W&WP June 1999
The Keys To Effective Dust Collection
Experts agree that reviewing both current requirements and future growth are paramount to designing and maintaining an efficient dust collection system.
By John Iwanski
Wood products companies are facing increasing pressure, not just from employees or the Occupational Safety and Health Administration, but from themselves to promote a healthy work environment. A decreased labor pool means employers more than ever want to keep their employees healthy and in top shape.
OSHA currently requires shops that produce wood dust to meet a dust exposure requirement of 15 milligrams per cubic meter of space. This limit was originally established in 1971 and was brought back in 1992 when a federal court ruled that the 5mg/cm limit OSHA implemented in 1989 was not reached under proper rulemaking practices.
However, even with all the concerns and changes in regulations, companies are looking for answers. Many shops are looking at new ways of minimizing wood dust emissions while attempting to maintain profitability.
With this in mind, Wood & Wood Products spoke with some experts in the dust collection industry to find out what the most common problem is that they see in the field every day. They also spoke about some unique situations that have required unusual solutions, as well as discussed what wood product manufacturers should look for before they purchase or upgrade a collection system.
Here are some of the things the dust collection industry experts had to say, covering everything from ductwork and collection units, to planning a system and purchasing the right collector for now and the future.
Plan Before You Buy
"A common problem I have is that people will come to me and say 'I've purchased a 5-hp dust collector and I need you to design the system.' Then, after I go in and figure out the requirements, I have to tell the customer that they need a 7 1/2-hp or 10-hp unit. They usually aren't real happy at that point."
Riccardo Azzoni, president of New Milford, CT-based Atlantic Machinery Corp. agrees, saying, "Dust collection systems should be purchased by taking into consideration the efficiency of units and the filtration capacity.
"Just putting a large motor on a dust system does not improve efficiency unless you have an adequate air exchange," adds Azzoni. "The unwillingness of the customer to spend money on the right dust collection system is the most common obstacle I see in the industry."
According to Robert Witter, owner of Syracuse, NY-based Oneida Air Systems Inc., many small shop owners simply are not prepared for what some companies throw at them in terms of dust collection technology.
"There's a lot of misconception about dust collection, especially on the small shop level," says Witter. "What we find quite often in small shops is makeshift-type collection equipment. That usually is self-defeating because the air that is supposed to be cleaned is going right through the filter bags and exacerbating the problem.
"Then, if they get a large quote from a company who can't really work with the smaller-scale problems that their shop incurs, they continue to look at 'stop-gap' methods that don't help themselves or their products. I've seen shops pushing 10mg/1 cubic meter through their filter bags. All you have then is blow through. You know it and the customer knows it."
Resolving Problems Before They Occur
"Eighty to ninety percent of the time, people buy a dust collector that isn't going to do what they want it to," says Corum. "We (dust collection suppliers) have to educate people to use the right product and engineer it properly. Companies need to do their homework to be sure that they have the proper collection and filter device that will provide the proper vacuum and filtration."
Chuck Morrison, product manager for Thomasville, NC-based DISA, says that knowing the company and what it can deliver is key in the evolving world of industrial air filtration and dust collection.
"Is the customer working with a reputable manufacturer, contractor or representative?" says Morrison. "That is very important. Also, the design of a system is important, from the ducting drops through the fan design, as well as the collector design and removal plan."
All these factors must be taken into account before the wood product manufacturer invests a large portion of capital into dust collection, says Morrison.
"Customers generally end up looking for the cheapest alternative rather than the best value for their investment," continues Morrison. "That usually isn't the best thing to do."
Dust Collection as an Investment
"Improved collection means improved employee morale due to cleanliness. It also improves tooling life due to cleanliness and reduced wear on the tool as well as improved product quality output," says Morrison. "These are important factors which are often overlooked."
According to Witter, customers are slowly but surely beginning to recognize the value of an effective dust evacuation system.
"Customers are beginning to see that central dust collection works. Clients will say, 'I can't imagine that I ever operated before without this.' In a lot of ways, it's like a microwave oven. The quality of air improves so much, clients don't know how their shops functioned before we put in a system."
Planning for the Future
"Shop and company owners have to take into account expansion or they will find themselves in the same situation they were in before they added their system," Kraemer continues. "Customers don't consider add-ons when they plan and that can really hurt the viability of the system that's been installed."
