Noise attenuator for duct type mining ventilation - has perforated noise attenuating blocks between inner and outer casing

摘要

The ventilator casing has a cylindrical cavity between outer casing and inner casings which are supported by distance pieces, e.g. profiled rods or tubes. Noise attenuating perforated plastics blocks are equidistant spaced along the outer periphery of the inner casing. A shouldered flange unit reinforces the outer casing. Space between the perforated blocks may be filled with polyurethane foam. The shouldered flange units may be screwed or bolted to the casing.