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How to Design a Dust Collector Duct System

Step One: Layout the Machinery of Your Shop

What are the limitations of your workshop or space? Keep in mind the ceiling height, obstructions, electrical service, etc.

• Place machines that require the largest CFM (cubic feet per minute) of airflow closest to the dust collector.
• To determine CFM, measure the diameter of dust ports and use this chart to estimate your machines CFM requirements.

Note: If a machine has multiple dust ports, the total CFM is the sum of all ports.


Example: if your woodworking machine has a 3” port you can assume that it requires approximately 220 CFM
When determining the size of your ducting, begin at the machine furthest away from your dust collector and work your way backwards.

Step Two: Draw a Top-Down View Sketch (to Scale) Of Your Machines and Dust Collector

For accuracy, use grid paper and indicate the exact location of each dust port. Include the CFM requirements for each dust port.

Step Five: Determine The Size Of your Ducting

Start at the machine that is farthest away from the collector (machine one) and work your way back. Determine the diameter of CFM requirements at machine one. For instance, if the machine has a CFM of 395, 4" ducting will be required.

Continue to the second machine. If machine two has a dust port that is 3" when it connects to the main duct (where the 4" duct from machine one connects), you will add the CFM from the chart:
220 + 395 = 615 which would be a 5" duct

The branch would be sized at 5-3-4, with 5" being the largest reducing to 4" with a 3" branch going out the side at 30 degrees.

It will require a 60-degree elbow to make the run perpendicular.


Nordfab QF Ducting vs. Flanged Ducting

Nordfab quick-fit is a clamp-together, modular ducting system where each section of duct has a rolled edge that is easily joined with a simple and tool-free clamp.

• Installs in less than 1/2 the time of standard flanged duct systems.
• Can be taken apart and reconfigured quickly and easily.
• Aligns perfectly to ensure long runs are even and have minimal static pressure loss.

Nordfab ducting can be integrated with existing ductwork to enhance efficiency and prevent leakage or installed as a brand new system. Our clamp-together, modular ducting systems are ideal for the following industries and/or applications:

Flanged ducting is a method in which two pieces of duct are joined using metal flanges. This process requires flanges to be fitted over each end of the pipe, the edge of the duct is then vanstoned to keep the flange in place, and lastly, flanges are bolted together to join pieces.

• Construction is 2x as long as clamp-together ducting.
• It's extremely difficult to move or reconfigure flanged ducting systems. In most cases, flanged ducting is throw away.
• If flanges are not placed perfectly, duct segments will not align resulting in an unprofessional appearance and higher static pressure loss.

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