Rotary valve capacity calculation is used to estimate whether a rotary airlock valve or rotary feeder can deliver the required amount of powder or granular material. The result depends on rotor volume, speed, filling efficiency, material bulk density and the operating condition around the valve.  Basic capacity calculation logic  A practical capacity estimate starts with the volume moved by each rotor revolution. The usable capacity is then adjusted by speed and by filling efficiency. For weight-based capacity, the result must also consider bulk density.  A common selection logic is: capacity is affected by rotor volume per revolution, rotor speed, filling efficiency and material bulk density. Actual capacity should be checked against the application, pressure condition and material flowability.  Data needed before sizing   Material name and whether it is powder, granule, pellet or mixed material.  Bulk density, particle size, moisture and flowability.  Required throughput per hour.  Pressure condition above and below the valve.  Temperature and whether the material is sticky, abrasive or fragile.  Inlet and outlet flange size, installation direction and available height.   Why filling efficiency matters  The rotor pocket is not always completely filled. Material bridging, poor flowability, pressure difference, rotor speed and inlet design can reduce the effective filling rate. This is why the same valve size may perform differently in two applications.  Capacity calculation and pneumatic conveying  For pneumatic conveying, capacity cannot be checked by valve volume alone. Air leakage, pressure difference, seal condition and conveying line stability also affect performance. If the valve is used as an airlock feeder, selection should consider both feeding capacity and air leakage control.  Related FUWEI guides  For dimensional checks, see  Rotary Valve Sizing Calculator, Dimensions & Capacity . For leakage, jamming or capacity loss, see  Rotary Airlock Valve Repair & Troubleshooting Guide . For replacement decisions, see  Rotary Airlock Valve Repair & Rebuild Support .  Selection note  Send FUWEI your material name, bulk density, capacity requirement, pressure condition and flange size. The selection should be confirmed from real process data rather than from a single theoretical formula.