ALC - Aerodyne

When you have a combustible dust, not only does your dust collector require to be protected against a deflagration, but the airlock must contain the event.  NFPA-69 allows the use of a rotary valve as long as the following:

The Vacu-Valve is a low cost alternative to a rotary valve.  There are no motors, pneumatics, or moving parts as it operates by using the system vacuum above to seal the sleeve.  This is typically from a cyclone, baghouse, or cartridge collector.  Since the sleeve is split, gravity will slowly pull the solids down through the sleeve until they exit the sleeve and fall into the collection hopper.  As you can see from the description, not all solids will easily pass through this.  The ideal particulate would be sand.  It’s small, spherical shape and the density allows it to easily pass through the valve.  It doesn’t bridge easily.

An engineering company is working with a peanut supplier on how to control the pneumatic peanut shell waste. The peanut company is currently using six cyclones in various sizes to dispose of the waste. The company, however, by not having any airlock valves under the cyclone, are carrying through some dust into a clean outlet. The company, looking to fix this problem, turned to Aerodyne.