Intra-nasal filter devices and methods for their manufacture and use are disclosed. An intra-nasal filter device includes: a first stage filter proximate the septum; and a second stage filter comprising a flexible material extending upwardly from the first filter stage filter; wherein the flexible material comprises: an impedance in the range of 0.02 to 0.2 cmH.sub.2O; an effective cross-sectional area in the range of 0.2 to 2 square inches; and a plurality of radially extending geometric structures disposed along an axial length of the second stage.

An air filter including a filter support that supports polymeric sorbent particles. The polymeric sorbent particles are the reaction product of a hydrolyzed divinylbenzene/maleic anhydride precursor polymeric material with a nitrogen-containing compound, with the nitrogen-containing compound being ionically attached to the hydrolyzed divinylbenzene/maleic anhydride.

A cassette filter for cleaning a fluid includes: a frame; and a plurality of filter elements having a filter medium provided with a folding. The plurality of filter elements are accommodated in a frame such that at least two adjoining filter elements of the plurality of filter elements are arranged at an acute angle to one another and form a V-shaped arrangement. Each of the plurality of filter elements has folded edges which are formed by fold peaks and fold valleys and extend perpendicularly to legs of the acute angle. Each filter element of the plurality of filter elements is provided with foldings such that a height of the respective filter element is smaller at all edge regions than a height in a central region of the respective filter element, and smaller folding surfaces than the central region result at the edge regions.

A filter arrangement for threadably securing to a filter head includes a housing having a surrounding wall defining an interior volume, an open mouth providing access to the interior volume and an end opposite of the open mouth. The surrounding wall has an exterior and an interior. A filter media construction is operably held within the interior volume. A sleeve, distinct from the housing, is secured to the exterior of the surrounding wall adjacent to the housing mouth and extending partially along the surrounding wall. The sleeve has an exterior and an interior. The exterior of the sleeve defines mounting threads constructed and arranged to removably mount with the filter head, when the filter arrangement is secured to the filter head. The interior of the sleeve is against the exterior of the surrounding wall. A first seal member is oriented against the sleeve to create a seal with a filter head, when the filter arrangement is secured to the filter head. A filter assembly includes a filter arrangement and a filter head. The filter arrangement is removably secured to the filter head by a threaded connection between the sleeve and the filter head. A system includes an engine utilizing a liquid and a filter assembly in fluid communication with the engine to filter the liquid. Methods of making filter arrangements include utilizing structures characterized above.

Filter media packs that utilizes a zig-zag folding pattern on deeply corrugated filter media are described. The filter media is scored, folded, and secured into position to form the filter media pack. The filter media pack may be secured using a self-supporting structure (e.g., via tacking adhesive used to secure adjacent folds). The filter media pack contains unique features to optimize filtration performance, such as maximized inlet and outlet face flow areas. In some arrangements, the filter media pack exhibits improved flow characteristics and dust-holding capacity via upstream and downstream channels that have different cross-section al shapes and/or sizes. The upstream and downstream channels may comprise, for example, circular, diamond shaped, or fish-scale shaped openings.

A filter apparatus includes a filter, such as a cartridge, positioned within a housing. The filter apparatus has multiple ports and valves, so as to allow a user to easily switch between a filtration mode of filtering fluids and a maintenance mode of cleaning the filter. The filter can have a filter substrate in a housing and after filtrate builds up on the substrate, the substrate can be cleaned by directing a spray of fluid, such as from a ring of nozzles at the top of the housing, onto the substrate. A maintenance port can be provided to drain the debris washed from the substrate. The filter can switch between a backwash mode and a filtration mode.

A variable efficiency filter media. The variable efficiency filter media is a composite media formed of at least two different types of filter media, such as standard efficiency media and high efficiency media. The variable efficiency filter media has at least two different efficiency levels. The different efficiency levels can be spread across different zones. The filter media types for both the standard and high efficiency media can be spun media, melt blown media, nanofiber media, micro-glass media, cellulose media, carded staple fiber media, and the like. The variable efficiency filter media may be produced by any of an air laid or wet laid process.

Filter media packs that utilizes a zig-zag folding pattern on deeply corrugated filter media are described. The filter media is scored, folded, and secured into position to form the filter media pack. The filter media pack may be secured using a self-supporting structure (e.g., via tacking adhesive used to secure adjacent folds). The filter media pack contains unique features to optimize filtration performance, such as maximized inlet and outlet face flow areas. In some arrangements, the filter media pack exhibits improved flow characteristics and dust-holding capacity via upstream and downstream channels that have different cross-sectional shapes and/or sizes. The upstream and downstream channels may comprise, for example, circular, diamond shaped, or fish-scale shaped openings.

A high pressure filter assembly with minimal pressure drop includes a filter assembly with a cylindrical filter element housing having a central inlet at one end and an angled peripheral outlet on an opposite end, and an inside-out flow filter element coupled to the inlet having a lower endcap and an upper endcap assembly and filter media extending between the upper endcap assembly and the lower endcap, and wherein the upper endcap assembly includes an upper end cap and a diverter plate coupled to and spaced from an upper endcap of the upper end cap assembly with at least one vertical strut, wherein the diverter plate is angled in the direction of the angled peripheral outlet in a centerline plane of the peripheral outlet.

A porous filter element comprises hollow cylindrical porous metal medium having a first end and a second end, the hollow cylindrical porous metal medium comprising a plurality of pleats longitudinally arranged along an axis from the first end to the second end, each pleat comprising a plurality of portions each having a height to width aspect ratio of about 1:≥1 is disclosed, along with a method of filtration using the filter element.