Another important factor to consider is the transport velocity that occurs in the ductwork. According to Faith Salchert of Donaldson/Torit Products, that velocity can be reduced if customers don't take into consideration the possibility of future expansion.
"It's really important to have adequate transfer and transport velocity," says Salchert. "If they add a new piece of equipment, there needs to be a little bit of design consideration built into the system for what they are doing. You can't simply pipe it into the main ductwork and expect the system to operate at an optimum level.
"The collection system will be able to move a certain amount of dust, clean the air and recirculate it into the shop," continues Salchert. "But when companies just start throwing machines onto the system and don't allow for upgrades in other areas, they will be in for trouble over the long run."
Designing a System That Fits the Shop's Needs and Budget
Most experts agree that knowing how much dust one's shop produces is the most important factor involved in dust collection system design. If manufacturers do not know how much wood dust is being produced, it is a safe bet that they have no idea what type of collector or removal system is needed either.
"A lot of shops, when you ask them about how much actual dust they will put out in an hour or an eight hour workday, they don't have any idea," says Neil Rosenquest, president of Addison, IL-based Dustvent. "So how can a shop owner make a educated decision about collection when it's not clear how much dust is being created in the first place?
"Some shops might only need a 55-gallon drum and a chip collector for what they generate," continues Rosenquest. "But when you start getting into machines like moulders, you can fill a 55-gallon barrel in 20 minutes. You have to know what you're putting out in order to develop a system that will not only improve the health of your workers, but also provide safety in your shop."
Andrew Wichlinski of Alsip, IL-based Scientific Dust Collectors agrees that getting a customer to see the benefits of a good dust collection system is not always easy, especially when costing and budgeting is a big concern.
"The problem that is the same throughout the industry is convincing the small- to medium-sized shop that dust collection is important. That is so difficult sometimes," says Wichlinski. "Dust collection is important, but it doesn't show up directly in the bottom line in terms of increased profits or improved productivity.
"So what the industry is faced with is educating manufacturers that dust collection can be cost-effective and still benefit the shop. Keeping a clean shop and employees healthy is important, but when a smaller shop sees a $15,000 bill for dust collection, they don't exactly jump to sign on," continues Wichlinski. "What companies need to recognize is that they can improve their product quality as well as increase the life of their tooling by investing in a good collection system. We (dust collection suppliers) can put in place a collector and filtration system that will pay for itself in terms of improved finish quality and reduced employee leave and clean-up times. Not to mention the fact that it complies with safety ordinances and reduces the possibility of fires or explosions within the shop."
"It's potentially explosive," says Wichlinski. "Wood dust can catch fire at any time, and if you have it laying on the ground or, even worse, floating in the air, you have the potential for a flash fire situation."
According to Corum, there are a lot of different safeguards that can be put in place to prevent safety problems. But manufacturers should always be sure to use the product in the context of the proper application.
"Some collection units still have 20-30 micron tolerance. If you are letting that kind of air circulate in the shop, there is the potential for a hazardous situation," says Corum. "Adding other devices such as a ceiling-contained dust collection unit can help you maintain your limits. But if you are blowing that much dust out into the shop (20-30 microns), the ceiling unit isn't going to be able to handle that effectively. That isn't what it's designed for. All the pieces of the puzzle have to fit together to eliminate the problem and circulate clean air back inside the workplace."
Be Aware of Local Laws
Otto Siemen, president of Huntington Park, CA-based Murphy-Rodgers says that though OSHA's present federal wood dust standard is broad, many states and cities are enforcing laws that are even more stringent and that is what manufacturers must look out for.
"Satisfying local municipal authorities and local standards has become a greater problem than (the regulation) of OSHA," Siemen says.
Those sentiments were echoed by Witter, who noted that he is sometimes as confused about the regulations as some of his customers are. "You try to lower the dust to an acceptable level," says Witter. "But what is that? There are so many studies out there, that a lot of times the customer isn't sure what acceptable levels should be."
Peter Levitt of Bogota, NJ-based Sternvent, says he thinks that the ambiguity of the exposure limits has been a hindrance to the industry. As a result, more manufacturers in the wood products industry are faced with decisions to purchase a product that may or may not help their company improve their air quality and also be compliant with the most recent standards and requirements.
