Abstract: A single compact air cleaner unit includes a motor and fan assembly, a mechanical pre-filter, an electrostatic precipitator, a main filter cartridge which is easily removable and which contains both a synthetic mesh media with electrical charges embedded therein and a plastic screen impregnated with activated carbon powder, ionizing needles positioned adjacent a fresh air outlet, an air quality sensing device having an adjustable control for selecting a level of air quality to be achieved, and an automatic control cooperatively associated with the air quality sensing device to keep the unit energized as long as the air being sampled does not meet the selected air quality level.

Abstract: An adjustable frame includes an outer tubular member and an inner cylindrical member disposed in longitudinally adjustable relation, the inner member being of substantially smaller diameter than the interior surface of the outer member so as to provide an annular space between the two members. Inner and outer adapter rings are disposed about the inner cylindrical member within the annular space. The adapter rings have longitudinally tapered mating surfaces for providing a cam action. A sleeve is threadedly supported from the outer tubular member and engages one of the adapter rings for moving it axially relative to the other ring to thereby create a radial expansion force within the annular space, thus locking the inner cylindrical member in a fixed longitudinal position relative to the outer tubular member.