Operators seeking to reduce dust generation or save energy frequently turn down blower VFD speed. When gas velocity drops below Rizk's saltation threshold ($v_g < v_{salt}$), solids fall out of suspension into moving dunes. Friction spikes exponentially, the dunes lock against pipe walls, and within seconds the entire 100-meter line plugs solid with tons of compacted powder. Clearing a plugged pneumatic line requires maintenance crews to disconnect flanges and hammer or clean every pipe spool manually for two days.

In plastic compounding plants, conveying polyethylene or nylon pellets above 20 m/s causes intense localized friction heating when pellets impact standard smooth stainless steel elbow walls. Pellets melt at the point of contact, smearing a micro-film of polymer that peels off into long, hair-like plastic streamers (angel hair). These bird-nest tangles blind receiving cyclone screens, choke extruder feed hoppers, and contaminate finished molded automotive parts. Using grooved shot-peened pipes or vortex chamber (gamma) elbows is essential.

When conveying abrasive minerals (silica sand, fly ash, alumina, or clinker), particles cannot negotiate standard 90° pipe bends and slam directly into the outer elbow wall at full velocity ($Erosion propto v_g^{2.5 - 3.5}$). A standard Schedule 40 steel elbow will blow out cleanly within weeks, blasting abrasive dust into factory air and creating severe safety and combustible dust hazards. Designers must specify ceramic-tile-lined elbows, basalt lining, or blind-tee dead-end dirt-box elbows.

In positive-pressure systems, the pipeline operates at 40 to 80 kPa gauge while the supply bin above the rotary airlock is at atmospheric pressure. Rotor blade-to-housing clearances allow high-pressure conveying air to leak upward (blowby air). If this leakage exceeds 15% of feeder volume, the upward air blast aerates and fluidizes fine powders in the inlet throat, choking gravity feed into the rotor pockets. Solid feed rate collapses by 60%, destabilizing downstream reactors. Feeder vent hoppers are mandatory.

High-velocity particulate collisions strip electrons, generating static electrical potentials exceeding 30,000 Volts across ungrounded pipe sections, sight glasses, and rubber flex sleeves. For organic powders (flour, starch, wood flour, sugar), a single electrostatic discharge spark exceeding the Minimum Ignition Energy (MIE ~ 10-30 mJ) detonates the aerosolized dust cloud inside the pipe or cyclone, initiating devastating secondary dust explosions that can destroy the entire facility. Continuous copper grounding straps across all flanges are legally required.