Abstract: In a two-stage, electrostatic precipitator for extracting airborne particles, charged plates are electrically connected to each other and physically separated from each other by ferrite spacers so that an impedance of the spacers limits an amount of arc discharge current that will flow when an arc discharge occurs from one of the charged plates. Ferrite spacers can also be provided to electrically connect and physically separate grounded plates in the precipitator. In addition, aluminum spacers can be provided to adjust the impedance of the series of spacers through which an arc discharge current flows, so that the current is a minimum necessary amount for an arc detection circuit to detect.

Abstract: A filter apparatus for filtering chemical gases and odors from a fluid is disclosed. The filter apparatus includes a plurality of filter cartridges which each include a filter material, and a housing which fixes the filter cartridges relative to each other such that the filter cartridges form a W-shape with each filter cartridge forming a leg of the W-shape, to maximize the filtering efficiency of the filter apparatus while minimizing the pressure drop across the filter apparatus. A table top air cleaner is also disclosed,and includes a housing having an inlet opening and an outlet opening, an arrangement for drawing air through the inlet opening and for forcing air out of the outlet opening, and a plurality of filter cartridges which each include a filter material and which are fixed inside the housing relative to each other such that they form a W-shape.