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: An electrically enhanced air filtration system is disclosed which uses rear fiber charging is disclosed. In particular, a fibrous filter may be placed in an upstream position within the system with one or more ionization arrays positioned downstream or to the rear of the fibrous filter in terms of airflow direction. The fibrous filter may include a grounded side and fiber side with the grounded side being upstream of the fiber side. The ionization array may include a plurality of electrodes each extending unidirectionally toward the fibrous filter.

Abstract: An air cleaner for an enclosed electronic device such as an electronic slot machine, for use in areas that have a high level of air contamination from cigarette smoking such as casinos, includes an active field polarized media air cleaner or other filters for removing sub-micron particles, tars and/or volatile organic compounds (VOC's). In addition, a shared air cleaner for removing sub-micron particles, tars and/or VOCs is coupled to a plurality of enclosed electronic devices, such as a cluster of electronic slot machines.

Abstract: A gas sampling canister has an electrospray nozzle for creating an ionic fluid electrospray plume. A gas sample intake is positioned to provide a gas sample flowing through the ionic fluid electrospray plume. A cooled counter electrode is positioned to collect the electrospray plume such that selected chemicals in the gas sample are captured by ionic fluid accumulating on the cooled counter electrode. A system and method for sampling gas are also described.

Abstract: An air conditioning system includes an air flow pathway extending through a housing from an inlet to an outlet. Air conditioning apparatus is disposed in the airflow pathway between the inlet and the outlet conditioning an air stream passing through the air flow pathway from the inlet to the outlet. A modular electrically stimulated air filter apparatus is carried by opposed, parallel frameworks mounted in series in the air flow pathway between the inlet and the air conditioning apparatus filtering entrapping contaminants in the air stream flowing through the housing from the inlet to the outlet. The opposed parallel frameworks are mounted to opposed supports affixed to the housing.

Abstract: The subject matter of the invention are electrostatic filter method and electrostatic filter for separating particles from industrial waste gases, whereas an optimal electric charging or ionization in the ionization zone are performed in a high-voltage zone and its unchanged ducts with one high-voltage supply source to ensure the subsequent particle separation in the separation zone at sufficient field strength which requires minimal energy input.

Abstract: An air conditioning system includes an air flow pathway extending through a housing from an inlet to an outlet. Air conditioning apparatus is disposed in the airflow pathway between the inlet and the outlet conditioning an air stream passing through the air flow pathway from the inlet to the outlet. A modular electrically stimulated air filter apparatus is carried by opposed, parallel frameworks mounted in series in the air flow pathway between the inlet and the air conditioning apparatus filtering entrapping contaminants in the air stream flowing through the housing from the inlet to the outlet. The opposed parallel frameworks are mounted to opposed supports affixed to the housing.

Abstract: A reticle carrier for an Extreme Ultraviolet (EUV) reticle may include nested grids of electret fibers to provide active protection from contamination without a power supply. The reticle carrier may include in-line sensors for in-situ monitoring of contamination. Grids of electret fibers may also be used in an EUV pellicle.

Abstract: A method and apparatus using deep pleated filters to provide efficient and safe electrically enhanced filtering (EEF), with ultra low pressure drop, higher efficiency of particulate removal and higher dirt holding capacity over the life of the filter. An EEF may be constructed with a housing, with or without an internal air moving device such as a fan, a deeply pleated filter, preferably a V-pack filter with sets of downstream ground electrodes and charge transfer electrodes borne by the exterior surface of the filter packs that form the filtering element. An ionizer assembly that ionizes the gas and charges particles entering the deeply pleated filter and also transfers a charge to the charge transfer electrodes on the filter pack. A plate seals the gasket on the filtering element against the ionizing assembly. A high electrical potential is applied to charging elements in the ionizer and, in some embodiments, a fan or motor assembly.

Abstract: An air filtration system including a filter (4) for separation of particles and an ionizer (3) for ionization of the air. In use of the system, ionization of the air occurs before the air passes the filter (4). The filter (4) is made up of fibers of polypropylene mixed with acrylic.

