Abstract: A dust suppressor for reducing or substantially eliminating dust in the loading of a particulate commodity, operating on a "dead box" principle but without the use of power operated valves. The dust suppressor normally operates on a three-stage principle, the first stage utilizing an adjustable damper valve which slows the velocity of flow, the second stage comprising a fixed deflector which directs and initially smooths the flow, and the third stage comprising a counterweighted, automatically operating butterfly valve which finally shapes and smooths the flow. Maximum dust suppression is obtained because dust cannot escape the dust suppressor without being forced back into the grain flow, because the velocity of the grain flow is reduced and because the grain flow discharged from the dust suppressor is smooth, non-turbulent and shaped.