Safety Insight: Dust Hazard Analysis (DHA) Fundamentals
Safety Insight: Dust Hazard Analysis (DHA) Fundamentals
Why should we be concerned?
Combustible dust fires and explosions continue to occur in the manufacturing industry. These incidents range in scale from small dust collector fires with no impact to personnel to large explosions involving multiple fatalities that cause significant supply chain disruption. There are many reputable consensus standards, guidance documents and studies published to help the manufacturing industry understand combustible dust hazards and take the necessary steps to prevent or mitigate these incidents.
If your manufacturing process involves powder handling or particulate solids, it is important for you to consider the following:
1. Can the material be lofted or suspended to form a cloud?
2. How does the material behave in different storage and processing environments?
3. Does the material ignite when exposed to moisture?
4. Does the material rapidly ignite when dispersed in the air and when contacted by an ignition source?
The best way to determine whether a dust fire or explosion hazard exists in your process, and to what extent, is to conduct a Dust Hazard Analysis (DHA). It is a fundamental work product that necessary for a strong combustible dust hazard risk mitigation program.
What is a DHA?
According to the 2019 edition of NFPA 652, “Standard on the Fundamentals of Combustible Dust,” a DHA is “a systematic review to identify and evaluate the potential fire, flash fire, or explosion hazards associated with the presence of one or more combustible particulate solids in a process or facility.” It is an evaluation conducted by a team with the right knowledge, experience, and information to predict what might happen during routine and upset operations.
A DHA requires multi-disciplinary commitment from your facility and may include input from engineering, operators, maintenance workers, health & safety personnel, and many others. Here is a basic workflow to consider when performing a DHA:
1. Assemble the right team. The team should be made up of associates from a wide range of responsibilities and disciplines in your facility and have adequate knowledge, skills, and experience to predict what might happen (and how bad it could be) under normal and upset processing conditions.
2. Gather as much information on the particulate solids you handle or process. Information includes but is not limited to:
- Safety Data Sheets
- Particle size distribution
- Flammability data
3. Gather process and equipment information including the following:
- Process flow diagrams
- Original Equipment Manufacture Specifications
- Fire protection and other safety systems specifications
4. As a team, review each phase of the process and the associated equipment involved. For each part of the process, consider the following:
- Where do potential hazards exist?
- Where hazards exist, how are they being managed?
- Is the management of hazards effective?
- Are there hazards not being managed?
- If mitigation doesn’t exist or is lacking, what corrective actions need to be taken to improve or address the concerns?
5. Document all observations, findings, recommendations and corrective actions for the life of the process.
Where can you get more information?
Many local jurisdictions require facilities to conduct a DHA by September 7, 2020 because of a revision to the International Fire Code (IFC) which now requires compliance with NFPA 652. OSHA has publications available regarding combustible dust hazards and continues to inspect facilities via the Combustible Dust National Emphasis Program. For more information on dust testing, consulting services, and training on combustible dust hazards & conducting a DHA,
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