A metering device for metering granular product into a pressurized conduit of a pneumatic conveyor has a tubular housing oriented vertically. Intake and discharge openings are defined in opposite housing walls with blank walls between the openings. Upper and lower hubs are rotatably mounted and sealed in ends of the housing above and below the intake and discharge openings. An upper surface of the lower hub slopes downward toward an outer edge thereof. The upper and lower hubs are fastened to a drive shaft extending along the housing axis and a meter drive rotates the drive shaft at a selected rotational speed. Each of a plurality of flexible blades extends between the upper and lower hubs and has an outer edge wiping the inner wall surface of the housing such that a sealed blade chamber is formed between adjacent blades and one of the blank walls as the hubs rotate.