"When it comes to safety and compliance in dust collection, a lot of companies don't know where to go," says Levitt. "A lot of times, the fire codes in certain states or municipalities are more stringent than OSHA's regulations. So when a system is installed, the fabricator has to make sure that all of the requirements are met or the client will have a system online that doesn't take care of their needs and won't be up to code for the local fire department."
Filtration Developments Aid Manufacturers
"The key to minimizing dust in the shop is filtering it," says Witter. "There are a lot of filtering systems out there, and a lot of those still use filter bags. The bags do fine, as long as you use an improved media in the proper amount for the amount of dust that will move through that bag."
The improvement in fine filter media has had a large impact on how dust collection companies design filtration systems and the recommendations they make to their potential customers. The increased popularity of fine filter products has also allowed companies to significantly decrease the amount of fine dust in the air, potentially the most dangerous because of its "invisibility". "If companies have a lot of fine dust being generated, sanding with fine grit paper that takes off just a little bit of wood, then they have to do two things," says Kraemer. "They must account for more filter ratio, first and foremost. They need to have a wonderful filter ratio. If the customer doesn't have many small particles, but more large chips, that's fine. They can have a lower ratio of filter media. But fine dust needs more filter area to remove it, or the dust will simply recirculate back into the shop.
"They also need to be sure that the media they use is checked regularly. If the media is not checked, they may get to a point where they simply have the dust blowing through back into the work area," Kraemer continues. "That obviously is something that no one wants to have happen."
Fine dust is a problem that Salchert says is becoming increasingly concerning for manufacturers, even for smaller-sized woodworking operations.
"One of the unique trends that the industry is seeing is the move toward cartridge filtering and getting away from bag filtration," Salchert says. "I think that's more because companies want to get away from fine dust. They don't want dust all over their expensive machinery because it can affect overall production. The cartridge system also allows for easier maintenance than that of a bag, so they have that as a positive for looking at that type of filtration system as well."
Salchert also says that as cartridge media becomes more prevalent, companies will begin to see the benefits that the system offers. "Companies are always looking for ways to improve production and quality. Cartridge systems overall provide easier maintenance and really reduce the amount of dust that will circulate in the workshop."
Disposing the Collected Dust
"The storage, handling and disposal of collected wood dust, chips, etc., in a simple and economical manner is a major problem for most woodworking facilities," says Levitt. "The collection units vary from a 55-gallon drum or a series of plastic bags for small or non-production shops to a dust collector with a large storage hopper of 100 to 300 cubic feet on a truck stand."
However, larger stands are not necessarily better, says Levitt. The way the waste is disposed of is nearly as important as how it is collected.
"Two disadvantages of a large hopper are the tendency of material to bridge inside, slowing or stopping flow, and also the cloud of dust that's created," says Levitt. "Many times, a better alternative is a continuous discharge from the collector through a motorized rotary airlock into a dock cart or dumpster that includes a plastic liner which will contain the dust when it's dumped into a larger container."
According to Salchert, a common problem results when customers do not keep collection areas orderly. The units then begin to back-up, but customers don't understand why they have problems with overflow.
"Another area that manufacturers really need to look out for is their dust storage area," says Salchert. "That area must be maintained, or dust can fill it up into the collection system and collector, which impacts the performance of the unit. Many times people will have a problem and not even bother to check and see if the collector is full. If it is backing up into the collector or the ductwork, the manufacturer may have a potentially serious problem."
Two Dust Collection Case Studies
"One thing that you can say about dust collection is that nearly every situation is unique," says Corum. "The industry is approached with unique problems on a daily basis. Ducting is always an interesting aspect of collection because it has to allow for proper flow and velocity but not be too cumbersome."
Corum notes that on a recent Air Handling Systems project that involved ductwork for the television show New Yankee Workshop, the biggest challenge involved the noise of the collector.
"We had all the sound problems that go with a television production, as well as the aesthetics involved with viewing. We ended up modifying some of the hood fittings and adjusting the ductwork so that the projects could be completed without the noise of a typical shop," Corum says.
