The Risks of Combustible Dust

Combustible dust is dangerous. Since 1995, fugitive dust has caused at least nine explosions across North America, which have destroyed facilities and injured or killed employees. The dangers of combustible dust came to center stage in the U.S, however, in February 2008, when a tragic dust explosion occurred in a Georgia sugar plant, killing 13 and seriously injuring 60.

After this tragedy, the U.S. Department of Labor Occupational Safety & Health Administration (OSHA) began a more rigorous initiative, called the National Emphasis Program (NEP), to make sure plants across all industries took the risks associated with combustible dust seriously.

The U.S. Congress required OSHA to enforce National Fire Prevention Association (NFPA) 654 Standards. These standards are the basis for OSHA’s housekeeping regulations and its Combustible Dust National Emphasis Program. Failure to comply can mean heavy fines; OSHA is vigorously pursuing this. In fact, OSHA is now required to look at combustible dust issues even if the inspection is precipitated by other concerns. (See OSHA Directive No. CPL 03-00-008.)

Recyclers must pay attention. Essentially, these changes mean that every plant is subject to this requirement and must be prepared.

Critical questions
Fundamental questions must be answered before practical solutions for dust management can be determined. The tree basic questions important for recyclers are:

1. What are the tolerance levels for combustible dust that best protect employees and assure compliance with regulations?
2. What is the smartest way to establish and then maintain continuous compliance at a plant?
3. What solution delivers the best return on investment and best manages low combustible dust levels in my plant?

Let’s take a closer look at the answers to each of these questions.

Stringent compliance levels required
According to NFPA 654, A-4-2.1, “Dust layers 1/32 inch (0.8 millimeters) thick can be sufficient to warrant immediate cleaning of the area.” (This is about the diameter of a paper clip wire or the thickness of the lead in a mechanical pencil.)

A-4-2.1 (b) continues, “The dust layer is capable of creating a hazardous condition if it exceeds 5 percent of the building floor area.” (If the floor area exceeds 20,000 square feet, a 1,000-square-foot [94-square meter] layer of dust is the upper limit.)

The practical reality is that these regulatory requirements mean that there is a zero-tolerance approach to dust buildup in plants.

Recyclers must find ways to deal with this. But what can they do?

Here are some options to consider.
 

Managed versus Engineered solutions
The OSHA directives can be addressed in different ways. Basically, there are two strategies: a managed solution or an engineered solution. In fact, the NFPA 654 standard refers to a managed solution, which has been the status quo.

Managed solutions often require human labor and periodic vacuuming. This approach offers:

• Relatively low upfront costs;
• Ongoing costs;
• Risk to cleaning personnel;
• Cyclical levels of cleanliness for the plant—sometimes the plant is dirtier than other times;
• Forced production shutdown; and
• An tendency to procrastinate.

The managed approach may be appealing because it is the status quo in many recycling plants. But the cost of maintaining the status quo is still ongoing and expensive. What’s more, with a managed solution, you don’t have a consistent level of compliance; it’s more of a roller coaster, where the plant is very clean and then is very dirty until the overhead cleaning is completed again.

In terms of engineered solutions, you have a two-part solution: localized filtration where practical, and the use of enterprise-wide clean-fan technology systems.

With localized filtration, a significant portion of the dust is captured with a suction action. With this approach, you still have issues with particles throughout the plant, as there is no way to capture every particle. To eliminate the dust that hasn’t been captured, an enterprise-wide clean fan technology system is required to meet OSHA regulations.

An enterprise-wide solution is a strategy that works throughout the entire facility. Using clean-fan technology, the system uses high velocity and robotically directed air flow. This can help establish and maintain cleanliness levels that OSHA requires. (The sidebar, above right, provides an example of how Cintas was able to find an enterprise-wide solution to the issue of combustible dust.)

An enterprise-wide engineered solution entails:

• Higher upfront costs;
• A one-time investment;
• Higher cleanliness, as all areas can be reached;
• Consistent cleanliness levels for ongoing compliance;
• Safe for employees;
• No interference with production; and
• Cleaning is automatically controlled.

Decision-making criteria
Regardless of the solution selected, the overall cost for any choice should be evaluated based on a range of variables, including:

• Initial cost of purchase;
• Operating costs;
• Ongoing labor costs;
• Effect on employee moral;
• Disruption of normal processing; and
• Return on investment.

Recyclers need to be diligent to find the best solution to keep their facilities continually in compliance with government regulations, avoid fines and protect their employees.

Brad Carr is president of IES (Integrated Environmental Solutions), which manufactures SonicAire fan systems. He is a professional engineer with more than 38 years’ experience in air handling systems and equipment. He can be contacted at 336-712-2437 or at bcarr@iesclean.com.