Maintaining an efficient dust collection system is important for product quality and employee morale.

A dusty shop also is potentially hazardous to the employees who work in it. In December 2002, the National Toxicology Program added wood dust to its list of known human carcinogens.

"Dust particle removal has become more important, especially with the onset of a new government ruling classifying wood dust as a carcinogen," said Chuck Morrison, southeast regional manager of DISA Systems Inc., Clemmons, NC. "This makes the task of selecting a dust collection system even more difficult. The customer now needs knowledge or resources with knowledge about dust collection to understand areas such as filtering speed, air-to-media ratios, micron size, air volumes, velocities and National Fire Protection Assn. regulations."

Morrison is one of six industry experts interviewed by Wood & Wood Products. One of our goals was to learn of less-well-known tips for getting the best performance and longest life from a dust collection system.

Do You Have the Right Kind of System?

"Not all dust is created equal," explained Ricardo Azzoni of Atlantic Machinery, New Milford, CT, which distributes the Italian-made Coral dust cartridge systems. Azzoni said a shop that produces larger chips or coarser sawdust needs a system that focuses on efficiency, such as a containment silo, auxiliary blowers or an endless screw system to push the dust into a trailer, bin or truck. Plants that produce more fine dust, such as those working with more MDF or doing more finish sanding, need systems with a greater filtration area (called "air-to-cloth ratio") to prevent the filtering unit from clogging quickly.
Azzoni stressed that fine dust and coarse chips should not be mixed in the same duct.

"They travel at different speeds and the resulting friction can create a spark and lead to a fire in the ductwork. Separate lines for each kind of dust work better," he said.

Managers of plants that mainly produce fine dust should also consider the cartridge filter media they use. Filters made of paper or cellulose must be replaced regularly. Polyester filters have longer life spans, several of the experts said.

"Better filter media are being developed to produce a high particulate collection that meets government regulations," Morrison said. "Look for materials that do not produce high-pressure drops across the filter; they use less energy and have more efficient collection velocities."

Woodworkers also need to consider the pros and cons of internal versus external dust collection systems.

"Inside units conserve energy - loss of heat in winter, air conditioning in summer - but make dust disposal a messier affair," Azzoni says. "Outside units simplify this task, but you should consider a system that allows you to return the air into the building."

An improperly designed or installed dust collection system will not work effectively, allowing sawdust to pile up in corners or near machinery. This makes motors work harder, causing increased wear, shorter life and higher electricity consumption.

Mike Gerardi, general manager of Scientific Dust Collectors, Alsip, IL, strongly recommends installing blast gates at each pick-up port of every machine that produces dust. He also suggests that woodworking companies make sure their dust collectors provide the appropriate compressed air capacity and that the air system is properly sealed. "The cleaner and dryer the compressed air you're using, the longer the filter media will last and the better the system will work," Gerardi said.

"People don't always use the right ducting," said Curt Corum, sales manager of Air Handling Systems, Woodbridge, CT. "Dust collection ducting is not the same as heating and ventilation ducting - it doesn't have 90-degree junctions or short elbows, and it's not made of the same material." For a dust collection system to work properly, Corum said the ducts should have wider, more gradual bends. They must also be made of real blowpipe ducting material, which withstands abrasion while allowing air and particles to move through them at high speeds.

Regular Maintenance

"One of the beauties of a well-designed system is that the only thing you have to do is regular, routine maintenance to keep it operating at top performance for a long time," said Jeff Hill, general manager of Oneida Air Systems Inc., Syracuse, NY. He said as long as woodworkers regularly empty the drum, bag or bin, clean the filter, oil the motor and check the belts, the well-designed system should continue to cost-effectively collect dust for many years.

"With just simple, good housekeeping, a good system can last 20 or 30 years," said Rosemary Kraemer, head of Kraemer Tool & Mfg., Brampton, ON. She recommended regular oiling of the motor and checking of belts, shakers, valves, cleaners and other parts that can break down. Dust collection spark detectors also should be inspected regularly and the seals of systems with air locks should be examined for wear. "Remember, the air that comes back into the plant from the system is what you breathe," she added.

