Abstract: A filter element having a bag of filter medium surrounded by an elastic net hose with a corrugated wall interposed therebetween.

Abstract: An electrostatic filter for separating particles suspended in air has an electrically conducting elongate separation tube and an elongate electrode within the tube connected to a high-voltage direct current source to produce an electric charge current from the electrode to the tube. The tube has air-inlet openings distributed over the surface thereof and is covered with a layer of air-permeable material. The layer of air-permeable material is dimensioned and said air-inlet openings are dimensioned and spaced over the surface of the separation tube to to provide an air resistance such that substantially the same pressure drop of the air passing through the layer and the air-inlet openings to the interior of the separation tube along the whole length of the separation tube covered by the layer is created.

Abstract: An apparatus for electrically separating particles from a gaseous stream in which high-tension means and a plurality of earthed collecting means are positioned in a housing having inlet and outlet means for flow of the gaseous stream therebetween. The high-tension means is connected to a source of high voltage direct current and charges the particles in the gaseous stream. The plurality of earthed collecting elements are disposed in the gaseous stream in the housing to collect charged particles in the gaseous stream. Each collecting element comprises a matrix of alternate flat paper strips and corrugated paper strips glued to each other to form through-flow channels for the gaseous stream. The periphery of the matrix is connected with an electrically conducting, earthed metallic layer to form a block of corrugated paper with edge portions connected to current conducting earthing means.

Abstract: A self contained filter assembly for cleaning air and gas which is light-weight, inexpensive and easily disposable. The filter assembly includes a housing having walls formed of corrugated cardboard. A paper filter element in the form of a paper web is positioned in the housing and is folded in an accordian-like manner to form a plurality of web portions. The web portions form pockets which alternately open in the direction of flow of the air or gas being cleaned. Spacer elements positioned in the web pockets are fastened to the side walls of the housing to reinforce the housing and to counteract outwardly and inwardly lateral forces acting on the housing walls. The spacer elements also are shaped to resist bending along their lengths and to absorb tensile and compression forces occurring in the direction of flow of the air through the housing.