How Do Rotary Airlocks Work?

If you’re not familiar with the conveying industry, you might not understand the importance of rotary airlocks. In this post, Carolina Conveying is here to change that.

Rotary airlocks are meant to prevent the loss of air and handle vital functions of a conveying system. Let us introduce you to what exactly rotary airlocks are, how they work, and their uses.

How Do Rotary Airlocks Work?

Rotary airlock valves are rotary valves used in conveying systems that need to isolate the system from pressure or allow air into the system, and they’re often called rotary airlock valves, rotary feeders, rotary valves or, as we know them, simply rotary airlocks. They are most commonly used in pneumatic conveying systems where air is the medium of conveying.

While acting as a lock, rotary airlocks also perform vital material handling functions. These components are critical to the efficiency of the machine and system as a whole. Basically, if conveying systems need to isolate the system from pressure or allow air into the system at a controlled rate, rotary airlocks are used – especially when air is the medium of conveying. 

Remember this: not all rotary valves are rotary airlock valves, but all rotary airlocks are rotary valves. Keep reading and we’ll get into more about how rotary airlocks work and what exactly they’re used for. 

What you’ve got to know is that rotary airlocks are useful tools that assist with the efficiency and overall effectiveness of conveying systems around the world. 

In this blog, we’re going to continue to discuss rotary airlock valves in depth. Let’s get started!


Equipment for Conveying Systems

Rotary airlocks are equipment used in conveying systems to ensure that particles move between bins and chambers without loss of pressure. They are designed with a rotary valve, which controls the transfer of air, and a screen or grate, which filters out particles. This ensures that the flow is continuous, and no particle remains in the air or chamber for longer than necessary. 

In a rotary airlock, you can find a rotary valve – and this controls the transfer of air through a screen or grate, and this screen/grate filters out particles. Because the screen/grate is porous, the flow is continuous and no particle remains in the chamber for longer than what’s necessary to the process. 

Rotary airlocks are available in different types and designs, depending on the application and needs. Some common types of rotary airlock valves include ball valves, diaphragm valves, check valves, butterfly valves, and rotary valves. Each has its own unique features and functionality, so it’s important to consider factors such as material type and size before selecting an airlock for your conveying system needs. 

Overall, rotary airlocks are reliable tools that can be used to improve conveying system efficiency and effectiveness.

Rotary Airlock Valves

Some common types of rotary airlock valves include ball valves, diaphragm valves, check valves, butterfly valves, and rotary valves. Each of these valves has its own special function and features so, before you choose one, it’s important to understand both the purpose it’s being used for and the components that make that valve unique. 

Consider the valve’s material and size before choosing an airlock for the needs of your system – this will ensure that you get the best result possible. 

standard duty rotary airlock valve

Rotary Airlock Ports

During operation, you’ll notice that the vanes (metal blades) of a rotary airlock valve rotate and, as they do, pockets form between them. In those pockets, the materials that are being handled will enter through the inlet port. Then, they’ll rotate around inside the valve and exit through the outlet port. 

Air is sealed between the inlet and outlet ports. This allows materials to travel down through the valve from the inlet to the outlet port, all the while airflow is restricted. Thanks to constant air pressure between both ports, material moves continuously – but the pressure or vacuum difference must be maintained in order for the airlock to function properly. 

Rotary Airlock Functions

Rotary airlocks are used in industrial processes as barriers to control the flow of material into and out of systems. They act as a barrier between two pressurized systems, allowing one-way flow of material. 

This creates a seal between two systems, preventing dust or gas from entering the process. Rotary airlocks save energy by maintaining proper pressure levels in each system, which prevents costly air leaks and noise. The rotary movement of the valve also reduces the chance of pneumatic shock or injury to workers.

Rotary Airlock Damage

Rotary valves are not indestructible. Like any other piece of machinery, wear and tear is possible after some time. You’ll notice that wear and tear to the rotor, housing, or both components is the leading cause of airlock valve failure. 

When it comes to processing abrasive materials, doing so can cause cumulative damage to the surfaces inside the valve, which can create degradation over time. 

When materials get trapped between two surfaces moving in different directions, the rotary airlock might also experience surface drag abrasion. Surface drag abrasion can also occur when any surface-on-surface contact occurs between the two planes, especially when it contains two abrasive materials. 

There’s also something called pneumatic assisted abrasion, a common issue with rotary airlocks, that occurs when turbulent air (also called ‘blow-by’) develops at the outlet port. This air is misdirected and it can cause not only a loss of efficiency, but problems with the flow of material between the inlet and outlet ports. The ‘blow-by’ air can also carry abrasive particles with it, and these particles cause damage to valve components that would not have been affected otherwise. 

Types of Rotary Airlocks

The heavy duty rotary airlock is designed to handle large volumes of material and provide a tight seal between two different areas. It does this by rotating between two stations, with each one being tailored for specific storage needs. 

There are three common types of rotary airlock valves – blow-thru, NFPA, and heavy duty. In this section, we’ll extrapolate on these types and what tasks they specialize in. 

Heavy Duty Rotary Airlock

The heavy duty rotary airlock is called ‘heavy duty’ for a reason. It’s designed to handle large volumes of material while providing a tight seal between two different compartments. In order to make this happen, it rotates between two stations that are both tailored to specific storage needs. 

