Health and Safety
Top 5 FAQs about a Dust Hazard Analysis
By Brian Edwards
By Brian Edwards
A Dust Hazard Analysis (DHA) is a comprehensive assessment of an industrial facility and its processes to identify areas where explosion and fire hazards may exist. Based on these findings, recommendations are notated and an action plan is executed to eliminate ignition sources and safely mitigate any possible explosions or fires.
This article is intended to answer some of the most common questions received by the consultancy team at Fike Corporation and those which may be valuable to the Canadian biomass industry.
1. Are Canadian facilities required to complete a DHA?
DHAs are required by several National Fire Protection Association (NFPA) standards. The National Fire Code of Canada, as well as most provincial fire codes, reference various NFPA standards for combustible dust. However, these references are typically not mandates, which means facilities may not be required to comply with specific sections of the NFPA standards.
That said, the purpose of a DHA is to identify hazards at a facility and help develop a strategy for minimizing risks. The focus of a DHA is the safety of your operations, regardless of the regulatory requirements. Therefore, DHAs are always highly recommended for facilities which handle combustible materials because it could ultimately save someone’s life.
2. What is the difference between dust combustibility testing and a DHA?
Dust combustibility testing is commonly mistaken for a DHA. Dust testing consists of laboratory analyses of the dust to determine if the material will burn in air, and, if so, how energetic is a flash-fire, how sensitive is the dust to ignition, what is the minimum concentration of dust needed for an explosion, etc.
Dust testing is used to determine the hazards and properties of the material, but it does not look at the process. A full DHA looks at the processes, equipment, and occupancies where the dust is handled or generated. A dust test does not satisfy the need for a full DHA, unless the dust is found to be non-combustible.
3. Do I need to test my wood dust as part of the DHA?
Decades of empirical data on the combustibility of wood dust is available in several resources. Some variability exists between various species of wood, but the most important factors that affect the combustibility of wood dust are moisture content and particle size.
If you know those two values at various stages of the process, an experienced professional should be able to complete your DHA. However, there may be times where testing may be useful, such as determining if a specific conveying stream presents a deflagration hazard. Your DHA professional will be able to advise when dust testing can be useful.
4. For new projects, when in the design phase should a DHA be completed?
A DHA should be completed as early in the design process as possible. Once a conceptual process flow and/or general arrangement of equipment has been established, a preliminary DHA can be performed.
The DHA should be used to determine where fire and explosion protection systems are required, so it is important that this is determined prior to finalizing specific equipment selections. Determining whether explosion protection is required for a piece of equipment after a purchase order has been issued will certainly delay a project.
5. Can I perform my own DHA or is an outside expert required?
A DHA will be led by a “qualified person,” as defined by NFPA 652 3.3.39: “a person who, by possession of a recognized degree, certificate, professional standing, or skill, and who, by knowledge, training and experience, has demonstrated the ability to deal with problems related to the subject matter, the work, or the project.”
It is possible for a qualified person to be employed by the facility and serve as the DHA lead. Even so, the DHA lead will also require the assistance of the facility’s subject matter experts: engineers, operations managers, maintenance managers, and more. Each of these experts can provide insight to specific areas of the DHA. For example, a maintenance manager can describe the preventative maintenance programs and various failure modes that could be potential ignition sources.
Most facilities have the experts to contribute to the DHA but usually don’t have the qualified person to serve as the DHA lead. In these common scenarios, the assistance of an outside combustible dust safety expert is required to ensure the DHA is performed accurately, potential hazards are reliably identified, and a usable action plan is developed from the findings.
Brian Edwards has a degree in civil and environmental engineering from Georgia Tech, and he is a licensed Professional Engineer with over 20 years of experience as a consultant to industry. Brian is the explosion protection consultancy manager at Fike, where he uses his decades of experience managing combustible dust hazards to assist their customers. He is a member of the NFPA, and has previously sat the committees for NFPA 61 and 664.