood plane panel located at the lower portion of the paint spray booth. An annular region is formed within the flood plane panel for receipt of a metal mesh filter removably fixed within the annular region and at least partially above the flood plane panel, for filtering of paint spray booth contents. The paint spray booth may also contain a perforated plate fixed over the filter for regulating the flow of air and bulk fluid through the filter.

Abstract: The exhaust gas treatment apparatus has a sealed vessel which is vertically partitioned into two spaces by a partition. A portion of the sealed vessel lower than the partition is an absorbing liquid storage portion, and a portion of the sealed vessel upper than the partition is an exhaust gas introducing portion. The partition is provided with a large number of sparger pipes so that the sparger pipes reach inside an absorbing liquid stored in the absorbing liquid storage portion. The partition is provided with a single gas riser in communication with a space upper than the absorbing liquid in the absorbing liquid storage portion. An upper end of the gas riser passes through a top plate portion of the sealed vessel and protrudes upward.

Abstract: A filter element for the filtration of the incoming cabin air of vehicles is disclosed. The filter element can be readily regenerated and reused in a dust-loaded environment. The filer element includes a main body formed from at least one filter medium. The main body has an inflow side and an outflow side. The filter element is used as a regenerable filter element for the filtration of the incoming cabin air in a vehicle which is subjected to elevated dust loading. A coating of nanofibres and/or a diaphragm is arranged on the inflow side of the main body.

Abstract: An emissions cleaning module includes a first conduit including an inlet and an outlet and containing a particulate filter; a second conduit including an inlet and an outlet; and an end coupling fluidly connecting the outlet of the first conduit to the inlet of the second conduit. The end coupling is provided with a cleaning port including a cover which closes an aperture in the end coupling. Providing the cleaning port in the end coupling fluidly connecting the outlet of the first conduit to the inlet of the second allows for improved access and cleaning of the emissions cleaning module.

Abstract: A method for removing residual filter cakes that remain adhered to a filter after typical particulate removal methodologies have been employed, such as pulse-jet filter element cleaning, for all cleanable filters used for air pollution control, dust control, or powder control.

Abstract: A control apparatus for an internal combustion engine detects an amount of particulate matter contained in an exhaust gas in an exhaust passage, according to an electrical property across electrodes of a particulate matter sensor disposed in the exhaust passage of the internal combustion engine. The term “electrical property” here refers to a property that changes with the amount of particulate matter deposited, for example, a current value of when a predetermined voltage is applied. After the internal combustion engine is started and detection of the amount of the particulate matter is completed, an element section of the particulate matter sensor is set to a predetermined temperature range. The particulate matter deposited on the element section is thereby burned and removed. The control apparatus maintains the element section in the predetermined temperature range after burning and removing the particulate matter until the internal combustion engine stops.

Abstract: A filter assembly and method of operating the filter assembly includes a hinge attached to a first end of a filter while a lifting mechanism is attached to a second end of the filter. The lifting mechanism lifts and releases the second end of the filter causing an impact such that dust and debris caught in the filter is dislodged.

Abstract: A control apparatus for an internal combustion engine detects an amount of particulate matter contained in an exhaust gas in an exhaust passage, according to an electrical property across electrodes of a particulate matter sensor disposed in the exhaust passage of the internal combustion engine. The term “electrical property” here refers to a property that changes with the amount of particulate matter deposited, for example, a current value of when a predetermined voltage is applied. After the internal combustion engine is started and detection of the amount of the particulate matter is completed, an element section of the particulate matter sensor is set to a predetermined temperature range. The particulate matter deposited on the element section is thereby burned and removed. The control apparatus maintains the element section in the predetermined temperature range after burning and removing the particulate matter until the internal combustion engine stops.

Abstract: A system and method of cleaning and scrubbing contaminants, including sulfides, from an unclean or raw gas includes one or more containers, each of which include a gas permeable receptacle or bag containing an appropriate gas scrubbing medium for removing the contaminants from the gas stream. A gas extraction device is adapted via inserted into the gas scrubbing medium with the gas permeable receptacle wherein the gas extraction device is connected to at least one gas outlet port in the container. A series of containers can be used wherein the containers are connected sequentially to remove the gas. A system for bypassing one of the plurality of containers in order to clean out the container while the gas cleaning mechanism is still in operation is also described.

