Batch processing of particulate solids with automated control equipment is thought to have begun in the early 20th century and was initially based on the processing of grains and other basic, easy-to-process bulk foodstuffs. Initially, development was slow because there was little understanding or experience of how to manage product/system demands.

It is hypothesized that airlocks may have emerged as an obvious and simple solution for the controlled powered evacuation of storage tanks.

Over the decades, various terms have been adopted to describe this type of valve for this purpose: Rotary Airlock, Air Lock, Star Feeder, Rotary Valve, Rotary Feeder, and Vane Feeder. Some remain in use today, but Airlock is the most widely adopted generic term.

The wider development of systems engineering and feeders was slow until the 1950s, when bulk material processing began to become a much more knowledge-based, comprehensive and accepted industry in its own right, and the operating needs rapidly became much more widespread and demanding.

Despite their apparent simplicity, Airlocks have evolved to offer a variety of functional uses:
Offers the ability to control product flow rate to the required value (fixed or variable). Provides a gas pressure difference between inlet and outlet (air lock function). Acts as an explosion prevention device. Acts as an ‘Autonomous Safety Device’ for explosion and flame containment. Acts as a process isolator/barrier.

In addition to meeting any or combination of these requirements, Air Locks often handle the convenient handling of delicate or difficult materials in industrial processes that are affected by process, environmental and legal requirements.

Although now considered a well-developed, efficient and reliable piece of industry equipment, Air Locks continue to face challenges brought about by the evolving industry, new products required by the process, expanding customer needs and increasing legislation.

Air Locks are an important part of the bulk solids industry. The most remarkable feature of the Air Lock is that their design is so simple and yet so efficient that no other Air Lock can come close to replacing them and it looks set to remain so for the foreseeable future.