How To Select The Proper Rotary Airlock Valve
What this video shows
Prater’s selection video frames rotary-airlock choice around the actual duty: material behaviour, required solids rate, pressure differential, temperature and whether the valve must meter, discharge or feed a conveying line.
What the footage shows
The video presents rotary-airlock selection as an application problem rather than a catalogue-size decision.
It connects valve type and capacity to the handled material, process pressure, temperature, required displacement and the equipment interface above and below the valve.
Process challenge
A valve selected only from nominal opening size or theoretical pocket volume can miss the real solids rate, leak excessive air, damage particles or become difficult to clean.
The useful capacity changes with pocket filling, rotor speed, pressure differential and material flowability.
Demonstrated solution
Prater recommends defining the process duty first, selecting the appropriate airlock family and then matching volumetric displacement to the mass-flow requirement.
The supporting sizing method relates required mass rate, bulk density, expected fill efficiency and rotor speed instead of treating gross pocket volume as delivered capacity.
Technical overview
Key features
- •Selection by material, process duty and pressure differential
- •Capacity check using mass rate, bulk density, fill efficiency and rotor speed
- •Review of temperature, particle size, duty cycle and upstream head load
- •Distinction between metering, gravity discharge and pneumatic-conveying service
Benefits
- •Turns valve selection into a documented process-duty review
- •Exposes fill-factor and leakage assumptions before purchase
- •Creates measurable inputs for vendor sizing and acceptance checks
Typical applications
- •Gravity discharge below bins, filters, cyclones and dust collectors
- •Metered feeding of powders, granules, crystals and pellets
- •Pressure or vacuum pneumatic-conveying interfaces
Partner with powderbulkvideos.com
Give your technical videos a connected industry presence.
Build a connected company, video and technology presence with clearly labelled partner visibility and measurable placement performance.
About this video
Start with the duty, not the flange size
First question: Decide what the valve must do in the process.
A gravity discharge below a dust collector, a volumetric feeder under a hopper and an airlock feeding a positive-pressure conveying line place different demands on the same basic rotor-and-housing architecture.
The inlet size still matters, especially for cohesive material, but it is only one part of the selection.
Convert mass flow into realistic pocket displacement
Capacity basis: Rotary-valve capacity is volumetric, while most plant requirements are specified as mass per hour.
Convert the required mass rate using the representative bulk density, then divide by rotor speed and the expected pocket fill efficiency.
Prater’s published sizing relationship expresses the required displacement as mass rate divided by bulk density, fill efficiency and rotor speed.
Use consistent units and document whether density is loose, settled or aerated.
Fill efficiency: Pockets rarely fill to their geometric volume under operating conditions.
Cohesive powder, counter-flowing leakage air, a restricted inlet or high speed can all reduce filling, while a free-flowing granular product under adequate head may fill more consistently.
A capacity sheet without its fill-factor assumption looks precise but tells the next engineer very little.
Material behaviour changes the valve design
Record particle-size range, fines content, shape, hardness, abrasiveness, friability, stickiness, moisture, temperature and hazard classification.
Large or fragile particles may need an inlet and rotor arrangement that reduces shearing at the housing edge.
Abrasive products shift attention toward rotor tip speed, replaceable wear surfaces and clearance growth.
Sticky products need a credible release and cleaning strategy rather than a hopeful coating note on the quotation.
Pressure, leakage and thermal clearance
Airlock duty: Define normal and maximum pressure differential, conveying direction and the acceptable leakage rate.
Leakage affects blower demand and can push upward through the inlet, reducing pocket filling.
Temperature changes rotor-to-housing clearance, so the design basis must cover product, ambient and upset conditions rather than one nominal value.
Do not infer explosion isolation, flame-barrier performance or hazardous-area suitability from the generic term “airlock”; those functions require the exact tested configuration and current certification.
Turn the video into a procurement checklist
Ask the supplier to state the selected valve family, pocket volume, assumed fill factor, speed range, leakage basis, materials of construction, rotor and seal design, drive margin, access method and operating envelope.
Define measurable acceptance criteria for solids rate, leakage, temperature, vibration, cleanability and product damage where they matter.
Continue with the detailed rotary valve sizing guide, compare alternatives on the Rotary Valves technology page, and review the Prater Industries company profile.
Related content
Continue exploring
Move from this page to the companies, videos and technical topics that add useful context.
Technologies
Guides
Comparisons
FAQs and tools
Connect with an expert
Ask about this video or solution
Tell us what you need. powderbulkvideos.com will route your inquiry with the page context attached.