Abstract: A non-woven, relatively thin filter media is formed of fine denier fibers wherein the media exhibits the characteristics of developing an electrostatic charge in the presence of a substantially dry air stream moving at a speed of at least 200 feet per minute. The fibers are selected from the group containing polyester, nylon, and polypropylene. A length of filter material so formed is moved or passed through an air stream or path containing weld smoke. The moving air causes the unique filter media to become electrostatically charged so that the fine particulate matter from the gaseous stream are removed more effectively than before.

Abstract: Air contaminated with combustible dust particles is removed and subjected to a high density air scrubber which safely removes the fine combustible dust particles from the contaminated air. The resulting water saturated, cleansed air is mixed with a continuously regulated amount of drier outside air until a desired absolute humidity is achieved, the regulation being responsive to the relative humidity changes within a work area in which the humidity is to be controlled. The air mixture is then conveyed into the work area which imparts a known temperature rise thereto. The temperature rise lowers the relative humidity of the air mixture to the desired level.

Abstract: A dust contaminated air stream enters a cyclone-type dust separator having a curved outer wall and follows a path that spirals downwardly and inwardly. The primary air stream, which occurs during the first revolution, is separated from the subsequently occurring secondary air stream by an inner wall or baffle in the form of a curved member extending inwardly into the separator approximately one-half revolution along a path generally paralleling said air stream and defined by a continuously decreasing radius. The inner wall terminates at the dust separation point, which is also the turning point of the air stream. The inner wall and corresponding portion of the outer wall converge slightly to cause an acceleration of the primary air stream. A discharge cylinder extends downwardly through the top of the separator into the interior thereof and has a lower edge or inlet at a point in substantially the same horizontal plane as the above-mentioned turning point of the air stream.