A pneumatic conveyor for powdered to granular bulk material, having adjustable conveyance capacity, is disclosed, the capacity being adjusted by electromagnetic adjustment of a pressure regulator disposed in a conduit used to supply a propellant for drawing the bulk material from a storage container thereof and for conveying it. A supplemental supply of gas, which may be but need not be different from the propellant gas, may be provided to control the flow of propellant gas independently of the first pressure regulator. In this case, the flow of the supplemental gas may itself be controlled by a second pressure regulator. The pressure regulators operate according to the diffuser or Venturi principle. The device may be particularly advantageously applied to the spray-coating of articles with a bulk material.