Rotary Valve for Cement, Fly Ash and Dry Powder Handling
Rotary Airlock Feeder for Silos, Hoppers, Dust Collectors and Pneumatic Conveying Systems
What Is a Rotary Valve?
A rotary valve is a bulk material handling device that uses a multi-pocket rotor to discharge powder or granules continuously from a silo, hopper, filter or process vessel. Material fills the rotor pockets at the inlet and is carried to the outlet as the rotor turns.
It may also be called a rotary airlock valve, rotary feeder, star discharge valve or airlock feeder, depending on whether the application emphasizes material feeding, discharge or limiting air leakage between connected equipment.
Key Features
✅ Continuous Material Discharge
The multi-pocket rotor transfers powder or granules continuously from the inlet to the outlet.
✅ Airlock Function
Close rotor clearances help limit air leakage and pressure equalization between connected equipment.
✅ Multiple Rotor Configurations
Open-end, closed-end and replaceable-tip rotors can be selected according to the material and duty.
✅ Customized Construction Materials
Cast iron, carbon steel or stainless-steel construction can be provided according to the application.
✅ Flexible Drive and Speed Control
Direct drive, chain drive and optional variable-frequency control are available according to the required feeding rate.
✅ Replaceable Wear Components
Rotor tips, seals, bearings and other wear parts can be selected for inspection and replacement.
How Does a Rotary Valve Work?
Material enters through the upper inlet and fills the pockets between the rotor blades. As the gear motor rotates the rotor, each pocket carries material toward the lower outlet, where it discharges into the downstream equipment.
Rotor pocket volume, rotational speed and filling efficiency determine the approximate volumetric output. The clearance between the rotor and housing helps restrict airflow, but the rotary valve is not a zero-leakage shut-off valve. Actual air leakage depends on the rotor clearance, pressure difference, rotor design and wear condition.
Available Rotor Types
| Rotor Type | Main Characteristics | Typical Application |
|---|---|---|
| Open-End Rotor | Simple construction and easier material release | General powder and granular discharge |
| Closed-End Rotor | Reduced direct communication with the end plates | Fine powder and applications requiring improved airlock performance |
| Replaceable-Tip Rotor | Individually replaceable or adjustable rotor tips | Cement, fly ash and abrasive powder |
| Customized Rotor | Rotor profile selected for the material and process | Sticky, hot, abrasive or special materials |
For abrasive powders, a replaceable-tip rotor may be selected so worn blade tips can be replaced without changing the complete rotor.
Proper rotor selection affects material flow, air leakage, wear rate and rotary valve service life. More information is available in this guide to rotary airlock valve principles and rotor design.
Housing Materials
| Housing Material | Typical Use |
|---|---|
| Cast Iron | General dry powder discharge |
| Carbon Steel | Cement, fly ash and mineral powder |
| Stainless Steel 304 | Cleaner or mildly corrosive applications |
| Stainless Steel 316 | More corrosive or application-specific environments |
Material selection depends on abrasiveness, corrosion, temperature, cleaning requirements and expected service life.
Typical Technical Specifications
| Item | B150 | B200 | B300 | B400 | B500 |
|---|---|---|---|---|---|
| Nominal Inlet Size | 150 × 150 mm | 200 × 200 mm | 300 × 300 mm | 400 × 400 mm | 500 × 500 mm |
| Reference Capacity | 3-8 m³/h | 9-15 m³/h | 16-30 m³/h | 32-40 m³/h | 40–60 m³/h |
| Reference Rotor Speed | 10–30 rpm | 10–30 rpm | 10–30 rpm | 10–30 rpm | 10–30 rpm |
| Reference Motor Power | 0.55 kW | 0.75 kW | 1.5 kW | 2.2 kW | 4 kW |
| Housing Material | Cast Iron / Carbon Steel / SS304 | Cast Iron / Carbon Steel / SS304 | Cast Iron / Carbon Steel / SS304 | Cast Iron / Carbon Steel / SS304 | Cast Iron / Carbon Steel / SS304 |
| Rotor Type | Customized | Customized | Customized | Customized | Customized |
| Drive Type | Direct / Chain Drive | Direct / Chain Drive | Direct / Chain Drive | Direct / Chain Drive | Direct / Chain Drive |
| Suitable Material | Powder / Granule | Powder / Granule | Powder / Granule | Powder / Granule | Powder / Granule |
The values above are for preliminary model selection only. Actual capacity depends on rotor pocket volume, rotor speed, filling efficiency, material bulk density, flowability, aeration and system pressure.