"Pay attention to the magnehelic gauge for pressure drop across the filter unit," Morrison said. "This will be an indication that a filter is getting plugged or needs attention. If there is not one supplied with the system, they can be purchased from most dust collector manufacturers. Once the filter becomes plugged or blinded, the results will be less airflow to the machines and waste of fan horsepower."

Seals at joints are also critical, Morrison continued. They can wear out, causing dust and air to leak out of the system. This situation taxes the motor more and draws more power.

In addition to oiling the motors, emptying the bins and cleaning the filters, woodworkers should watch out for dust collecting in odd places, poor pick-up or airflow and spills from collection bins. These are all signs that a system is not operating at optimal efficiency.

Have You Outgrown Your System?

If you have added equipment, shifts or an extension to your building, without upgrading your dust collection system, chances are your business has outgrown it. Often, a business will add branches or ducts from new machines to the existing system, which could overload it.

"Often, after a couple of years, a shop ends up with a cobbled-together dust removal system, rather than one designed for it," Hill said. Even daily wear-and-tear can lead to improvised solutions to repair malfunctions, such as the replacement of a dustbin with another part that was not designed for the system. While an improvised solution might seem to work, it is usually not as efficient. More likely than not, the dust collector will be less efficient and more costly in electricity requirements.

"It's a simple formula. If you get too much air volume going through too little filter area, you get dust," Kraemer said. "If you're expanding your building, you can't just add to the existing dust removal system - you need a whole new system."

Hill said that a large moulder or CNC router may require a collector of its own.

The reality is that most woodworking plants do not invest in a new dust collection system when they add a new machine. They just tie in to the one they have. This can work - to a point. Corum pointed out, however, that even when extending the ductwork, many shop owners or managers fail to install a proper hood over a new CNC machine or saw. Without the right hood, the dust collection system will not perform its function as well as it should.

Excess flex hose is another source of trouble, several experts said, adding that many shops use flex hose, rather than proper, solid dust ducts. This not only is another load on the motor, but also a potential source of failure. To achieve peak efficiency, only the minimum amount of flex hose should be used to remove dust from the hood or to accommodate the movement of the machine itself. Flex hose should not be used to extend the collection system to a new part of the shop.

New Technology Makes It Easier

Companies looking to install new dust collection systems or improve existing ones can take advantage of technological advances that make dust collection much more efficient and effective.

"A lot of R&D has gone into dust filter materials over the past few years," Corum said. Bean fabrics, felts and polyester offer alternatives to cotton filters. Corum added that these new media filter out more particles, last longer and allow better airflow.

Manufacturers of dust control systems offer more options in automation and monitoring, too. Sensors in drums, bins and other collection points can turn on indicator lights when they are full.

Reducing energy costs is a priority for many manufacturers, particularly larger shops. A dust collection system that automatically adjusts the speed of its motor according to the number of production machines running at any given moment can significantly reduce the amount of power that is consumed. Computer controls, electronic monitors and sensors, and variable-speed drives allow modern systems to do just that.

"The electricity saved is substantial," Morrison said. "A factory using this system could add more machinery with their existing dust collector or improve the performance of a dust collector that has been overwhelmed by a factory expansion."

Plan for the Future

The experts agreed that no wood shop manager should try to select a dust collection system alone, let alone install one. Instead, the smart manager should look for support and information from the experts.

"Many people ask for dust collection by motor horsepower, not really knowing whether it applies to their application or not," Azzoni said. "Dust collectors should be chosen based upon the application, which in turn dictates the cubic-foot-per-minute air volume requirements, static pressure and the motor's horsepower."

"You can no longer choose the basic boiler plate dust collector off the shelf and expect it to work for any application," Morrison said. "Dust collection has become a highly engineered science. To stay leaders, we will have to stay on top of these changes."

All of the experts agreed woodworking managers should keep the future in mind when installing or upgrading their dust collection systems.

"A system that can be upgraded and expanded in the field is a big plus," Azzoni said.

Morrison echoed Azzoni's comment. "Look for dust collectors that allow for growth of the system. This allows you to purchase the dust collection system presently required and expand the system as your needs and business grow."