Abstract: A multi-stage collector of the type used to collect particles from industrial gas. The collector can contain multiple narrow and wide zones formed by a plurality of parallel corrugated plates. Contained in the narrow zones can be elongated electrodes with sharp leading and/or trailing edges. These electrodes can provide a non-uniform electric field near their sharp edges leading to corona discharge. The corona discharge causes particulate matter in the gas flow to become charged. The region in narrow zones away from the sharp edges of the electrodes resembles a parallel plate capacitor with relatively uniform electric field. In this region, particles can be collected on the plates and on the electrode. Wide regions can contain barrier filters (bag filters) with conductive surfaces. The collector can also be used to clean inlet gas in gasification plants and to collect re-usable materials from a gas stream.

Abstract: A multilayer filter assembly for use inside an electronic enclosure, such as a hard disk drive enclosure containing a rotating disk, is disclosed. The filter assembly provides filtration of air entering the enclosure, as well as air circulating within the enclosure. The filter assembly is generally a single-piece unit that can be formed without a rigid frame, thus allowing the filter assembly to be produced at a reduced cost. In one implementation of the invention, the multilayer filter assembly contains at least two particulate removal layers covering, enclosing, and dividing at least two adsorbent regions. One of the adsorbent regions is configured to be placed flush against an interior wall of the electronic enclosure to allow air to flow in and out of the enclosure, while the other adsorbent region is configured to be placed in an upright position in the enclosure with exposed surfaces that allow airflow through this portion of the filter assembly.

Abstract: A dust collecting apparatus for an air conditioner, including an ionizer to electrically charge dust particles in air; and a metal filter having fine metal fibers, disposed at a predetermined distance from a back of the ionizer, the metal filter having a polarity opposite to that of the charged dust particles to electrically collect the dust particles.

Abstract: A filtration system for filtering particulates from air. A plurality of point ionization sources are positioned in the proximity of the periphery of an air flow channel and being oriented to generate ions in the proximity of the air flow channel in a direction generally upstream from each respective one of the plurality of point ionization sources. A particulate collection surface is positioned within the air flow channel in a downstream direction from the plurality of point ionization sources. The particulate collection surface is electrostatically charged in an opposite direction with respect to ground than the electrical charge of the ions. An ion trap is positioned within the air flow channel between the plurality of ionization sources and the particulate collection surface. The ion trap is relatively electrically neutral as compared with the particulate collection surface and the ions.

Abstract: An electric polarizing air filter has a charged screen of high resistivity to suppress avalanche discharge and permit use of a higher polarizing voltage.

Abstract: An air purification assembly (10) that is adapted to be used in combination with a vehicle incorporating a heating, ventilation and air conditioning (HVAC) system (100). The assembly (10) consists of three elements: an electrostatic stabilizing filter (12), a membrane filter (32) and an electronic ionizer (40). The three assemblies (12, 32, 40) when operating in combination with the HVAC system (100) substantially absorb unpleasant odors, smoke, dust, pollen, mold spores, pet dander and particulate matter produced by a vehicle exhaust emissions.

Abstract: A sintered stainless steel filter is used as the grounded electrode of a point-to-plane electrostatic precipitator. Particles flow through, rather than parallel to, the collection plate. Particle collection efficiency is empirically shown to increase as the charged particles are drawn closer to the grounded filter. The utilization of stainless steel fiber filter provides (1) low particle penetration (high particle collection efficiency) of different particle range, (2) applicability to all different particulate components, (3) high loading capacity but low pressure drop (less energy and maintenance needed), (5) low electric voltage for operating the system, and (6) low cost and small dimension.

Abstract: An air filter assembly includes a filter media that is electrostatically charged. The filter media has a first porosity at the inlet side and a second porosity at the outlet side. An electrostatic charge preferably is maintained across the entire filter media to enhance the particle gathering qualities of the media. In one example, multiple layers of filter materials having different porosities are used. In another example, a single filter material having a progressively decreasing porosity is used. One example includes a conductive filter layer that serves as one of the electrodes for the electrostatic field generating portion of the assembly.

Abstract: An electrostaticly charged filtration media is provided comprising a plurality of polymeric structured polymeric film layers having a structured surface defined on at least one face of each structured film layer forming at least in part flow channels, the plurality of structured film layers configured as a stack with the structured surfaces defining a plurality of ordered inlets open through a face of the stack that are in fluid communication with ordered fluid pathways each fluid pathway defined at least in part by at least one discrete flow channel such that fluid can flow substantially unimpeded from one of the inlets to an outlet opening at through another face of the stack wherein layer of fluid pathways is defined by two opposing charged film layers at least one of which is a structured film layer that has flow channels with an average height of from 0.1 mm to 5 mm and an average width of from 0.05 mm to 50 mm and an average aspect ratio of from 0.5 to 10.

