Dust Control Tips (Duct work, Vacuums, AFD, & Collection Systems)

Below are some helpful tips on dust control and dust management. As woodworkers and woodturners, we must be aware of the dangers of dust and know what steps can be taken to ensure a safe working environment. A proper dust collection system is what separates a good workshop from a great workshop. A good dust collection system will not only make your shop cleaner, but will also provide a healthier place to work. There are many strategies to help control dust. These include: dust masks, respirators, vacuums, dust collection systems, air filtration devices, ventilation systems, and enclosures to help isolate heavy dust producing machines.

Dust control tips including collection systems, duct work, air gates, masks, vacuums, fine dust, and filtration devices.

When deciding on how to control dust, the first question you need to ask yourself is who will use the area. If just one person will be working in the shop, then a dust mask or respirator may be the solution. However, if multiple people will be using the area whether for training or educational purposes, then a more elaborate system should be implemented which includes both primary and secondary dust collection. Primary dust collection involves capturing dust at the source (e.g., dust ports, dust hoods, and the canvas bag found on some portable power tools). On the other hand, secondary dust collection involves capturing dust once it has escaped the source and has become airborne.

Examples of secondary dust collection include air filtration devices and vacuuming dust off your shop floor. As shown in the dust control flow chart, a good approach to dust management typically involves using numerous approaches. Below are some ways to help control dust in your shop.

1. Consider venting dust outside.

Venting dust outside eliminates ALL fine dust. Even the best filters on the market do remove 100% of the dust. Venting outside can also be less expensive since a central dust collection system (cyclone, filters, and canister) would not be required. Drawbacks and warnings: If your shop is climate controlled, then venting can be expensive. Since the exhausted air has to be made up with outside air which will need to be either heated or cooled. Finally, venting can be very dangerous if you have gas fired appliances (furnaces or water heaters) or wood burning stoves. If outside air is not freely allowed in the shop, the flue gasses and smoke will be drawn downward into the shop.

2. Realize that power sanding typically produces the greatest amount of fine dust.

While all woodworking operations create some fine dust. Power sanding produces huge amounts of fine powder dust which can remain suspended in the air for hours afterwards.

3. Consider installing a dust collection system with a cyclone.

Dust collection units come in both one stage and two stage systems. Unlike one stage dust collectors, a two stage air collection system has a pre-collector or cyclone. Dust laden air enters this cone shaped cyclone and through inertia moves towards the outer wall. There the large chips and shavings lose momentum and fall into a drum below. Some manufactures claim their cyclones remove 99% of the dust before reaching the filter. The remaining fine dust passes through a filter which traps the smaller particulates. As shown in the figure below, a cyclone system can also be added to your vacuum.

Two stage dust collector with cyclone.
Two stage dust collector with cyclone.
A vacuum cleaner transformed into a two-stage dust collector.
A vacuum cleaner transformed into a two-stage dust collector.

4. Try to use either a “Central Run” or a “Diagonal Run”.

Central and diagonal runs use less ductwork and will have a more efficient dust collection system. On the other hand, the “Perimeter Run” typically requires longer runs and more turns in the ductwork. This additional ductwork and turns increase the risk of dust buildup and reduces air movement – consequently performance may suffer as a result.

Central run dust collector.
Central run.
Diagonal run dust collector.
Diagonal run.
Perimeter run dust collector.
Perimeter run.

5. Arrange your biggest dust producers closest to the dust collector.

This will help create a more optimal solution, since the amount of air volume will be larger on shorter runs. Of the two configurations shown below, the ductwork Configuration #2 would have a better performance since a belt sander typically produces more dust than a scroll saw.

Configuration 1.
Configuration 1.
Configuration 2.
Configuration 2.

6. Keep duct work as short and straight as possible.

Think of static pressure as the suction potential. For best results avoiding twists and turns. A wye branch gently merges two airflows into a single branch. However, even with a gentle wye merge, a single 5” (13cm) diameter fitting will lose the equivalent of 6 feet (1.8 meters) of straight pipe. Similarly, a 5” (13cm) 90-degree elbow will lose the equivalent of 9 feet (2.7 meters) of straight pipe.

“Wye” branch
“Wye” branch
90-degree elbow
90-degree elbow

7. Keep flexible hoses short for optimal dust control.

The corrugated inside surface of a flexible hose creates 3 times the air resistance as a smooth pipe. Specific example:
. The static pressure loss per foot for a 5” (13cm) straight duct is 0.05
. The static pressure loss per foot for a 5” (13cm) flexible hose is 0.15

Flexible duct.
Flexible duct.
Smooth duct.
Smooth duct.