Applications and Installation Positions
✅ Below cement and fly ash silos
✅ Below bag filters, cyclones and dust hoppers
✅ Above screw conveyors and other feeding equipment
✅ Before suitable pressure or vacuum pneumatic conveying lines
✅ In cement, fly ash, lime and mineral powder handling systems
A slide gate valve is normally installed upstream when the rotary valve must be isolated from the silo or hopper during maintenance.
Where hardened lumps may enter from the silo, a lump breaker or suitable screen should be installed upstream. A rotary valve should not be used as a lump-crushing machine.
How to Select a Rotary Valve
A rotary valve should not be selected by the silo outlet size alone. Please provide:
✅ Material name, bulk density and particle size
✅ Flowability, moisture, abrasiveness and temperature
✅ Required capacity
✅ Gravity discharge, pressure or vacuum application
✅ Installation position, system pressure and inlet/outlet dimensions
✅ Power supply, control requirements and site drawing
The valve size, rotor type, speed, internal clearance, shaft seals, motor power and construction material must be confirmed according to the actual operating conditions.
For a rotary valve used in pneumatic conveying, the operating pressure, pressure difference, rotor clearance, shaft sealing and acceptable air leakage must be confirmed before production.
Manufacturing and Inspection
LVRUI manufactures each rotary valve according to the confirmed material data, operating pressure, interface dimensions and approved production drawing.
Before shipment, the main checks include:
✅ Housing and flange dimensions
✅ Rotor, shaft, clearance, seals and bearings
✅ Drive assembly, rotation direction and no-load operation
✅ Surface coating, marking and packing
LVRUI provides technical drawings, installation instructions and remote technical guidance. Installation is completed by the customer or its local contractor.
Rotary Valve FAQs
What is a rotary valve used for?
A rotary valve continuously discharges powder or granules from a silo, hopper, dust collector or process vessel through a rotating multi-pocket rotor. It can also provide approximate volumetric feeding to downstream equipment.
Is a rotary valve the same as a rotary airlock valve?
They generally refer to the same equipment category. “Rotary valve” is the general name, while “rotary airlock valve” emphasizes limiting airflow between areas with different pressures. It restricts air leakage but is not a zero-leakage shut-off valve.
Can a rotary valve handle cement and fly ash?
Yes. Rotary valves are commonly used for cement, fly ash, lime powder, limestone powder and other compatible dry bulk materials. Rotor type, clearance, shaft seals and construction material must be selected according to abrasiveness and operating conditions.
Can a rotary valve be installed below a dust collector?
Yes. It can be installed below a bag filter, cyclone or dust hopper to discharge collected powder while helping limit uncontrolled air entry. System pressure, dust properties, rotor clearance and shaft sealing must be considered during selection.
Can a rotary valve provide accurate dosing?
A rotary valve provides approximate volumetric feeding based on rotor pocket volume, speed and filling efficiency. High-accuracy dosing normally requires downstream weighing equipment or a closed-loop weighing and control system.
What information is required for a quotation?
Please provide the material, bulk density, particle size, required capacity, temperature, system pressure, installation position, inlet and outlet dimensions, power supply and site drawing.
Request a Customized Rotary Valve
Send LVRUI your material, required capacity, pressure conditions, connection dimensions and site drawing. We will recommend a suitable rotor, shaft seal, drive and valve configuration.
✅ Gravity discharge or airlock application
✅ Customized rotor and shaft-seal design
✅ Direct or chain drive
✅ Technical drawings and remote guidance