A rotary valve, often referred to as a rotary airlock or rotary feeder, is an essential component in pneumatic conveying and bulk material handling systems. Its primary function is to serve as an airlock, efficiently discharging dry, free-flowing granular materials—such as plastic pellets, grains, seeds, granules, and powders—from a hopper or bin into a pressurized or vacuum-based conveying line. By doing so, it maintains a critical pressure differential, preventing air from flowing backward through the system, which would disrupt material flow and reduce efficiency.
The valve's operation is straightforward yet highly effective. It consists of a rotor with multiple blades (vanes) mounted inside a precision-machined housing. As the rotor turns, the pockets formed by the vanes fill with material from the inlet at the top. The rotation then carries this material to the bottom, where it is gravity-discharged through the outlet. This continuous, pulsation-free action ensures a consistent and controlled feed rate, which is vital for processes requiring precise dosing or batching.
Key advantages of rotary valves for granular handling include their robust construction, often from cast iron or stainless steel, which provides durability and abrasion resistance. Many designs feature adjustable clearances and replaceable wear tips to extend service life when handling abrasive materials. Furthermore, they are versatile; models are available for various applications, including high-pressure environments, high-temperature duties, and for handling fragile granules that require gentle handling to prevent degradation.
In summary, the rotary valve is a workhorse of industry, providing reliable, efficient, and controlled transfer of granular materials while ensuring the energy efficiency and operational integrity of the entire pneumatic conveying system.