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 Range (m/s)

Clean air   Filter to fan ducts  

 15 - 18

Smoke, vapors, gases    All smoke, vapors and gases   10 - 12
Fumes   Welding   15 - 18
Very fine light dust   Cotton lint, wood flour, litho powder, toner powder, paint pigments   18 - 20
Dry powder & dusts   Cotton dust, shavings (light), leather shavings, fine rubber dust, Bakelite molding powder dust, jute lint, soap dust, plastics dust   18 - 20
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    18 - 22
Heavy dust   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   20 - 24
Heavy or moist dust   Lead dusts with small chips, moist cement dust, asbestos chunks from transite pipe cutting machines, moulding machines, CNC Routers, hogging, hammer mills, buffing lint (sticky), quick-lime dust, wood waste (transport systems)    25 - 32

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