Abstract: A control apparatus for an internal combustion engine detects an amount of particulate matter contained in an exhaust gas in an exhaust passage, according to an electrical property across electrodes of a particulate matter sensor disposed in the exhaust passage of the internal combustion engine. The term “electrical property” here refers to a property that changes with the amount of particulate matter deposited, for example, a current value of when a predetermined voltage is applied. After the internal combustion engine is started and detection of the amount of the particulate matter is completed, an element section of the particulate matter sensor is set to a predetermined temperature range. The particulate matter deposited on the element section is thereby burned and removed. The control apparatus maintains the element section in the predetermined temperature range after burning and removing the particulate matter until the internal combustion engine stops.

Abstract: A method and an arrangement for cleaning a particulate filter in a vehicle provided with an internal combustion engine is provided. The particulate filter is mounted in an operative position inside an exhaust muffler under normal operation of the engine. The method involves performing a cleaning process including disassembling and removing the particulate filter from a first end of the muffler; reversing and reassembling the particulate filter a cleaning position at the first end of the muffler; starting and operating the engine by controlling the engine speed according to a predefined cycle until a predetermined condition is fulfilled; and stopping the engine and returning the particulate filter to its operative position inside the exhaust muffler.

Abstract: A partial wall-flow filter, having a honeycomb structure including an inlet end, an outlet end, and parallel channels disposed and configured to flow fluid from the inlet end to the outlet end. The channels are defined by a plurality of intersecting porous walls. The partial wall-flow filter has a filtration region of channels plugged at the outlet end and a bypass region of unplugged channels. An N/S ratio of the filter material is less than or equal to about 0.5, less than or equal to about 0.3, less than or equal to about 0.1, or even 0, where N is a pressure drop difference induced by deep bed soot and S is a pressure drop change from 0 grams per liter (g/l) to about 5 g/l for a conditioned curve induced by cake bed soot, where N and S are measured on a full wall-flow filter of the filter material.

Abstract: A process for the combustion of a carbon-containing fuel, wherein the flue gases are filtered so as to achieve a solid particle concentration of less than 1 mg/m3 before compression, purification and sequestration or transport is presented.

Abstract: A system and method for controlling the operation of a particulate filter is disclosed. The objective of this control system is to manipulate the properties and spatial distribution of contaminant material accumulated in filters to reduce filter pressure drop and associated deleterious impacts of the contaminant material on filter performance.

Abstract: Embodiments of the invention generally provide an apparatus and method for decontaminating tubing. The invention is particularly suitable for decontaminating tubing in a test system used for certifying a filter in a containment system. In one embodiment, a test system for a containment system is provide that includes a sample system including equipment adapted for testing a filter disposed in a containment system utilizing samples obtained from a downstream sample port and a upstream sample port of the containment system, and a device for reversing a flow within the sample system. In another aspect of the invention, a method for decontaminating tubing is provided. In another embodiment, the method includes flowing a sterilization agent through tubing in a first direction and flowing the sterilization agent through tubing in a second direction.

Abstract: Related is a method for regeneration of a particulate filter 6 wherein manual regeneration of the particulate filter 6 started with a vehicle being stopped causes an exhaust brake 14 to throttle an exhaust passage. This increases an engine load and a fuel injection amount to elevate in temperature an exhaust gas 3; then, fuel addition is started by post injection with a fuel injection device 10, and the particulate filter 6 is regenerated by heat of an oxidation reaction of the added fuel on an oxidation catalyst 5 . After the starting of the manual regeneration, whether a fuel injection amount exceeds a reference value or not is judged. Only if the judgment is affirmative, throttling of the exhaust passage by the exhaust brake 14 is released provided exhaust temperature exceeds a reference temperature on an entry side of the particulate filter 6.

Abstract: Ignition system for reliable starting and maintaining regeneration process of Diesel particulate filer wherein the said ignition system is composed of a diesel particulate filter inside the exhaust pipe, fuel burner beside the exhaust pipe, ignition system for fuel burner, a tube for supplying the fuel, a tube for air intake, spark plug with a special arrangement of spark gap, battery as electric energy supply, an engine control unit and high voltage screened interconnection cable whereas the ignition system comprises spark plug (5) and glow plug (6) with the air gap (11) formed by central electrode (7) of spark plug (5) and glowing tip (8) of glow plug (6), grounded by fixing point (10), whereas spark is formed in mentioned spark gap (11).

Abstract: A coalescing filter includes a coalescing filter medium having an entrance face and an exit face and a surface energy, the coalescing filter also having a drainage channel in the coalescing filter medium, the drainage channel being a woven or non-woven fiber construct having a pore size greater than the pore size of said coalescing filter medium and having a surface energy that is lower than the surface energy of the coalescing filter medium, the drainage channel extending at a downward angle relative to the direction from the entrance face to the exit face.