Abstract: An electronic air filter assembly includes filter media disposed on opposite sides of an electrified charging screen. The filter media and charging screen are held between outer screens. The outer screens are held together in an assembled condition by pressure-sensitive securements and can be pulled apart to disassemble the filter assembly by applying an outer screen-separating force sufficient to overcome the holding force of the securements.

Abstract: An air filter assembly includes a filter media that is electrostatically charged. The filter media has a first porosity at the inlet side and a second porosity at the outlet side. An electrostatic charge preferably is maintained across the entire filter media to enhance the particle gathering qualities of the media. In one example, multiple layers of filter materials having different porosities are used. In another example, a single filter material having a progressively decreasing porosity is used. One example includes a conductive filter layer that serves as one of the electrodes for the electrostatic field generating portion of the assembly.

Abstract: A multi-stage particulate matter collector of the type used to collect particles from waste industrial gas. The collector can contain multiple narrow and wide zones formed by a plurality of parallel corrugated plates. Contained in the narrow zones are elongated electrodes with sharp leading and/or trailing edges. These electrodes provide a non-uniform electric field near their sharp edges leading to corona discharge. The corona discharge causes particulate matter in the gas flow to become charged. The region in narrow zones away from the sharp edges of the electrodes resembles a parallel plate capacitor with relatively uniform electric field. In this region, particles can be collected on the plates and on the electrode. Wide regions can contain barrier filters (bag filters) with conductive surfaces. The electric field is also relatively uniform in this region causing electrostatic collection on the plates and filter surface.

Abstract: An air purifier, which is mainly comprised of shell body, high-voltage electric sources, ionizing device, at least an electricity-conducting plate, and at least a set of metal filtering net set, wherein, the ionizing device and the metal filtering net set are connected to the high-voltage electric sources of same polarity. And, the electricity-conducting plates are spaced apart by the manner of appropriate distance and are arranged in parallel to the side surface of the metal filtering net set. By arranging the ionizing device at the position of air inlet, the air and micro-dusts sucked into the purifier are charged with charges. And, in the interior, by arranging a metal filtering net set comprised of at least one piece of charged metal filtering net, the charged micro-dusts in the air flowing through the metal filtering net set are expelled by the same polarity charges on the metal filtering net set and pushed toward the electricity-conducting plate located at the position adjacent to the air inlet.

Abstract: Disclosed is a portable air filtration system for removing contaminants from room air. In one embodiment, the air filtration system includes a power supply and an air blower module electrically connected to the power supply. The air filtration system further includes an ionization module engaged with the air blower module and including a first control grid and a high voltage grid electrically connected to the power supply. The air filtration system further includes a filter module removably engaged with the ionization module. The filter module includes a filter and a second control grid. Engagement of the filter module and the ionization module creates an electrical connection between the second control grid and the power supply. Activation of the air filtration system creates a first ionization field between the high voltage grid and the first control grid and a second ionization field between the high voltage grid and the second control grid.

Abstract: A frameless electrostatic air filter used in heating and air conditioning systems includes a plurality of filter media layers and an internal support grill and has no external support grill or frame. The frameless electrostatic air filter has an internal support grill to support the filter media layers and a fabric edging that is secured in place all the way around the edge of the frameless electrostatic air filter. The center of the frameless electrostatic air filter is secured with a plastic rivet. The frameless electrostatic air filter seats and seals tight to the inside lip of filter receptacles.

Abstract: A frameless electrostatic air filter used in heating and air conditioning systems includes a plurality of filter media layers and an internal support grill and has no external support grill or frame. The frameless electrostatic air filter has an internal support grill to support the filter media layers and a fabric edging that is secured in place all the way around the edge of the frameless electrostatic air filter. The center of the frameless electrostatic air filter is secured with a plastic rivet. The frameless electrostatic air filter seats and seals tight to the inside lip of filter receptacles.

