- 1 What is a Rotary Valve?
- 2 Types of Rotary Valves
- 3 Operating Speed of Rotary Valve
- 4 Functions of Rotary Valves
- 5 Components of Rotary Valve
- 6 Limitations of Rotary Valves
- 7 Applications of Rotary Valve
What is a Rotary Valve?
A rotary valve (also known as a rotary-motion valve) is a type of valve in which the rotation of a passage in a transverse plug controls the fluid flow through the connected pipelines. The common stopcock is the simplest form of the rotary valve. Rotary airlock valves are also known as rotary feeders, rotary valves, or just rotary airlocks.
Types of Rotary Valves
The rotary valves have the following major types:
- Quick-Take-Apart (QTA) Series Rotary Airlock
- BAV Rotary Airlock Valve
- Dust Collector Series
- Abrasion Resistant Rotary Airlock Valve
- Heavy-Duty PAV Series
- Blow-Thru Rotary Airlock Valve
1) Quick-Take-Apart (QTA) Series Rotary Airlock
For material handling applications that require quick cleaning or frequent removal of the rotary valve internal components, Prater’s Quick-Take-Apart (QTA) Series Rotary Airlock is also designed for safe, tool-less removal of the rotor and end plate as one single piece.
Like the BAV series, the QTA is designed to increase production efficiency by eliminating the often time-consuming step of “gapping” the rotor during reassembly, but in a package without the rails when space is limited. The QTA’s are constructed in cast iron or stainless steel. 6” and 8” models are available. The QTA is ideal for those applications that require frequent cleaning and/or changeover.
2) BAV Rotary Airlock Valves
For material handling applications that require quick cleaning or frequent removal of the rotary valve’s internal components, Prater’s BAV Series Rotary Airlock is ideal.
The BAV Series is designed with a demountable rotor and rail system for safe, tool-less removal of the end-plate and rotor as one piece. These standard BAV features increase production efficiencies by:
- Fast and easy disassembly for maintenance, cleaning, and inspection
- Eliminating the time-consuming step of “gapping” the rotor during reassembly
- Protects against operator strain and part damage from handling the components in awkward or compromised locations
- Self-centering the rotor for quick reassembly
The BAVs are constructed in stainless steel. 6″, 8″, 10″, and 12″ models are available for the drop-through style and 8″, 10″ and 12″ models for the blow-thru. BAV Series Rotary Airlocks are ideal for applications requiring frequent cleaning or changeover.
3) Dust Collector Series
The dust collector series rotary airlock valves are ideal for the applications to use at the discharge of material of dust collectors, hoppers. These types of rotary valves are designed for low-temperature minimal pressure differential applications.
Dust collector series rotary airlock valves provide air seals that do not feed at a specific rate. They are a heavy-duty design with eight blade rotors and an economical and precision machine.
Economical and budget-friendly, the standard heavy-duty design features eight-blade rotors, precision machining, and rugged cast iron housings. The Dust Collector Series rotary airlock valves can easily be configured for most application requirements.
4) Abrasion Resistant Rotary Airlock Valves
The Abrasion Resistant Rotary Airlock Valves are for applications one step beyond the Heavy-Duty PAV Series for highly abrasive or corrosive material handling needs.
The ceramic lined cast iron housing can withstand the most abrasive and corrosive products and applications. Simply, it is the most durable, wear-resistant rotary valve available and offers the solution to other rotary valves that wear out prematurely.
Engineered to achieve high performance with less maintenance, the Abrasion Resistant Rotary Airlock Valves are lined, then honed to maintain their precision tolerances. They will outperform any other types of rotary valves on the market.
5) Heavy-Duty PAV Series
Rugged and durable as its name, the Heavy-Duty PAV Series is a versatile rotary valve for displacing many dry, free-flowing powders from large bins into pneumatic systems and is designed to maintain a pressure differential up to +/- 15 PSI.
These valves are constructed from stainless steel or cast iron. They are heavy-duty PAV Series rotary airlock valves built for high-temperature applications, up to 500°F. For extreme applications to 1,000°F, high-temperature service kits are available.
Optional coatings (e.g., chrome, tungsten carbide, etc.) and construction materials are available to handle abrasive or corrosive materials. Companies of all sizes and types can look to the Heavy-Duty PAV Series rotary airlock if the material handling needs to transfer dry, bulk materials.
6) Blow-Thru Rotary Airlock Valves
As the name suggests, the Blow-Thru Rotary Airlock Valves are specifically designed and manufactured for processes requiring discharge into pneumatic conveying lines. Perfect for free-flowing materials, the innovative, larger vane pocket design handles up to 50% more volume.
More volume enables the rotor to operate at lower speeds, which increases efficiency and decreases wear. The Blow-Thru valves are engineered for minimal air leakage, a low-pressure drop, and less maintenance to ensure a higher return on investment.
Operating Speed of Rotary Valve
The operational speed of a rotary valve is determined with respect to the bulk density of the material and the size of the handled material because for high efficiency; it is important to run the rotor at the correct speed.
Functions of Rotary Valves
- The rotary valve is used for controlling materials flow rate to the required rate.
- In the inlet and outlet, it maintains differential gas pressure.
- It acts as an explosion or flame barrier.
Components of Rotary Valve
The rotary valve has the following major components:
- Rotor Bearing and Seal
The rotor shaft is attached to the drive mechanism from outside, which controls the rotation speed of the rotor and the direction of the rotor.
2) Rotor Bearing and Seal
Rotor bearing is provided for holding the rotor in place, and material is being sealed from inside of the valve housing through the bearing and the shaft seal.
It is the rotating part of the valve provided for material handling.
It is generally of cast iron construction for reducing the cost and imparting rigidity. Housing provides a protective pathway and inlet/ outlet ports in the valve.
Limitations of Rotary Valves
- It does not flow material; it just passes the material which falls into it.
- When the valve is being operated at high pressure, velocity erosion from fine abrasive material through clearance by leakage air.
- When the rotor speed is high, then efficiency is very low.
- Generally, rotary valves leak air when the system is being operated, resulting in poor performance.
- When the vent design is not done properly, then it well reduces the system and valve performance.
Applications of Rotary Valve
- Pneumatic conveyance
- Frequently cleaned/abiotic applications
- Changing the pitch of brass instruments.
- Most hydraulic automotive power steering control valves.
- Plastics manufacturing
- Controlling the steam and exhaust ports of steam engines, most notably in the Corliss steam engine.
- Abrasive product conveyance/metering
- Periodically reversing the flow of air and fuel across the open-hearth furnace.
- Pharmaceutical manufacturing applications
- Loading sample on chromatography columns.
- Chemical and food processing applications
- Some types of four-stroke and two-stroke