Summary
A
powder rotary valve datasheet contains critical engineering data required for proper system integration. Misinterpreting terms like fill factor, torque rating, or differential pressure can lead to undersized equipment and premature failure. This guide explains how to read a rotary airlock feeder datasheet line by line, ensuring you select the right valve for your bulk solids application.
General Information Section
This section identifies the basic model and configuration.
Model Number: Indicates size (DN200), rotor type (Drop Through), drive type (Direct Drive), and material code (SS316L).
Rotor Speed (RPM): Specifies the operating speed range. Higher RPM increases capacity but also increases wear and heat generation.
Weight: Important for structural support calculations, especially for rooftop dust collector installations.
Performance and Capacity Data
This is the most critical section for process engineers.
Capacity Calculation
Manufacturers list theoretical capacity based on:
Capacity = Pocket Volume × RPM × Bulk Density × Fill Factor
Fill Factor (FF): This is the percentage of the rotor pocket actually filled with material.
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Free flowing powders (plastic pellets): FF = 0.80 - 0.95
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Average powders (sugar, flour): FF = 0.60 - 0.75
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Cohesive powders (milk powder): FF = 0.40 - 0.60
Always use the recommended fill factor from the datasheet rather than assuming 100% fill.
Torque Requirement
The datasheet lists Starting Torque and Running Torque (Nm or lb-in).
Starting Torque is typically 2 to 3 times the running torque. Ensure your gearmotor has sufficient starting torque to overcome static friction and initial material load.
If the calculated torque exceeds the valve's limit, you must reduce RPM or select a larger valve.
Mechanical and Pressure Ratings
These parameters define the valve's physical limits.
Differential Pressure (dP): The maximum pressure difference the valve can seal.
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Standard: 0.35 to 0.5 bar
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Heavy Duty: Up to 1.5 bar
Exceeding this rating causes excessive air leakage and potential rotor blowout.
Rotor Tip Clearance: The gap between the rotor tip and housing bore.
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Standard: 0.15 - 0.25 mm
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Abrasive Service: 0.25 - 0.40 mm (initial, adjustable)
Tighter clearances provide better airlock but are less tolerant of thermal expansion or minor misalignment.
Temperature Rating: Maximum continuous operating temperature for the valve body and seals. High temperature applications require graphite packing instead of rubber seals.
Material and Construction Details
Verify compliance with your industry standards.
Housing Material: GG25 (Cast Iron), SS304, or SS316L.
Rotor Type: Closed End (best for pressure sealing) or Open End (for granules).
Shaft Seal Type: PTFE (chemical), NBR (standard), Silicone (food/pharma), or Graphite (high temp).
Surface Finish: For stainless steel, Ra ≤ 0.8 µm indicates a sanitary polish.
Motor and Drive Specifications
Ensure compatibility with your electrical supply.
Power (kW/HP): Must meet or exceed the calculated torque requirement at the desired RPM.
Voltage/Frequency: Verify 230V/50Hz, 400V/50Hz, or 460V/60Hz.
Ingress Protection (IP Rating): IP55 (standard industrial) or IP65/IP69K (washdown).
Efficiency Class: IE2 or IE3 for energy savings.
How to Cross-Check the Datasheet with Your Process
Follow these steps to validate the quotation:
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Calculate Required Capacity: Determine your required m³/hr.
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Consult the Curve: Find the RPM needed to achieve this capacity at your material's bulk density and fill factor.
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Check Torque: Ensure the motor torque at that RPM is higher than the valve's running torque.
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Verify Pressure: Confirm the valve's dP rating exceeds your system's max differential pressure.
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Review Temperature: Ensure the seal material suits your product temperature.
If your calculated requirement is at the extreme limit of the datasheet curve, always upsize to the next valve diameter.
FAQ
What happens if I ignore the fill factor?
You will likely undersize the valve. Assuming 100% fill when the material only achieves 60% fill means your valve will only deliver 60% of the required capacity.
Is higher RPM always better for capacity?
No. High RPM increases wear, heat, and can cause product degradation. It also increases the chance of centrifugal ejection of material from the pockets.
Why does the datasheet list both kW and RPM?
Because torque is the real measure of work. A motor with high kW at very low RPM might not generate enough torque for a rotary valve. Always look at the torque curve provided by the motor manufacturer.
Does Doebritz provide detailed datasheets with torque curves?
Yes. Doebritz supplies comprehensive datasheets including capacity tables, torque requirements, and pressure drop curves for all powder rotary valves and rotary airlock feeders.
Conclusion
Reading a
powder rotary valve datasheet is a skill that prevents costly mistakes. By understanding fill factors, torque requirements, and pressure ratings, you can confidently select a rotary airlock feeder that performs reliably for years. Never rely solely on "inch size" or "price"—rely on the data.
Contact Doebritz Shanghai Co., Ltd. to request a detailed technical datasheet for our rotary valves or to have our engineers verify your calculations.
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