Typical bulk materials, which can be conveyed pneumatically, are powders, pellets, granules and irregularly shaped particles smaller than 20 mm [0.75 in]. The majority of pneumatically transported materials have a bulk density between 0.1 to 1 kg/dm3 [5 to 100 lb/ft3].
Pneumatic conveying systems can be built using pressure or vacuum. The most commonly applied pneumatic conveying mode is dilute phase conveying where particles are airborne. Depending on the size, shape and weight of the particles, the gas velocity will range from 4 to 40 m/s [4,000 to 8,000 ft/min].
Dilute phase conveying systems will work reliably for a wide range of materials with different characteristics, such as high bulk density, cohesive properties or extreme particle shapes. Due to the high air velocity, material degradation or wear might be a factor.