A dilute-phase transfer system suspends individual powder particles in a high-velocity air stream (15-35 m/s) at low solid-to-air ratios (1:1 to 15:1 by weight) — conveying 5 kg/h to 50 t/h over distances of 5 m to 500 m using vacuum (-0.2 to -0.6 bar) or positive pressure (0.3-1.5 bar). Ideal for free-flowing non-fragile powders (flour, sugar, starch, cement, polymer pellets), it provides the highest transfer rates of all pneumatic conveying modes with the simplest pipeline design and lowest equipment cost.

A roots blower or centrifugal fan generates the conveying airstream; a rotary valve or venturi injector introduces powder into the pipeline at the pickup point. Individual particles are suspended and transported as a dilute cloud to the destination filter receiver — where they separate from air by inertia in a cyclone or drop-out box. Air exits through a baghouse or HEPA filter before the blower return or atmosphere exhaust. Long-radius bends (R = 10x pipe dia minimum) reduce particle-wall impact velocity. VFD on blower motor adjusts air velocity to match product density and pipeline length — maintaining suspension without saltation (particle settling) throughout the transfer.