Abstract: A method of using a modular International Organization for Standardization (ISO) filter house for filtering process fluids is provided. The filter house includes a self-contained rectangular cuboid enclosure having the outside dimension of a standard, transportable ISO shipping container. The filter house has apertures for fluid flow inlet and fluid flow outlet, and a filter element for removing impurities from the fluid flow. The method includes creating one standard filter house design to be used in any multiple to meet various flow requirements. The method further includes creating a common fluid connection between the filter houses and process equipment so that the filter houses operate in parallel. A kit of modular components for filtration of a fluid is also provided. The kit includes an external structure of an ISO shipping container, vanes to direct fluid flow, and a filter element.

Abstract: This invention proposes a method of removing pollutants from high temperature gasses prior to their introduction in to a heat exchanger of a steam generating boiler within a power generation system. The method comprises placing a filter system (100) in a hot gas flow path upstream of a waste-heat boiler. The filter system comprising at least two banks of substantially hollow elongate filters (110), each of which filters particles from the gas flow as it flows from an external surface thereof to an internal surface thereof. Valves (104, 106) enable each bank of filters to be isolated from the hot gas flow path. The method included periodically isolating at least one bank of filters while passing hot gasses through at least another of the banks of filters, and cleaning the isolated bank of filters. After cleaning the filters (110) lime is injected into the flow path so that it coats the outer surface of the filters (110) to produce a loose lime coating thereon.

Abstract: Methods for generating and applying coatings to filters with porous material in order to reduce large pressure drop increases as material accumulates in a filter, as well as the filter exhibiting reduced and/or more uniform pressure drop. The filter can be a diesel particulate trap for removing particulate matter such as soot from the exhaust of a diesel engine. Porous material such as ash is loaded on the surface of the substrate or filter walls, such as by coating, depositing, distributing or layering the porous material along the channel walls of the filter in an amount effective for minimizing or preventing depth filtration during use of the filter. Efficient filtration at acceptable flow rates is achieved.

Abstract: A method for recovering and treating hydrocarbon fluids using a hydraulic fracturing process wherein a fluid stream containing liquid or gaseous hydrocarbon species or both, produced water, suspended solids, and dissolved contaminants is recovered from a well. and hydrocarbon species are separated from the fluid stream to produce a second fluid stream comprising liquid water, which is then directed to a filter medium and essentially all of the second fluid stream passes through the medium to produce a permeate stream and a filter cake, and the filter cake is separated from the medium and disposed of separately.

Abstract: Various systems and methods are provided for supplying heat to a passenger compartment during a filter regeneration event. In one example, a first phase of a filter regeneration event is initiated for a filter in an internal combustion engine based on one or more parameters, with heat produced by the engine then supplied to a heater core during the first phase, and the first phase extended if heating is requested. The engine may be operated at reduced efficiency during the filter regeneration event, and in some embodiments, the method may further include injecting an additional amount of fuel during a second phase of the filter regeneration event after the first phase ends to cause soot combustion in the filter.

Abstract: A device and method for influencing exhaust gas flow downstream of a turbocharger turbine and upstream of after treatment components prevents doser tip fouling by using a passive exhaust flow control surface comprising ridges protruding into the exhaust gas flow conduit. The ridges are disposed parallel to each other, and perpendicular to the direction of gas flow. In one embodiment, a funnel is disposed in the conduit, downstream of the ridges, to further direct the exhaust gas flow more precisely towards a HC doser tip.

Abstract: An exhaust gas purification apparatus for an engine is provided with a filter arranged in an exhaust passage of the engine, and a regeneration control unit for regenerating the filter by burning the particulate matters accumulated in the filter. The control unit may include an over-accumulation state determination unit and a switch. The over-accumulation state determination unit determines over-accumulation of the particulate filter in the filter when the particulate matter is over-accumulated in the filter. The switch switches a regeneration temperature for regenerating the filter between a first regeneration temperature at which a normal regeneration is performed and a second regeneration temperature which is lower than the first regeneration temperature. The control unit is connectable to a command unit when the particular matter is over-accumulated in the filter, so that the switch is forcibly operated toward the second regeneration temperature.

Abstract: A headgear assembly for a baghouse filter can include a headgear configured to allow for concentric arrangement of first and second filters coupled thereto, where at least one of the first filter, second filter, and headgear can include an opening through which accumulated particulate from the second filter can pass. The headgear assembly can also include a cleaning assembly configured to facilitate cleaning of at least one of the first and second filters. Methods of facilitating on-line cleaning of a baghouse filter are also described wherein an exhaust stream is passed through concentrically arranged first and second filters to produce a filtered stream. At least one of the first and second filters can be cleaned using a cleaning assembly to remove accumulated particulate, which can pass through an opening in at least one of the first filter, the second filter, and the headgear.

