Abstract: In pneumatic low pressure dust extraction apparatus, filter bags are cleaned by reverse flow of air. Each cleaning operation includes a first shock phase of short duration (not longer than 0.05 sec) but at high flow intensity by which accumulated layers of dust are thrown off the outside of the bag, followed by a rinsing phase of greater duration (not longer than 1 sec e.g. 0.20-0.30 sec) but at lower flow intensity during which remaining dust is blown out of the filter cloth and the cloth is allowed to lie back gradually on its support. The apparatus includes a cleaning-air tank incorporated in the filter housing for storage of compressed air in the close vicinity of apertures of the filter bags. The height of the tank exceeds its distance from the bag apertures. There is a valve for each filter bag and it has delivery means extending into the region of the bag aperture. The duration of the reverse flow for cleaning is adjustable for obtaining optimum results suited to the operating conditions.

Abstract: In pneumatic low pressure dust extraction apparatus, filter bags are cleaned by reverse flow of air. Each cleaning operation includes a first shock phase of short duration (not longer than 0.05 sec) but at high flow intensity by which accumulated layers of dust are thrown off the outside of the bag, followed by a rinsing phase of greater duration (not longer than 1 sec e.g. 0.20-0.30 sec) but at lower flow intensity during which remaining dust is blown out of the filter cloth and the cloth is allowed to lie back gradually on its support. The apparatus includes a cleaning-air tank incorporated in the filter housing for storage of compressed air in the close vicinity of apertures of the filter bags. The height of the tank exceeds its distance from the bag apertures. There is a valve for each filter bag and it has delivery means extending into the region of the bag aperture. The duration of the reverse flow for cleaning is adjustable for obtaining optimum results suited to the operating conditions.