Abstract: Composite filtering structures comprising nanofibers spatially distributed between microfibers, wherein on the nanofibers and on the microfibers a palisade of protrusions of nanometric sizes in the form of nano-protrusions is produced, which palisade comprises nano-protrusions oriented with respect to the fiber surface at an angle ranging from about 70° to about 120°. A method of obtaining such composite filtering structures by a method that includes feeding a thermoplastic material from an extruder to at least one fiber formation die, stretching formed fibers coming out from the die, which fibers being still in a molten phase, to smaller sizes by a stream of hot air flowing tangentially to the fibers, collecting the fibers after their solidification and thus forming a mat of packed fibers providing a filtering structure, and subjecting the filtering structure to chemical etching.

Abstract: Composite filtering structures comprising nanofibres spatially distributed between microfibers, wherein on the nanofibers and on the microfibers a palisade of protrusions of nanometric sizes in the form of nano-protrusions is produced, which palisade comprises nano-protrusions oriented with respect to the fibre surface at an angle ranging from about 70° to about 120°. A method of obtaining such composite filtering structures by a method that includes feeding a thermoplastic material from an extruder to at least one fibre formation die, stretching formed fibres coming out from the die, which fibres being still in a molten phase, to smaller sizes by a stream of hot air flowing tangentially to the fibres, collecting the fibres after their solidification and thus forming a mat of packed fibres providing a filtering structure , and subjecting the filtering structure to chemical etching.

Abstract: The present invention relates to a method for manufacturing a pleated filter (1) obtained by pleating a filtering material and folding the pleated filtering material to form a cylindrical configuration, which method further comprises applying at least one layer of fibrous covering on the outer surface of ridges of the pleats, which fibrous covering comprising melt-blown fibres (3) of thermoplastic polymer, wherein the pleated filter (1) is arranged in parallel to the blowing head which blows the molten polymer forming fibres, whereas at the same time the filter (1) performs rotational movements and/or reciprocating motions, while the distance of the blowing head from the said outer surface of the filter (1) is selected so that the fibres blown from the head from the said outer surface of the filter (1) is selected so that the fibres blown from the blowing head at the time of contacting the pleat ridges are still in a plastic state.

Abstract: Method and apparatus are provided for making a filter element by spinning fibers from one or more dies onto a collector, including designated combinations providing designated filter characteristics.

Abstract: A coalescer has variable characteristics including variable diameter of individual fibers along their length such that an individual fiber has differing diameters at different points along its length, and including variable porosity.