MULTI-STAGE APPARATUS SOLD AS A UNIT FOR MOVING AIR (INCLUDING FANS), USING THE FLOWING AIR TO ASSIST IN SEPARATING DUST AND LIGHTER PARTICLES FROM HEAVIER GRANULAR MATERIAL (INCLUDING GRAVITY SEPARATORS, DESTONERS, ASPIRATORS), AND CLEANING THE DUST AND PARTICLES FROM THE FLOWING AIR AND SMOOTHING SUCH AIR FLOW FOR REUSE (INCLUDING CYCLONE SEPARATORS, PLENUMCHAMBERS, AND FILTERS), AND PARTS THEREFOR