This is a great question because they’re also called airlocks (or rotary airlock valves, or rotary airlock feeders) — just to make it extra confusing. The catch-all term is rotary valve, which is what we use most often.
The exact term changes depending on how the valve is used. Anything with the word “airlock” in the name is used to maintain a pressure differential between two separate compartments. Feeders are more about controlling the rate of material flow from one place to the next. If a valve does both, you would call it a rotary airlock feeder.
At ACS Valves, we have a lot of multifunctional rotary valves that can serve any of these roles, as well as more specialized valves for airlock or feeding/metering purposes. If you’re not sure what you need, give us a call and we’ll help you figure it out!