Abstract: An improvement in air filtering apparatus of the type having means for providing intermittent reverse flow of air through the filter media of the apparatus to dislodge any accumulations of material from the filter media. Such apparatus is conventionally formed with a collecting air chamber receiving the air to be filtered, which is then fed to a filtered air chamber separated from the collecting chamber by a grid plate with air passages therethrough. Filter media such as filter bags or the like are arranged in the grid plate air passages to filter the air passing through to the filtered air chamber. The invention provides an improved air plenum blower fan arrangement providing a relatively straight reverse air flow path from the fan discharge to improve the efficiency of air transfer between the fan and the filter media to effect desired cleaning of the filter media.