An air filter medium includes a first porous PTFE membrane and a second porous PTFE membrane. The air filter medium has a first main surface and a second main surface, and the first porous PTFE membrane and the second porous PTFE membrane are arranged so that an air flow moving from the first main surface to the second main surface passes through the first porous PTFE membrane and subsequently through the second porous PTFE membrane. A proportion of areas occupied by the plurality of nodes on a surface of the first porous PTFE membrane is in the range of 1.5 to 3.0% and an average of the areas of the plurality of nodes is 200 μm2 or more.

Water impermeable, air permeable membrane assemblies are described herein. In some embodiments, the assemblies include a polymer membrane and at least one support structure. Certain assemblies are configured to provide an acoustic impedance having phase angle of +45 degrees to −45 over a frequency range of 50 to 20,000 Hz.

A multilayer composite materials nano-scale filter apparatus includes a vessel including an inlet and an outlet; a main line for flowing contaminants to the vessel through the inlet; a filtration assembly disposed in the vessel for separating particulates from the contaminants to obtain filtered liquids, the filtration assembly including a first magnetic layer, a second magnetic layer, an intermediate filtration layer disposed between the first magnetic layer and the second magnetic layer; and an outlet line for flowing the filtered liquids out of the vessel through the outlet. The intermediate filtration layer is a steel layer or a resin layer.

To provide an injection mold capable of filling a necessary resin material for obtaining a desired molded article in a cavity space of a fine mesh structure, there is provided an injection mold according to an embodiment of the present invention composed of a core mold and a cavity mold, in which a cavity space is formed when the core and cavity molds are in a contact with each other, the cavity space surrounding a plurality of contact areas between the core and cavity molds. In the injection mold according to an embodiment of the present invention, at least one of the core and cavity molds has a through-hole which has an opening in a parting plane of the core and cavity molds and extends from the opening to an outside of the injection mold, the parting plane corresponding to the contact areas between the core and cavity molds.

Methods and apparatuses for screening are provided. Embodiments include a screen basket apparatus for screening material, comprising a grid frame having a plurality of openings arranged in a lattice and a plurality of screening cartridge assemblies affixed to the grid frame to cover the respective openings of the grid frame. The screening cartridge assembly includes a case and a screen assembly fitted into the case, and may be affixed to a set of transversal member of the grid frame. The case may be formed of a single injection molded piece integrally formed by injection molding one of a polyurethane or a thermoset polymer. The screening elements together form a generally continuous screening surface across the exterior of the grid frame, which reduces blinding and is resistant to wear and tear.

An air filter medium having a large thickness and a low filling factor, a filter pack, an air filter unit, and methods for producing the air filter medium, the filter pack, and the air filter unit are provided. The air filter medium includes a fluororesin porous film having a portion with a filling factor of 3.5% or less, and the portion with a filling factor of 3.5% or less has a thickness of 45 μm or more.

A high-efficient particulate air filter assembly including a high efficient particulate air filter for filtering the intake air as it enters an air purifying system is provided. The air filter assembly can further include a housing configured for use in an air purification system; a first prefilter positioned in the housing upstream from the particulate air filter; and an electrostatically charged substrate positioned in the housing downstream from the particulate air filter. The air filter assembly can further include a second prefilter having a paper layer; a carbon layer; a zeolite layer; a mesh layer; and a foam layer.

Method for preparing a membrane from fibril cellulose includes supplying fibril cellulose dispersion on a filter layer, draining liquid from a fibril cellulose dispersion by the effect of reduced pressure through the filter layer that is impermeable to fibrils of the fibril cellulose but permeable to the liquid to form a membrane sheet on the filter fabric, applying heat on the opposite side of the membrane sheet to the membrane sheet while continuing draining of the liquid through the filter layer by pressure difference over the filter layer, and removing the membrane sheet from the filter layer as a freestanding membrane.

A flow guide mesh has a water inlet side and a water outlet side opposite to each other, wherein a first water isolating material is provided on the water inlet side of the flow guide mesh to seal a part of the water inlet side, and an effective water inlet width is defined on the water inlet side, a second water isolating material is provided on the water outlet side of the flow guide mesh to seal a part of the water outlet side, and an effective water outlet width is defined on the water outlet side. In addition, the flow guide mesh has a comb-like structure comprising at least one comb tooth within the effective water outlet width of the water outlet side. Also disclosed are a membrane element and a filter assembly.

Described are ion-exchange membranes that include a porous polymeric membrane and imidazole ion-exchange groups at surfaces of the membrane; ion-exchange membranes and filters that contain the ion-exchange membranes; and methods of using the ion-exchange membranes and filters for separating charged biological molecule from a liquid.