Rotary feeder
Rotary feeders, also called rotary airlocks or rotary valves, are devices that move bulk solids from storage hoppers into a pneumatic conveying system while keeping different air pressures separated. They are common in industrial and agricultural plants for handling powders, granules, crystals, and pellets.
How they work: A rotor with multiple vanes spins inside a housing. As it turns, material is drawn into the rotor pockets and discharged into the downstream line at a controlled rate. They are driven by electric motors or small engines and can connect to either pressure or vacuum conveying systems.
Key parts and options: The main components are the rotor, housing, head plates, seals, and bearings. Vanes are cast or welded to the rotor. Housings can be cast or sheet metal, and are made from cast iron, carbon steel, or stainless steels (304/316), with other materials available. Wear protection such as hard chrome or ceramic lining can be added, and grease or air purge fittings help protect seals from contaminants. Inlet and outlet can be drop-through or side-entry configurations. Some designs use outboard bearings for rugged, high-wear or high-temperature service.
Applications and industries: Rotary airlocks are suited for dry powders, granules, crystals, and pellets used in cement, ore, sugar, minerals, grains, plastics, dust, flour, gypsum, lime, coffee, cereals, pharmaceuticals, and many other materials. They are used in cement plants, mining, chemicals, plastics, food processing, wood and grain operations, and more. They also serve in dust control devices and as isolation points in air or gas flows.
Airlock as an isolation device: In the event of a fire or deflagration, rotary airlocks can help slow flame spread by sealing off air and material flow. For this purpose, NFPA standards specify features like a precise rotor-to-housing clearance, suitable materials, and a minimum number of rotor vanes.
Special designs and features: Some feeders are designed to dose material into a conveying line for accurate feeds. There are standard and heavy-duty models (the latter use outboard bearings for durability). Drop-through units are common in rugged, high-pressure systems, while blow-through or low-profile designs offer high capacity in tight spaces. Quick-clean versions exist so units can be disassembled and cleaned without tools, reducing downtime. Clean-in-Place (CIP) versions are used in dairy, pharmaceutical, food, baking, chemical, plastics, paint, and powder-coating applications to prevent cross-contamination.
Other variants: Some models include a knife to cut oversized material and prevent rotor blockage. There are also lighter-duty filter-type feeders for dust collectors and secondary-fuel discharge applications in plastics or wood processing.
In short, rotary feeders control the flow of bulk materials into pneumatic systems while maintaining air isolation, and they come in many configurations and materials to fit a wide range of industries and processes.
This page was last edited on 2 February 2026, at 19:09 (CET).