Dust filter socks, for easy installation in filter housing of dust extraction system, are formed with compact, ultra-sound welded, deformation-fold end-closure which does not exceed sock width

摘要

A filter sock of elongated tubular pattern, is made from gas permeable material, closed at one end by flattening the originally circular section end in order to bring two internal surface sectors (7, 8) in contact, then permanently fusing them to provide a gap-free closure (10). Alternatively a 120[deg] tri-lobal closure may be achieved by making three successive , half sector, flattened seals. The sealing is by ultrasonic induced thermoplastic welding, facilitated by use of a micro-porous PTFE foil laminate filtration fabric.