Abstract: An air filtration and purification system, particularly adapted for treating contaminated air within a preselected zone of a building interior space, includes a filter and purifier unit comprising first and second stage particle filters, an odor neutralizer comprising an ozone generator, an activated carbon adsorbent media for extracting gaseous compositions exposed to the ozone injected into the airflow stream and an ultrahigh efficiency final stage particle filter. All filter units and the ozone generator are disposed in a cabinet together with one or more air propulsion fans interposed between the second stage particle filter and the adsorbent media. The system is particularly configured for removing air containing tobacco smoke and other contaminants from smoking areas of restaurants and other places of business and may be configured to return purified and odorized air through ceiling ducts to form an air curtain defining the zone.

Abstract: Filter apparatus for trapping particles suspended in gaseous fluid stream generally includes a first and a second electrode with a porous filter therebetween along with electrical contacts for applying a DC voltage across the first and second electrodes. A third electrode is provided and a frame is included for removeably supporting a porous filter, along with the first, second, and third electrodes in order to electrify, by induction, the third electrode with a voltage in the third electrode in order to increase trapping of the particles by the filter apparatus.

Abstract: An air cleaner with separate ozone gas and ionized air outputs, and method of purifying air is provided. The air cleaner includes an exterior housing which houses an ozone generator component and a ionized air generator component. In operation, air is drawn through the air cleaner by means of a blower and is first passed through a multi-layered filter. The air then passes through an ionizer which ionizes the air and induces on it a net negative electric charge. As the ionized air is recirculated back into the device, the negatively charged air is electrostatically precipitated by the filter which maintains a net positive electric charge. The ozone generator component within the housing draws in air via an air pump which produces an output of pressurized air to the ozone generator. Within a mixing chamber of the ozone generator, the pressurized air is mixed with ozone produced therein and is then output through an independent ozone outlet tube.

Abstract: A clog-resistant filter and method for extracting fine particulate contaminants, such as smoke, from a gaseous fluid stream, such as air, uses an induced voltage electrode to efficiently capture the contaminant particles in a filter material whose pores are many times larger than the diameter of the particles to be captured. The filter material is physically so configured to further enhance that interaction and is disposed between at least a pair of electrodes of opposite polarity.

Abstract: A method of charging, coagulating, and filtering out particulates in a fluid. In this method, impurity particulates typified by coloring matter particulates can be efficiently removed without inducing clogging and without the need of maintenance for a long time. Also, a filter element used in this method and a fluid-filtering device are offered. The whole filtering layer of the filter element is made of a conductive layer having numerous voids passing the fluid, or the filter element has plural filtering layers of a conductive material. A filtering layer made of a conductive material is used as an electrically charging electrode.

Abstract: An electrostatic air cleaner is disclosed for use in removing particulate matter from moving streams of air. A high voltage ionizer is used as a corona source to ionize the particulate matter as it approaches the air filter portion of the electrostatic air cleaner. The air filter uses reticulated polyether foam filter media for collecting the particulate matter, and the filter media is non-deliquescent, thus preventing the high-voltage electric field from being dissipated by imbedded water vapor, which is the cause of filter inefficiency in the prior art. In one embodiment, the air filter uses strips of conductive material raised to a very high DC voltage interleaved between strips of conductive material held to ground potential, and these strips are oriented so as to be parallel to the direction of the air flow through the air filter's foam filter media, thereby creating an electric field that is perpendicular to the direction of air flow.

Abstract: The invention relates to apparatus for biological purification and filtration of air. The apparatus includes a coarse filter (1), an ionizer (5), an additional plate (9) and a fine filter (10), which are installed in this order along the path of the gas flow, and a power source (23). The coarse filter (1) is essentially an electrostatic precipitator consisting of three plates (2,3,4) adjacent to each other, the outer-most (2,3) of which are made of a cellular metal and are connected electrically to the opposite-in-sign terminals of the power source (23), whereas the central plate (4) is made of polyurethane foam. The coarse filter (1) abuts closely on the cylindrical nondischarge electrode (6) of the ionizer (5).

Abstract: An air purifier has discharge electrodes which generate a corona emission. These discharge electrodes are disposed within a flow passage provided in the air purifier along with a blower. Also included in the air purifier is a filter which scavenges contaminant particles in the air charged by the discharge electrodes. A control unit detects a discharge current of the discharge electrodes to control a rotational speed of the blower in accordance with the detected emission current.

Abstract: An on board electrostatic filter for a vacuum cleaner is disclosed. The filter includes a pair of conductive filaments insulated from one another and disposed close together in a substantially parallel, side-by-side relationship. Circuitry is provided for applying an electrical potential difference between the two conductors. This dual filament conductor is preferably packed into a relatively small volume in a tortuous configuration, to form a random mesh, or can be oriented in a more regular serpentine configuration. Other embodiments describe the mesh electrostatic filter to purify air in an HVAC system.

