Material Selection
As shown in Figure 21, there are several differ- ent options to choose from when deciding on a duct material. Variables such as ease of use, cost, availability, and your specific shop, all play a part in determining the best option for you.
METAL DUCT
Metal duct comes in many varieties. Stove pipe, heating/ventilation duct and duct made espe- cially for dust collection are all options. Advantages of metal duct are its conductivity and that it does not contribute to static electri- cal charge build-up. However, static charges are still produced when dust particles strike other dust particles as they move through the duct. Since metal duct is a conductor, it can be grounded quite easily to dissipate any static electrical charges. However, metal duct is gen- erally more expensive than plastic duct and it is not usually airtight unless specifically manufac- tured for dust collection. Specially manufac- tured metal duct, on the other hand, is quite expensive. Metal duct is also generally more difficult to cut and assemble.
FLEXIBLE HOSE
Flexible rubber hose, polyethylene, plastic flex-hose and other flexible ribbed hose are generally used for short runs, small shops and at rigid duct-to-tool connections. Woodstock offers a large variety of flexible hose with many diameters and lengths to choose from. The fig-
ure below shows some options to consider.
There are also many kinds of pure plastic flexi- ble hose, such as non-perforated drainage type hose and dryer vent hose. Drainage type hose, while being economical, does not have the flex- ibility required for dust collection. The inside of the duct is also deeply corrugated and can increase the static pressure loss by as much as 50% over smooth wall duct. Dryer vent hose, while being completely flexible, is non-resistant to abrasion and has a tendency to collapse in a negative pressure system.
Woodstock flex-hose is designed specifically for the movement of solid particles, i.e. dust, grains and plastics. It is well suited for the removal of particulate matter, especially sawdust, since it is durable and completely flexible.
RIGID PLASTIC DUCT
The popularity of plastic duct is due to the fact that it is an economical and readily available product. It is also simple to assemble and easily sealed against air loss. The primary disadvantage of plastic duct for dust collection, whether black ABS or white PVC and even rubber or polyethyl- ene flex-hose, is the inherent danger of static electrical build-up.
Accessories
See your local Woodstock Dealer for the Model W1049 Dust Collection Separator shown in Figure 22. The Model W1049 turns your dust col- lector into a 2-stage collection system.
