Abstract: The invention concerns a gas filter unit or cartridge type, including a filter material put together to form one or several filter bags, and a support frame of essentially U-shaped cross-sectional configuration, including a web portion and two lateral leg members in adjoining relationship, the filter material closest to the mouths of the filter bags being clamped in position between said lateral leg members. In accordance with the invention, the frame includes profile sections of a flexible material, preferably a plastics material, at least one of said lateral leg members being hingedly interconnected with the web portion, in addition to which locking means are provided to retain the corresponding lateral leg member in its clamping position in which it is pivoted into engagement with the other lateral leg member.

Abstract: An electrostatic filter of a combination of a layer of filter material having electrostatic properties and a layer of filter medium without electrostatic properties. The medium is a lofted material arranged to retain particles in the sub-micron and lower micron ranges, and in use, is located upstream of the material. The invention also includes a method of filtering dust from the atmosphere utilizing the electrostatic filter.