8. Avoid using HVAC metal pipe (30-gauge or lighter) for ductwork.

This metal is too thin to withstand the pressure of a dust collector and may collapse if all air gates are closed. If using metal pipe for ductwork, most experts recommend using at least 26-gauge metal, or using steel spiral pipe which has ribs making it much stronger.

9. Use “Blast gates” or “Air gates” to help improve efficiency.

By turning off suction on machines not in use, you can achieve more suction on the machines currently being used.

Blast gate.
Blast gate.

10. Realize the “volume of air” is more important than “air velocity.”

Volume of air is typically measured in Cubic Feet per Minute (CFM). It is this measurement,
not air velocity or air pressure that is the key to removing fine dust particles.

Air-filtration Devices

An air-filtration device can gather airborne dust. The air-filtration device shown below has 3 speeds: allowing it to filter 550, 702, and 1044 cubic feet per minute (CFM). It can filter the air in a 20’ x 20’ x 8’ shop a dozen times per hour.

Air-filtration device
Air-filtration device

11. Position an air-filtration device in the best location for optimal dust control.

The optimal position for an air-filtration device is along the long wall – approximately 1/3 the distance from the short wall. This will help circulate the air throughout the shop.

Optimal location for a single air-filtration device.
Optimal location for a single air-filtration device.

12. Position a second air-filtration device along the opposite long wall.

The second AFD should be located approximately 1/3 the distance from the short wall. This second air-filtration device will help clean and continue the air circulation throughout the shop.

Optimal location for a second air-filtration device.
Optimal location for a second air-filtration device.

13. Never place smoke alarms in corners of a room.

When mounting a smoke alarm, the National Fire Protection Association (NFPA) [http://www.nfpa.org] recommends smoke alarms be mounted on the ceiling in the center of the room. This places the smoke alarm closest to all points in the room. “Dead air” spaces may prevent smoke from reaching the smoke alarm.

Avoid installing smoke alarms in the corners of a room.
Avoid installing smoke alarms in the corners of a room.

14. Understand the health risks associated with fine dust particles.

While you should never minimize the importance of hearing and eye protection, and the physical hazards associated with woodworking machinery and tools, it is the small dust particles which can be the greatest health threat. Exposure to fine wood dust has been linked to a variety of adverse health effects including: asthma, bronchitis.

15. Understand that the greatest respiratory health risks to woodworkers are the fine dust particles.

Dust particles are measured in micros – thousands of a millimeter. Particles greater than 100 micrometers are heavy enough and quickly fall to the floor. While removing these large dust particles will result in a cleaner and safer shop, it is the small particles less than 10 micrometers that pose the greatest respiratory health risks to woodworkers. These fine dust particles can become airborne and stay afloat in the air for minutes or even hours. They can also get into the deepest parts of your lungs and even into the bloodstream causing respiratory problems and other severe and chronic ailments.

16. Realize dust filters improve with use.

The fine-particle filtering ability of any type of dust filter (disposable mask, reusable respirator, central collection system, or shop vacuum) improves as the filter fills up with dust. As a filter fills up with dust it becomes more and more difficult for the fine particles to pass through. This may help explain why most filters state their efficiency – “after an initial break-in period.” So contrary to what you might think, you might not want to replace your respiratory – just because you have used it heavily. Instead, replace your respirator once breathing becomes slightly difficult.

Tips 17, 18 and 19 are for woodturners.

17. Realize most woodturners spend more time sanding than they spend turning.

This is why dust management is so important. With this statistic in mind, some turners feel the “American Association of Woodturners” should be changed to “American Association of Wood Sanders”.

18. Know why dust collection on a lathe can be difficult.

First, lathes do not have a dust port. This is unlike bandsaws and table saws where a dust port can be used to whisk away virtually all dust. Second, the direction the lathe is rotating (forward or reverse) can have a huge impact on where the dust goes. Third, the source of dust (i.e., the location of the sandpaper) varies with both the size of the turning and whether you are sanding the inside or outside of a piece.

19. Realize that dust collection in general is easier when sanding the outside of a piece.

In this case, a dust hood can be positioned fairly close to the turning capturing most of the dust. However, when sanding the inside of a piece, it is very difficult to get both the sand paper inside the piece and position a vacuum or dust hood close to the work.

Dust collection systems include: Powermatic, Jet, Laguna, Delta, Oneida, Grizzly, Harbor Freight,
Penn State Industries, DeWalt, Dust Deputy.

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Bill and Jodie Rosener | (918) 456-4482 | Tahlequah, OK 74464
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One thought on “Dust Control Tips (Duct work, Vacuums, AFD, & Collection Systems)

  • August 8, 2018 at
    Permalink

    I appreciate that the health risks associated with fine dust particles were discussed. Personally, I had never considered the dangers of something as small as a fine dust particle. After reading through this I’ve become aware of the importance of properly filtering the air and containing the dust particles when working with wood.

    Reply

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