Abstract: A system for a vehicle includes a regeneration module and a disconnection indication module. The regeneration module indicates when a regeneration of a particulate filter is complete. The disconnection indication module receives a pressure difference across the particulate filter measured using delta pressure sensor. The delta pressure sensor generates the pressure difference based on first and second pressures upstream and downstream of the particulate filter applied to the delta pressure sensor using upstream and downstream pressure lines, respectively. In response to an indication that the regeneration of the particulate filter is complete, the disconnection indication module selectively indicates that the downstream pressure line is disconnected based on a comparison of the pressure difference and a predetermined pressure.

Abstract: A system comprises a particulate matter (PM) filter comprising an inlet for receiving exhaust gas. A zoned heater is arranged in the inlet and comprises a resistive heater comprising N zones, where N is an integer greater than one. Each of the N zones comprises M sub-zones, where M is an integer greater than one. A control module selectively activates one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones and deactivates others of the N zones.

Abstract: An exhaust treatment system for machine is disclosed that includes a burner body having an inlet for receiving a flow of exhaust, an outlet for the exhaust flow to exit, an opening and a receiving mount disposed around the opening. A fuel injector head is mounted over the opening in any one of a plurality of angular positions relative to the body. The burner body includes a plurality of mounting pads extending at least partially and circumferentially around the burner body for coupling a support bracket to the burner body in any one of a plurality of positions relative to the burner body. The support bracket may be used to couple the burner to a fixture device such as a cradle for supporting other exhaust treatment system components.

Abstract: A filter assembly including a rectangular inlet frame having a rectangular inlet opening to receive a primary filter and optional a prefilter. The filter assembly may include a rectangular outlet frame and a housing body that is collapsible to have a flattened shipping state and an erect state. The rectangular inlet frame may also be used as a housing by itself to support and house primary filters and prefilters. A gridwork including one or more grid dividers may be used in the rectangular inlet frame to provide 2 or more openings for receipt of filters.

Abstract: A method for removing residual filter cakes that remain adhered to a filter after typical particulate removal methodologies have been employed, such as pulse-jet filter element cleaning, for all cleanable filters used for air pollution control, dust control, or powder control.

Abstract: Systems and methods for processing high purity materials are disclosed. A unit operation processes a material stream, an operational parameter of the unit operation is monitored, and a standby unit is charged with pressurized gas to achieve system pressure. The material stream is diverted to the standby unit in response to the operational parameter of the unit operation registering a threshold value. Flow exiting the standby unit is first vented via an outlet, and then directed toward a point of use after the pressurized gas has been purged. The unit operation may then be serviced and subsequently brought back online. A second unit operation may process a second material stream simultaneously, and the second material stream may be periodically diverted to the standby unit in like manner, thus reducing line pressure variation. The disclosed method may be performed manually or implemented automatically through use of a controller.

Abstract: The present invention relates to a novel enclosure and air filtration design for use with robotic welding stations. It includes a novel frame design, novel air cleaning systems and systems for reducing the frequency of cleaning the air cleaning system.

Abstract: The present invention includes: a rolled filter stretched between first and second winding shafts and, unused part of the filter being wound around the second winding shaft; a brush provided between the first and the second winding shafts so as to come into contact with a surface of the filter; a feeding mechanism for driving the first and the second winding shafts to take up or rewind the filter; and a feeding control unit for controlling the feeding mechanism. When activating a renewing operation for feeding unused part of the filter from the second winding shaft, the feeding control unit controls the feeding mechanism such that once the filter is taken up by the first winding shaft by an take-up amount La, the filter is rewound by the second winding shaft by a rewind amount Lb, and La and Lb satisfy a relationship La?Lb.

Abstract: A system includes a particulate matter (PM) filter with an upstream end for receiving exhaust gas, a downstream end and zones. The system also includes a heating element. A control module selectively activates the heating element to inductively heat one of the zones.

Abstract: A method of cleaning a vehicle exhaust system filter (1), the filter (1) having a first end (11) and a second end (10) and comprising a plurality of elongate channels (6) containing debris (19) to be removed, comprises the steps of: (i) providing a chamber (14) having an outlet in fluid communication with the first end (11) of the filter (1); (ii) covering the second end (10) of the filter (1) to hinder fluid flow out of the second end of the filter; (iii) introducing a flow of liquid into the chamber (14); (iv) stopping the flow of liquid into the chamber (14) when the chamber and channels (6) of the filter are substantially filled with liquid; (v) introducing a pulse of compressed gas into the chamber (14), and (vi) uncovering the second end (11) of the filter (1) to allow the gas to force said debris (19) and liquid (17) out of the second end (10) of the filter (1). The invention also provides apparatus for use in the method.