Abstract: An electrostatically stimulated air filter and process, contemplates a housing having an fluid intake and a fluid exhaust; a upstream electrode, disposed downstream of the fluid intake, for carrying a ground potential; a filter, disposed downstream of the prefilter, for filtering out contaminants in the fluid; an ionizing electrode, disposed between the filter and the prefilter, for carrying a second potential; and a downstream electrode, disposed downstream of the filter, for carrying a ground potential; and a fan, downstream of the filter, for driving air through the prefilter and the filter. Ionization of incoming fluid occurs as a result of electric fields generated by the downstream electrode, the ionizing electrode, and the upstream electrode. The filter comprises an upstream dielectric layer and a downstream conductive layer, usually fibers coated with activated carbon powder.

Abstract: A vacuum cleaner system includes a vacuum cleaner having a hollow air inlet, an air outlet, a removable dirt bag communicating with the inlet and the outlet, and means for moving initially dirt-laden air from the inlet to the outlet via the bag. The system also includes a charge generator for generating an electrostatic charge of a given polarity on the bag. The system optionally includes a charge generator for generating an electrostatic charge of the given polarity on the initially dirt-laden air.

Abstract: An on board electrostatic filter for a vacuum cleaner is disclosed. The filter includes a pair of conductive filaments insulated from one another and located close together in a substantially parallel, side-by-side relationship. Circuitry is provided for applying an electrical potential difference between the two conductors. This dual filament conductor is preferably packed into a relatively small volume in a tortuous configuration, to form a random mesh, or can be oriented in a more regular serpentine configuration. Other embodiments describe the mesh electrostatic filter to purify air in an HVAC system.

Abstract: An electrostatic air cleaner is disclosed along with a method for removing particulate matter from moving streams of air. A high voltage ionizer is used as a corona source to ionize the particulate matter as it approaches the air filter portion of the electrostatic air cleaner. The air filter uses a pair of reticulated polyether foam filters for collecting the particulate matter. The foam filters are separated by a thin, grid-like layer of semiconductive material (carbon-impregnated polycarbonate) which is raised to a very high DC voltage. The foam filters are also surrounded by thin, grid-like layers of electrically conductive material which are held at ground potential, thus creating a high-voltage electric field through each of the foam filters. The polyether foam filter media is non-deliquescent, thus preventing the high-voltage electric field from being dissipated by such imbedded water vapor, which is the cause of filter inefficiency in the prior art.

Abstract: A reversal color photographic process which comprises subjecting an exposed silver halide color photographic light-sensitive material to a first black-and-white development and then (a) color developing the light-sensitive material with a color developing solution containing a water-soluble stannous salt and a phosphonocarboxylic acid compound or (b) processing the light-sensitive material with a fogging bath containing a water-soluble stannous salt and a phosphonocarboxylic acid compound and then color developing the light-sensitive material, the phosphonocarboxylic acid compound being represented by the general formula (I): ##STR1## wherein R.sub.1 is --COOM' or --PO(OM).sub.2 ;R.sub.2 is a hydrogen atom, an alkyl group containing 1 to 4 carbon atoms, --(CH.sub.2).sub.n COOM' or a phenyl group;R.sub.3 is a hydrogen atom or --COOM';M and M', which may be the same or different, each is a hydrogen atom, an alkali metal atom or an ammonium group;M is 0 or 1; andN is 1 to 4.

Abstract: A high speed color reversal cine film with latent images recorded thereon is so processed as to color-develop the latent images and concurrently reduce the high contrast at the dark end of the tone scale which is inherent in the prior art development of such film. The new method utilizes in the color developer bath increased amounts (in comparison with prior art color developer baths) of a competing coupler such as citrazinic acid and of a silver halide solvent such as ethylene diamine and reduces the amount of a reversal agent such as t-butylamine borane, and also includes a competing non-coupling developer such as 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone, or phenidone, or a derivative thereof.

Abstract: A photographic color developer composition containing a color developer compound and an antioxidant wherein it contains a water-soluble enolizable .alpha.-aminocarbonyl compound as antioxidant is provided. Resistance to atmospheric oxygen of photographic color developer baths is improved.

