Range of Minimum Duct Design Velocities

Minimum transport velocity represents the velocity that must be maintained in the duct system to ensure that particulate contaminants do not settle to the bottom of the ducting. Below is a range of minimum duct velocities for a variety of contaminants.

The following data is offered as a guideline only. Additional dust characteristics, machinery constraints, and other system requirements can affect performance and must be considered.

Nature of Contaminant   Contaminant Examples  

Design Velocity (fpm)

Smoke, vapors, gases   All smoke, vapors and gases  

 Any desired velocity

(economic optimum velocity usually 1000-2000 fpm)

Fumes   Welding   2000-2500
Very fine light dust   Cotton lint, wood flour, litho powder, toner powder, paint pigments   2500-3000
Dry powder & dusts   Cotton dust, shavings (light), leather shavings, fine rubber dust, Bakelite molding powder dust, jute lint, soap dust, plastics dust    3000-4000
General industrial dust   General material handling, grinding dust, coffee beans, buffing lint (dry), wool just dust (shaker waste), shoe dust, granite dust, silica flour, brick cutting, clay dust, cement dust, brick dust, gypsum dust, foundry (general), limestone dust, packaging and weighing asbestos dust in textile industry, animal feed products    3500-4000
Heavy dusts   Sawdust (heavy and wet), wood blocks, metal turnings, sand blast dust, foundry tumbling barrels and shake-out, hog waste, brass turnings, cast iron boring dust, lead dust    4000-4500
Heavy or moist   Lead dusts with small chips, moist cement dust, asbestos chunks from transite pipe cutting machines, buffing lint (sticky), quick-lime dust, wood waste (transport systems)    4500 and up

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