Abstract: The present disclosure provides a method and apparatus for measuring ash deposit levels in a particulate filter comprising at least one cell. One or more indicator components is inserted into the at least one cell so as to lie upon any deposits contained therein. Radiation is emitted from a radiation source into the cell, and the position of the one or more indicator components is detected on the basis of the emitted radiation. The deposit level within the cell is then calculated on the basis of the position of the one or more indicator components.

Abstract: The present invention relates generally to a method for removing contaminants from a fluid stream and chemically upgrading the stream at the same time. More particularly, the invention relates to a catalytic moving bed filter for removing contaminants from a gas or vapor stream and to compositions comprising both moving bed filter materials and one or more catalysts intimately admixed therewith.

Abstract: In order to provide a device for separating wet paint overspray from a stream of crude gas containing overspray particles which includes at least two filter devices each of which has an inlet opening through which a partial stream of crude gas enters the respective filter device and each of which includes at least one filter element for separating the overspray from the partial stream of crude gas, which allows one to maintain the fluidity of the mixture including of filter aid material and wet paint overspray that has been cleansed from the filter elements in the filter aid material reservoirs in a simple and efficient manner, it is proposed that the device should comprise at least one reservoir for receiving material which has been cleansed from the filter elements of a plurality of filter devices and a mixing device for mechanically blending the cleansed material from a plurality of filter devices.

Abstract: The present invention relates to systems for regenerating a plugged diesel particulate filter (DPF) or catalyzed DPF. In certain embodiments, the system includes a fluid container and pulse valve, a heater, and a blower. Other embodiments include methods of regenerating a plugged DPF by directing a fluid at a first face of a DPF, redirecting the fluid at a second face of the DPF, and in some embodiment, heating the DPF.

Abstract: An apparatus for cleaning an air filter includes a body, a closed chamber formed within the body, a fluid dispersing member having a portion thereof mounted for rotation within the body and passing through the chamber, a plurality of orifices formed through the wall of the fluid dispersing member and an arrangement for rotating the fluid dispersing member. The arrangement either includes a combination of nozzles secured to the fluid dispersing member and positioned within the chamber and an irregular inner wall surface of the chamber capable of providing resistance to a fluid flow discharged into the chamber or fins disposed on the fluid dispersing member and a passageway through the body for directing fluid under pressure onto the fins. Fluid supplied under pressure to the fluid dispersing member exits through the plurality of orifices toward an inner surface of a air filter filtering medium causing contaminants to exit therefrom.

Abstract: A system comprises a particulate matter (PM) filter comprising an inlet for receiving exhaust gas. A zoned heater is arranged in the inlet and comprises a resistive heater comprising N zones, where N is an integer greater than one. Each of the N zones comprises M sub-zones, where M is an integer greater than one. A control module selectively activates one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones and deactivates others of the N zones.

Abstract: Embodiments of the invention generally provide an apparatus and method for decontaminating tubing. The invention is particularly suitable for decontaminating tubing in a test system used for certifying a filter in a containment system. In one embodiment, a test system for a containment system is provide that includes a sample system including equipment adapted for testing a filter disposed in a containment system utilizing samples obtained from a downstream sample port and a upstream sample port of the containment system, and a device for reversing a flow within the sample system. In another aspect of the invention, a method for decontaminating tubing is provided. In another embodiment, the method includes flowing a sterilization agent through tubing in a first direction and flowing the sterilization agent through tubing in a second direction.

Abstract: The present invention comprises a filter system for a computing device including a frame. In one embodiment, end members on the frame are biased toward each other so that, when the frame is mounted on a cabinet of the computing device, the opposing end members tightly fit around a portion of the cabinet, the filter fitting within the frame. In one embodiment, a majority of the filter is visible to the user, largely unobstructed by the frame. As a result, the status of the filter may be evident to the user, thereby facilitating its cleaning or replacement. In some embodiments, the user may clean the filter in place, and in some embodiments, the user may easily remove the frame with its opposing end members from the computer cabinet thereby permitting the filter to be easily cleaned or replaced.

Abstract: An apparatus and a method for filtering sectioning wastes of a microtome that are present in an air stream are described. The apparatus has an aspiration device with which sectioning waste can be aspirated from a blade region of the microtome with an air stream. A main filter and a prefilter are provided. A valve is provided for opening and closing an opening so that the air stream so that if desired an air stream can be directed through a filter insert in the prefilter for emptying the prefilter into the main filter. According to the method, an air stream that is used for aspirating sectioning waste from a blade region of the microtome is shut off immediately before emptying the prefilter.