Model BFC generates no dust during untying, discharging, retying, or collapse and removal operations. Bulk bag discharger has clamp ring above pneumatic telescoping tube, allowing operator to make quick, dusttight connection between bag spout and hopper; as bag empties, it elongates, promoting flow and evacuation. For retying jobs, optional pneumatic flow control valve has SS rods that clinch spout concentrically on horizontal axis for easy tie offs.