The invention provides methods, systems and apparatus for the metered transport of fine powders into receptacles. The barrel is mounted to a CAF supply conduit and has a cross-sectional area substantially larger than the cross-sectional area of the conduit. The cover has cable openings at the top and bottom that may be shielded by hoods and may also have a latch mechanism to keep the cover in the closed position. In the preferred arrangement, the shaft assembly includes a first component comprising first and second portions, a thin layer of elastomer interposed between the first and second components and a second component which is inserted between the portions to relieve tensile stress in the isolator and, if desired, to impart a compressive stress in the isolator.