Avoid common duct-design flaws
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Wood Magazine

Avoid common duct-design flaws

Hand holding metal pipe
Enlarge Image
This reducer connects to corrugated
hose or narrower duct. Connecting
clamps let you reconfigure this type of
metal duct.
White pipe showing air flow, 3 photos together, use all three as one
Enlarge Image
3 illustrations of dust collectors, use as one as set up
Enlarge Image
The 90° elbows in the dust-collector
setup (top) add turbulence and
resistance. Two 45° bends
(center) reduce resistance, but a
straight run into the inlet port (bottom)
works best.

To avoid common duct-design flaws:

DO use the largest ductwork that fits your collector. Just because a tool comes with a 4" dust port doesn't mean you should use 4" main ducts or drops. Instead, look at the intake port sizes for the collectors you're considering. Most cyclones have intake ports of 6" to 8", and some two-bag collectors have 5"- or 6"-diameter intakes, so consider at least a 5" main duct. Tapered reducers, like the one below, change duct diameters with minimal static-pressure loss.

DO smooth out sharp curves. Think of air molecules as fast-moving cars on a freeway. Both change direction faster on a sweeping curve than a 90° turn. The PVC tee shown at near right adds more airflow resistance than the metal dust-collection pipe's gradual bend.

DON'T overuse flex hose. Corrugated tubing creates three times more static-pressure resistance than the same length of smooth pipe. Use just enough to link a tool to its drop pipe.

DO eliminate bottlenecks near the collector. (See "Give dust a straight shot to the collector" below.) Instead of two 90° bends, use two 45° bends. Better still, raise the collector until the main duct leads straight into the inlet.

DON'T create long duct runs. A single duct of 30' or more that wraps around more than two walls of a shop reduces air velocity and increases the risk of dust buildup. Instead, hang one shorter main duct, with diagonal branches leading to the tool drops.



Wood Magazine