ENGINEERED FOR THE PROCESS
Rotary Valve Capacity Calculator and Formula
Estimate rotary feeder capacity in kg/h and t/h, then review the operating factors that change real output.
What this calculation can—and cannot—tell you
The formula converts usable rotor displacement into a theoretical mass flow. It is useful for comparing an initial valve size and speed against a required throughput, provided the loose bulk density and expected pocket filling are realistic.
Four inputs used by the calculator
- Usable rotor displacement per revolution—not only the nominal inlet size.
- Rotor speed under the intended operating duty.
- Estimated pocket filling for the actual material behavior.
- Representative loose bulk density at the valve inlet.
Engineering checks still required
- Pressure differential, air leakage and product fallback.
- Starting torque, drive margin and continuous-duty requirements.
- Particle damage, abrasion, buildup and rotor-clearance risks.
- Flange dimensions, available height and maintenance access.
Use the estimate below as a starting point, then confirm the proposed configuration against process data and an approved project drawing.
CAPACITY ESTIMATE
Rotary valve capacity calculator
Enter the usable displacement per revolution, rotor speed, estimated pocket filling and loose bulk density. The result is a theoretical mass flow and should be confirmed with representative material data.
Worked example
For 2.5 L/rev at 20 rpm, 75% filling efficiency and 650 kg/m³ bulk density, the estimate is 1,462.5 kg/h, or about 1.46 t/h.
Why actual capacity changes
- Cohesive, aerated or poorly flowing powders may not fill each rotor pocket completely.
- Pressure differential, air leakage and product fallback can reduce effective throughput.
- Large particles and fragile products may require a lower speed or a different pocket design.
- Drive sizing must consider torque and starting load, not capacity alone.
APPLICATION NOTES
Engineering considerations for Rotary Valve Capacity Calculation
The main design objective is estimating realistic throughput instead of relying on nominal rotor volume. Confirm rotor displacement, speed, filling efficiency and bulk density before fixing the valve size, rotor and drive arrangement.
Use conservative filling efficiency for cohesive or poorly aerated powders and verify the result against the process target. Sercan reviews these details against capacity, installation interface and maintenance access before issuing a project drawing.
Recommended project checks
- Provide representative material and bulk density data.
- State normal and maximum temperature and pressure conditions.
- Confirm flange dimensions, available height and drive orientation.
- Define the expected duty cycle and maintenance target.
TECHNICAL FAQ
Questions before selection
How is rotary valve capacity calculated?
Multiply usable rotor displacement by revolutions per minute, 60 minutes per hour, filling efficiency and bulk density. Convert litres to cubic metres by dividing by 1000.
Is the calculator result the guaranteed output?
No. It is a theoretical estimate. Material flowability, pressure differential, air leakage, rotor geometry and operating conditions can change actual throughput.
Which bulk density should be used?
Use representative loose bulk density at the valve inlet. Do not substitute particle density, because it can substantially overstate capacity.