Recommended velocity ranges are shown below, they can vary with the specific qualities of the particle (size, dampness etc) and the duct design. 

SUBSTANCE	Ms-1
Gases –Non Condensing	No Min Limit
Fume	5 - 10
Fume – Aluminium
Fume – Zinc
Smoke
Fume - Welding	10 - 12.5
Fine Dust – Cotton Fly	10 - 15
Fine Dust – Lint
Fine Powders
Litho Powder
Wood Flour
Bakelite Moulding Powder	12.5 - 20
Cotton Dust
Dust & Powders with Low Moisture Content
Fine Rubber Dust
Fine Wood Shavings
Jute Lint
Leather Shavings
Plastic Dusts
Soap Dust
Asbestos Fibres	17.5 – 20
Brick Dust
Buffing Lint
Cement Dust
Coffee Beans
Food Powders
Foundry Dust
General Material Handling
Granite Dust
Grinding Dust
Limestone Dust
Normal Industrial Dust
Pottery Clay Dust
Rock Dusts
Sawdust
Shoe Dust
Silica Flour
Wool Jute Dust (Shaker Waste)
Asbestos Chunks	22 – 25
Buffing Lint (Sticky)
Dusts which tend to agglomerate
Heavy & Moist Dust
Lead Chippings
Metal Turnings
Moist Cement
Paint Spray Particles
Quick Lime Dust