If not handled safely and properly, the handling of wood dust can lead to disastrous and unintended consequences. Manufacturers have to be concerned about the associated health hazards for workers and the very real risk of combustible explosions.
Preventing these sorts of consequences from happening starts with how you handle the wood dust itself. Handling it in a safe and proper way can be thought of as a three-step process:
1. Capture It
The first step towards handling wood dust safely is to capture it at the source.
This is accomplished by the means of designing a good hood at each source of dust. Each machine has specific requirements in terms of the amount of suction, typically given as a combination of drop diameter and air velocity that must be maintained. Maintaining these air velocities while the machine is producing dust is absolutely critical.
Note that not all woodworking machine manufacturers thoroughly test their hood designs, and as a result, not all dust is collected even at the recommended air velocity in some machines. In these instances, it may be necessary to redesign and adjust the machine hoods.
How do you know if you should adjust your machine hood? If the machine manufacturer's specifications are being met at the hood and dust is still not captured reliably, changes are necessary.
2. Move It
Once the dust is captured at the source, it must be reliably transported to the dust collector. The air velocities required to reliably transport the contaminant vary depending on the contaminant type.
The American Conference of Governmental Industrial Hygienists provides recommended design velocities for different types of contaminants:
Depending on the specifics of the materials and processes used in each facility, the minimum transport velocity can be from 2000 feet per minute up to 4000 feet per minute.
One key element of maintaining transport velocities in the ducting is the design of the ducting system. In general, a good duct design should have the following characteristics:
Be as simple as possible and as short as possible, in order to minimize pressure losses
Suitable hoods for all machines
Minimize the number of elbows
Elbows no greater than 45 degrees
Flexible ducts should be avoided or used as minimally as possible
3. Deal With It
Finally, you need the right fan, motor, and dust collector. Factors that influence which fan, motor, and dust collector are right for your application would include:
Total air volume requirements
Type of dust
Production processes used
The fan should always be installed without system error - meaning the first elbow at the fan inlet should be at least 3 times the diameter away from the fan inlet (and ideally 5 times away). This significantly improves fan efficiency. A stack should be used on the fan outlet.
A direct-driven fan motor should be used; this provides better energy efficiency. Optionally, wood dust can later be recycled into new material (such as MDF board) or used to generate energy as a biofuel. Another use for sawdust is turning it into pellets, such as how Gildale Farms does.
Ultimately, each situation is unique and should be prepared for each individual project together with a domain expert.
A good dust collection system will provide a reliably clean and safe working environment that is conducive to high productivity.
Well-maintained industrial dust collection systems should have a life cycle of 20 years. It is critical to consider this when deciding what dust collection solution to deploy - money spent today on a superior solution can be recouped many times over the system's life cycle.
Author, Krystof Litomisky