Avoid inferior metal duct that requires you to cut it to length and snap it together. This type of duct is time consuming to install because it requires you to seal all the seams with silicone and screw the components on the ends with sheet metal screws. Another disadvantage is the rough internal seams and crimped ends that unavoidably increase
static pressure.
Figure 10. Examples of metal pipe and
components.
Plastic Duct
Plastic duct is also a popular material for home shops. One problem with using plastic is that it is less efficient per foot than metal. The popularity of plastic duct is due to the fact that it is an economi- cal 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 is the inherent danger of static electrical build-up, which can lead to fire or explosion if not
correctly grounded.
Figure 11. Plastic duct and components. G5954 5HP Dust Collector
Flexible Duct
Flexible hose is generally used for short runs, small shops and at rigid duct-to-tool connections. There are many different types of flex hose on the market today. These are manufactured from materials such as polyethylene, PVC, cloth hose dipped in rubber and even metal, including steel and aluminum.
Figure 12. Example of flexible metal duct.
The superior choice here is metal flex hose that is designed to be flexible, yet be as smooth as possible to reduce static pressure loss. There are also many kinds of plastic flexible hose, such as non-perforated drainage type hose and dryer vent hose. Drainage type hose, while being economi- cal, does not quite have the flexibility 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 sys- tem. We DO NOT recommend using dryer vent hose in your dust collection system.
If using flex-hose, you should choose one of the many types that are designed specifically for the movement of solid particles, i.e. dust, grains and plastics. However, the cost of specifically designed flexible duct can vary greatly. Grizzly offers polyethylene hose, which is well suited for the removal of particulate matter, especially saw- dust, since it is durable and completely flexible. Polyethylene is also very economical and avail- able in a wide variety of diameters and lengths for most applications.
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