In today’s episode of the Dust Safety Science podcast, Stephen Watkins, application engineering manager at Nilfisk, outlines the features and benefits of appliances for combustible dust ACD and compares them to ClassII Division II vacuum systems.
What Is an ACD and Why Should It Matter?
Stephen explained that appliances for Combustible Dust (ACD) have emerged as a vital solution in managing combustible dust in non-hazardous environments. Before the advent of ACD certification, there was no standardized approach for dust collection in these settings. While electrical appliances are typically certified for safety, the absence of combustible dust certifications in the past left end users exposed to significant risks.
Combustible dust incidents involve three main elements: fuel, oxygen, and an ignition source. In most cases, the fuel and oxygen are unavoidable. Controlling ignition sources, such as static buildup or sparks from electronics, is the only way to mitigate these risks effectively. When combustible dust becomes airborne and confined within a vacuum system, the potential for a catastrophic event increases.
The introduction of ACD certification places the responsibility of ensuring equipment safety on manufacturers, allowing users to select marked machines with confidence. Without certification, users must rely on marketing materials and assume liability if a machine fails to meet safety standards. By contrast, certified equipment provides peace of mind and removes ambiguity from the decision-making process.
How Did ACD Certification Develop?
The certification process for ACD systems originated with the International Electrotechnical Commission (IEC). Historically, IEC standards were not widely adopted in North America for combustible dust collection. The 2016 version of IEC’s standard, 60335 Annex CC, addressed combustible dust but focused exclusively on Zone 22 environments, which were primarily relevant to Europe. This left a gap for non-hazardous environments.
In 2021, the IEC revised its standard with three key objectives:
- Expand its focus from Zone 22 to include all instances of combustible dust collection.
- Introduce the first electrical certification for combustible dust collection in non-hazardous environments.
- Make the standard globally adaptable.
This updated standard was harmonized with UL codes in North America by 2022, allowing ACD-certified equipment to gain official recognition. These advancements now provide an internationally consistent framework for manufacturers and users.
Where Are ACD and Class II, Division 2 Systems Used?
ACD systems are designed for non-classified areas where combustible dust does not pose a major external hazard. However, within the vacuum, the collected material creates an internally classified environment. ACD equipment focuses on safety within the vacuum’s internal components.
Class II, Division 2 (C2D2) systems, on the other hand, are suitable for areas where there is a chance of airborne combustible dust creating a hazardous environment. For example, if bulk materials spill and generate a dust plume, the surrounding area would be classified as C2D2. C2D1 systems, used in environments where combustible dust is consistently present, require even higher levels of protection.
What Are the Technical Differences Between ACD and C2D2 Systems?
Stephen emphasized that the primary difference lies in the scope of protection:
- ACD Systems: These systems focus on internal safety measures, including grounding, bonding, and the use of anti-static components from the hose inlet to the filter chamber. ACD systems also require certified filters to prevent harmful dust dispersion during operation.
- C2D2 Systems: C2D2 systems provide additional protections for external components. These systems must use anti-static casters, C2D2-rated plugs, and robust outer housing to prevent external dust ingress. Cooling air paths and material construction must also meet stringent anti-static and dust-proofing requirements.
For environments requiring heightened safety, such as C2D1 areas, equipment undergoes even more rigorous testing and must use specialized components like explosion-proof motors.
C2D2 systems address both internal and external hazards, ensuring that all potential ignition risks are mitigated. This level of protection is vital in facilities where the accidental dispersion of dust can create temporary hazardous environments.
How Should Companies Decide Between ACD and C2D2 Systems?
Stephen emphasized that companies must evaluate several factors when choosing between ACD and C2D2 systems. A step-by-step checklist can guide decision-making:
- Is Your Dust Combustible? Conduct dust testing to determine combustibility. Assume dust is combustible unless proven otherwise.
- Does Your Dust Include Combustible Metals? If yes, additional considerations and safety measures will apply.
- What Is the Risk of Dust-Laden Air Near the Vacuum?This assessment determines whether a C2D2 system is necessary.
- Where Will the Equipment Be Operated? Consider whether the vacuum will be used near processes that could release combustible dust into the air.
Decision-makers should consult with dust hazard analysis (DHA) professionals or the designated authority in their organization. This authority, whether a fire marshal, insurance provider, or internal manager, holds responsibility for ensuring compliance. Proper assessment ensures the chosen system meets both safety requirements and operational needs.
What Are the Certification Requirements for ACD and C2D2 Systems?
These systems have different certification processes:
- ACD Certification: While third-party certification is not mandatory, manufacturers must meet stringent safety criteria. Self-certification involves thorough testing but carries inherent bias risks. Third-party certification eliminates this bias, offering users greater confidence.
- C2D2 Certification: Third-party certification is mandatory, ensuring consistent adherence to safety standards. The process involves rigorous testing of both internal and external components.
Both systems undergo similar internal testing, as ACD standards borrow elements from C2D2 protocols. However, external component testing for C2D2 equipment includes additional requirements, such as anti-static materials and dust ingress protection.
Why Is ACD Certification Important Even Without OSHA Recognition?
Although ACD certification is not yet recognized by OSHA, it still provides an extra layer of assurance. Certified equipment demonstrates that manufacturers have taken steps to ensure safety, reducing liability for end users. This proactive approach can prevent accidents and regulatory challenges, supporting safer operations overall.
ACD certification also offers a pathway for industries to adopt better safety practices before regulations mandate compliance. Proactively using certified equipment can also improve relationships with insurers, as it demonstrates a commitment to safety.
The Importance of Education and Training
Operators must understand the differences between these systems and their applications. Training programs can help staff identify potential hazards and ensure proper equipment use. Organizations should invest in educating their teams about combustible dust risks, proper maintenance, and equipment certification requirements.
Regular inspections and maintenance routines further support safety. Certified equipment remains effective only if it is properly maintained. Periodic reviews of operational practices can identify areas for improvement and reinforce safe working conditions.
Conclusion
ACD and C2D2 systems play distinct roles in managing combustible dust risks. Understanding the technical differences, certification processes, and appropriate applications for each system is critical. Companies should work closely with authorities, conduct thorough risk assessments, and choose certified equipment to ensure safety and compliance. By adopting ACD certification and best practices, organizations can mitigate hazards and operate with greater confidence in their dust management strategies.
Incorporating certified systems into your operations is not just about compliance; it’s about fostering a culture of safety. As industries evolve, staying ahead with proactive measures ensures the well-being of employees and the integrity of facilities.
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Stephen Watkins directly:
Website: https://www.nilfisk.com/global/
LinkedIn: https://www.linkedin.com/in/swatkins818/
Email: [email protected]
If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.
Resources mentioned
The resources mentioned in this episode are listed below.
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Companies
Nilfisk
Organizations
International Electrotechnical Commission (IEC)