"We had to change the standard fitting on a chop saw and cut a tapered funnel tight underneath the machine. And by changing from an 8-inch to a 4-inch bottom, it keeps the air moving around it. You can't put a hood on that, especially with television showing what work is being done, so it enabled the machine to work with a conventional dust collection system and still allowed viewers to see the action."
Levitt says that one of the largest problems Sternvent has encountered was with a toy manufacturer who began producing pencils.
"The company used 'shop-vacs' to pick up the waste, but after a half hour, it was obvious they weren't going to work," says Levitt. "They didn't provide enough airflow nor enough storage capacity. The majority of wood waste, which was shavings, filled a 55-gallon drum in less than 15 minutes.
"A baghouse collector wouldn't work either because of the bulk and light density of the shavings," continues Levitt. "By using a high-efficiency cyclone with a top-mounted fan, the customer was assured that no shavings would bridge inside the cyclone because of the high velocity and down flow air pattern. Then a rotary air lock was attached to the cyclone with a surge receiver for a continuous discharge of shavings into an open top container."
Suppliers Advice: Be Prepared
"With the increased use of high- powered equipment, especially in smaller shops, collection is really important," says Witter. "Ten, twenty years ago, those shops used hand tools."
According to Wichlinski, collection manufacturers also work with companies and are prepared for almost anything.
"We have to configure each system differently," says Wichlinski. "There are so many ways to dispose of dust, it's important to be flexible and prepared, yet still provide an effective and safe way of eliminating waste. That's why clients are coming to us in the first place."
Determining How Much Dust Is Safe
Common sense tells us that limiting the amount of wood dust we breathe is a good idea. Indeed, the limitation of any outside particles from the human lung is generally accepted as good practice, whether in woodworking or medicine.
For most of the last three decades, putting a limit on wood dust emissions in the workplace has been hotly debated and contested. With the lack of substantiated studies and the difficulties associated with the cause and effect principles that accompany that type of research, the questions and debates have been ongoing.
In 1971, the Occupational Safety and Health Administration established a permissible exposure limit for wood dust. Classified as a "nuisance dust," wood dust had a limit of 15 milligrams per cubic meter of space.
In 1988, OSHA proposed that the standards be changed after reports that some wood dust may be carcinogenic. The new PEL limits were proposed at 5mg/cm for softwood and 1mg/cm for hardwoods. Industry leaders argued that the 1mg PEL would not be economically achievable and could not be substantiated by scientific evidence.
The following year, OSHA decided to implement a single PEL for all wood dust, established at 5mg/cm. This limit was based primarily on respiratory effects of wood dust exposure and was intended to be a benchmark for the industry. Certain hardwoods, such as western red cedar, had a PEL of 2.5mg/cm.
In 1992, several unions and industries challenged OSHA's PEL update rule and an appellate court overturned OSHA's air contaminants standard. The court said that OSHA had not followed correct and proper procedures in regards to rulemaking. As a result, the PEL standard reverted back to the old limit of 15 mg/cm.
Since then, numerous studies and inquiries have been conducted, with mixed results and conclusions. In 1994, the International Agency for Research on Cancer classified both hardwood and softwood dusts as human nasal carcinogens, with particular concern given to some species of hardwoods.
In 1996, the American Conference of Governmental Industrial Hygienists classified hardwood, but not softwood dust, as a human carcinogen. Two years later, the conference proposed a significant reduction in threshold limit values for wood dust, highlighting the respiratory effects that the inhalation of wood dust had on workers.
Many other studies of note have and are being conducted now. One significant study is being conducted at Tulane University and is sponsored by the Inter-Industry Wood Dust Coordinating Committee.The study, which will cost more than $2 million and is being funded by contributing members of the committee, plans to obtain scientific information as to what exposure levels, wood types and dust size fractions are important and harmful. By finding hard evidence, this study and others like it will be forwarded to OSHA as it looks at establishing new federal wood dust limits.
The study, which will be completed in the fall of 2004, will collect standardized annual measures of respiratory health. The measures will be collected by plant personnel certified to National Institute for Occupational Safety and Health standards to collect data. Tulane industrial hygienists will also conduct wood dust exposure tests on site at participating plants. The study will monitor 5,000 to 6,000 workers in 12 wood and wood products facilities.
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