Abstract: Air cleaning device has a particle charging zone comprising a conducting sheet having a plurality of apertures, through which air can be passed, and a plurality of corona emitters each associated with an aperture, and a filter.

Abstract: A particle precipitation device for removing particles entrained in a gas stream includes an array of passages through which a gas stream can be directed relatively freely. The passages are provided between plastics walls adapted to create an electrical field within the array. The plastics walls may have areas of conductive material in contact therewith. High and low electrical potentials alternately applied to isolated areas of the conductive material provide charged sites in the array for collecting particles from the gas stream. Alternatively, the plastics walls may have electret properties.

Abstract: A particle precipitation device for removing particles entrained in a gas stream includes an array of passages through which a gas stream can be directed relatively freely. The passages are provided between plastics walls adapted to create an electrical field within the array. The plastics walls may have areas of conductive material in contact therewith. High and low electrical potentials alternately applied to isolated areas of the conductive material provide charged sites in the array for collecting particles from the gas stream. Alternatively, the plastics walls may have electret properties.

Abstract: A particle precipitation device for removing particles entrained in a gas stream includes an array of passages (10) through which a gas stream can be directed relatively freely. The passages are provided between plastics walls adapted to create an electrical field within the array. The plastics walls may have areas of conductive material (1, 2) in contact therewith. High and low electrical potentials alternately applied to isolated areas of the conductive material provide charged sites in the array for collecting particles from the gas stream. Alternatively, the plastics walls may have electret properties.