Government agencies in the United States have played a significant part in the dissemination of dust collection equipment. “In terms of air quality, OSHA wants clean air inside for the employees, and EPA wants clean air outside for the public,” says Patrick Ostrenga, a retired 34-year veteran of OSHA and founder of Occupational Safety and Health Auditing, Compliance Assistance Services (www.oshacas.com). An important safety issue driving dust collection is the danger of fire and explosion from some kinds of dust.
“I’ve studied several dust explosions due to combustible dust,” says Ostrenga. “Cornstarch was one that blew in a candy plant. Until the demolition of the old Schlitz/Pillsbury elevator in the late 1990s, none of the old grain elevators were demolished; they all burned. Unfortunately, the fires occurred while they were still operating.”
Fire isn’t the only issue driving dust collection. “I personally have a dust collection system in my basement for my saws, sanders, and woodworking equipment,” says Ostrenga. “Many woods are irritants, and some are suspect carcinogens. Treated lumber at one time had CCA, an arsenic compound.”
“To provide optimum safety, the dust collection system for a particular plant must take into account a lot of the characteristics of the production system it serves,” says Bill Thumme, president of Environmental Solutions (www.dustcollectionpros.com), which sells equipment from Donaldson Torit. “To direct explosions up, there are membranes that tear to protect the plant and equipment. Isolation valves can be installed at the collector inlet and air locks at the dump end to help prevent fires from moving beyond the collector. The inlet structure is typically built of thicker steel than the collector for fire prevention in the plant. The rules are not yet settled for some flammability issues. Also, each factory makes unique demands on the system. That is why a wide variety of options are available.”
For spark-generating applications, a range of features and technologies are available, from flame-retardant filter media to spark arrestors and fire sprinkler systems, explains Tomm Frungillo, vice president of Camfil Farr Air Pollution Control (www.camfilfarr.com). If a dust is considered even slightly explosive, the collector will have to be equipped with an explosion venting or suppression system. In these instances, dust collector vessel strength is an important factor in sizing the explosion protection system. A heavy-duty collector, constructed of thicker gauge metal and with a higher pressure rating, will stand up better in the event of a combustible-dust explosion and may enable you to use a simpler and less costly explosion protection system to comply with NFPA standards.
With so many choices, how do you know which type and level of protection is needed? Have your dust tested by an independent lab specializing in combustible dust testing. From there, you can work with your dust collection supplier to analyze your needs and determine the best solution.
Linn Vehslage is the maintenance manager of a factory that produces grinding wheels in South Beloit, Illinois. Not surprisingly, that plant, the Garden Abrasives factory, a Cinetic Landis company (www.fivesgroup.com/tools), produces a great deal of dust. The dust in Vehslage’s plant is very abrasive, being mostly grinding media and binders. Fortunately, it isn’t terribly flammable, but Vehslage is a believer in modern dust collection. “If you work with the systems and understand them, they can save you a lot of money and a lot of problems in the plant,” he says. “They can cut down on the need for masks and other PPE in large areas of the plant. They can also reduce contamination and wear on electric motors, blowers, and other equipment.”
A dust collector can contribute enormously to safety in plants today by ensuring that the air is safe to breathe, by reducing fire and explosion hazards, by improving visibility in the workplace, and by preventing slips and falls caused by dust buildup, says Frungillo. “Conversely, a dust collector that is not properly designed or is wrong for the application can detract from achieving these goals,” he says. “If a dust collector delivers clean indoor air to workers to limit their exposure to hazardous dusts and reduce allergy exposure, is that a safety benefit or an environmental one? It’s both, and it’s often difficult to separate these two issues.”