The rotary valve is the most used airlock valve on dust collectors. It works well for many applications but isn’t always the best solution. And while dust collectors usually collect “dust” they also collect larger particulates. Depending on the applications, large pieces such as wood chips, small rocks, Styrofoam, etc. can be collected in the dust collectors. And even if it is dust that is collected, the dust can agglomerate in the dust collector so large pieces fall into the airlock valve. And when the valve is a rotary airlock these larger pieces might jam or plug up the rotor.
When larger material is present a double dump valve (double flap) might just be the valve for you. The double dump valve uses two valves mounted one on top of the other to provide the airlock. When one is open, the other is closed. The valve opening is a large whole nearly the size of the valve ID which allows larger-sized material to pass through.