This type of airlock reduces the dust released into the atmosphere, which is great for the health and safety of employees. They also maintain the pressure and temperature within a storage facility and can reduce energy costs because of that. 

Heavy duty rotary airlocks make sure that the right amount of material is released at the right time. Because of this, they are often used to store sensitive or hazardous materials. 

These airlocks are extremely versatile and incredibly helpful in storage facilities. 

BLOW-THRU Rotary Airlock

The BLOW-THRU Rotary Airlock is a reliable and efficient way to control the flow of material from storage bins or hoppers. It provides a dust-free, uniform discharge of material while preventing back pressure build up in the system. 

The rotary airlock also helps maintain the necessary air balance within the storage container, ensuring that moisture and dust particles are kept out. 

In addition, it can be used to regulate airflow and pressure, helping to maximize efficiency and reduce energy costs. Overall, the rotary airlock is a valuable tool for efficiently managing storage systems.

blow thru rotary airlock valve

NFPA Rotary Airlock

Rotary airlocks are used for storage and transfer of materials, such as grains, powders, and pellets. They are dust-tight and provide a continuous seal between the hopper and bin during material transfer. They are designed to be heavy duty and withstand high pressure and temperatures, making them ideal for industrial applications. Rotary airlocks offer numerous benefits, including reduced energy use, improved process efficiency, and enhanced safety. They are cost-effective and easy to integrate into existing processes for improved efficiency. Overall, rotary airlocks are a useful tool for improving the efficiency of industrial operations.

NFPA Design Rotary Airlock

Rotary Airlock Assembly

In a rotary airlock valve, the rotor assembly consists of a set of blades that are welded to a rotary shaft. Sometimes, this is referred to as the ‘paddle wheel,’ or the impeller, or a flipper. 

A six-vane rotor has six metal blades that are attached to the shaft and, as you’d expect, an eight-vane rotor has eight – and the amounts continue. If a valve has more vanes, it tends to be better at sealing than a valve with less vanes. 

But there’s a downside. As the number of vanes increases on a valve, the size of the pockets between them gets smaller. When it comes to larger materials, or materials that tend to stick together or pack together when they’re compressed, a larger pocket size is ideal. 

Regarding heavy materials and those that flow quickly, these are not as likely to be affected by the number of vanes and pocket size between them. 

When you know what type of material you’ll be handling, talk to us at Carolina Conveying about the optimal setup that’s right for you. We can also help you figure out if you’ll need an open-end or a closed-end rotor. Typically, open-ended units are better for easily-flowing and non-abrasive materials, while closed-ended units are better for materials that may find trouble flowing in a smooth and uninterrupted manner. 

Parts of Rotary Airlock Valves

The shaft of a rotary airlock is typically made of stainless steel or another durable material that can handle high temperatures and high pressure – it should also be made of a material that does not easily corrode. The shaft is typically 2-8 inches in diameter. The seal is made of rubber or another type of shock-absorbent material that’s designed to be used in water processing applications. 

The valve is commonly made from stainless steel as well, or another material that is durable has low internal resistance – like plastic or glass. This material should also be able to withstand high temperatures and high pressure without becoming degraded. 

Rotary Airlock Flaps

There are two main types of rotary airlocks, and that’s the single flap and the double flap. Single flap airlocks have one flap that rotates in a full circle, and that flap allows material to move into or out of the container. Double flap airlocks have two flaps that operate in opposite directions. You’ll want to decide which is best for you based on the application it’s being used for. 

Frequently Asked Questions

What is a rotary airlock and how does it work?

A rotary airlock is a mechanical device used to control the flow of material in and out of storage systems or other systems. It uses a system of rotating blades to create an airtight seal between two areas, allowing material to move through while preventing air from escaping. 

This design makes it possible for efficient movement of materials with minimal energy consumption. Rotary airlocks can be used in a variety of applications such as dust collection, material handling, and temperature control. They are also commonly used in pneumatic conveying systems, where they are used to feed material into a system at a consistent rate and pressure, which then allows for smoother operation of the system. 

When properly designed and installed, rotary airlocks can help prevent dangerous dust explosions and maximize safety in the workplace.


How many different types of rotary airlocks are there, and what makes them different from each other?

When it comes to rotary airlocks, there are two main types: single flap and double flap. Single flap rotary airlocks have one flap that rotates in a full circle, allowing material to move into or out of the container. 

Double flap rotary airlocks, on the other hand, have two flaps that operate in opposite directions. Rotary airlocks are used to regulate the flow of material into a storage or process container. Depending on the application and material being handled, different types of rotary airlocks can be used. For example, if dust is present in the material being transferred, a single flap rotary airlock may be necessary because dust will not escape through the gap between two flaps in a double flap rotary airlock.

About Rotary Airlocks

When it comes to rotary airlock valves, we can say they are the most sturdy and safest valve designs in the industry. They operate on simple but effective airlock principles, ensuring airlock and pressure differential safety in your conveying system. 

To get a rotary airlock valve of your own, contact Carolina Conveying. We’re here to support you with expert advice; reach out today