Abstract: A method is described of making reversal images in Lippmann-emulsions wherein the emulsion is image-wise exposed and subjected to a first stage development so that a negative silver image of the original is formed but some silver halide is left in the exposed areas, and then to a second stage development under fogging conditions to develop said residual silver halide in the exposed areas, whereafter the silver developed in said first and second development stages is bleached and the active silver halide then still remaining in the emulsion is converted to form a positive image.

Abstract: A process is disclosed of forming a reversal dye image. This is accomplished by developing an imagewise exposed photographic element with a black-and-white developer and poisoning the developed silver as a redox amplification catalyst for a peroxide oxidizing agent. The undeveloped silver is then rendered developable to form a silver catalyst image pattern. This latter silver image pattern is then used to catalyze the redox reaction of a peroxide oxidizing agent and a dye-image-generating reducing agent, such as a color-developing agent, or a redox dye-releaser.

Abstract: In a method of processing an image-wise exposed silver halide color photographic material by applying thereto at least a color development processing and a silver removal processing (including performing a bleaching and a fixing separately or simultaneously, (e.g., a blixing)), the improvement which comprises processing, after the color development processing, the silver halide color photographic material with a processing bath containing a compound, as a bleach accelerator, represented by the following general formula (I): ##STR1## wherein R represents an --NR.sup.4 R.sup.5 group, an --O--R.sup.6 group or an --S--R.sup.6 group; R.sup.6 represents an atomic group necessary for forming a ring together with R.sup.1 ; R.sup.1, R.sup.4 and R.sup.5, which may be the same or different, each represents a hydrogen atom or an alkyl group; R.sup.2 and R.sup.

Abstract: A process for producing a printing plate comprising imagewise exposing a light-sensitive material comprising a support with a hydrophilic surface and having thereon an unhardened silver halide emulsion layer, developing the imagewise exposed light-sensitive material with a non-tanning developer, fogging the remaining silver halide, developing the fogged remaining silver halide with a tanning developer to thereby simultaneously harden the emulsion layer at the areas developed, and removing the unhardened emulsion layer, whereby an oleophilic tanning relief image is formed.

Abstract: An exposed light-sensitive silver halide photographic material containing a coupler is processed with a developing bath and thereafter with an amplifying bath containing hydrogen peroxide, said process being characterized in that a compound acting on the silver halide at the unexposed portion of the photographic material is incorporated into the developing bath or into a bath used for a treatment effected after the development and before processing with the amplifying bath.

Abstract: A photographic material is described for making positive images by reversal processing, the material comprising a support and a silver halide Lippmann-emulsion layer the average silver halide grain-size of which is less than 100 nm wherein the grains have been chemically sensitized to fog so that a test portion of the emulsion when coated on a support at a coverage of silver halide corresponding to from about 3 g to about 7 g of silver nitrate per sq.m. gives a density between about 0.20 and about 0.70 upon development without exposure for 6 min at 20.degree. C in a developer of the composition:Hydroquinone: 16.5 gPotassium bromide: 1.7 gSodium salt of EDTA: 1.7 gPotassium metabisulphite: 40 g1-phenyl-5-mercaptotetrazole: 35 gSodium hydroxide and water to make: 1 liter at pH 11.

Abstract: reversal color images are produced in photographic elements which contain a ballasted primary aromatic amine and conventional ballasted color couplers. The photographic element is imagewise-exposed and a negative silver image is formed without forming a dye image. The residual silver halide in the photographic element is then fogged and developed to silver while concurrently forming a color dye image in the nonimagewise-exposed areas of the element. The developed silver is removed without removing the dye image.

Abstract: An adjustable air filter for use in heating, ventilating, cooling, and forced air systems. The air filter includes a media for filtering air and adapted to be cut with scissors, and a frame embracing the peripheral edges of the media. The frame includes a pair of male sections and a pair of female sections respectively telescopingly receiving the male sections. Also, the frame is adapted to be cut with scissors and is preferably formed of polyvinyl chloride. Each of the male sections includes a T-shaped projection and each of the female sections includes a complementary shaped T-shaped slot adapted to telescopingly receive the T-shaped projection for preventing inward separation of the sections from one another. In the preferred form the media is of the electrostatic type and includes at least one layer of polypropylene woven in an egg-crate pattern. Also, the layer preferably includes a pad of washable polyester material.