The National Fire Prevention Association’s NFPA 61 standard for preventing fires and dust explosions in agricultural and food processing facilities went through some revisions.
NFPA 61 provides guidance on combustion risks in facilities handling, processing, or storing bulk agricultural materials, their by-products, or other agricultural-related dusts and materials. Although NFPA standards are not federal law, they become legally binding in local and state municipalities that have adopted them as regulatory code. In addition, OSHA can reference NFPA standards when levying fines for unsafe work environments under the General Duty clause.
Now, NFPA 61 better aligns with NFPA 652, “Standard on the Fundamentals of Combustible Dust,” to offer clarification on how to determine whether materials present in a process are combustible or explosible. This is an important responsibility for the owner or process operator and needs to be the first step in a combustible dust risk mitigation plan
The standard also introduces guidance on conducting a Dust Hazard Analysis (DHA). If you have a potentially combustible or explosible material in your facility, a DHA is developed to identify and address the risks present. NFPA 61 describes the methodology for a DHA and gives an example checklist. For any new process or existing processes being significantly changed, a DHA must be completed as part of the project.
The standard also contains a new section on the methods and requirements for the Performance-Based Design option for combustible dust risk mitigation. This option gives the process owner the flexibility to use alternative solutions based on good engineering principles and documentation in addition to the prescriptive requirements outlined in NFPA 61.
Process Review
Food processing facilities have been a leader in addressing combustible dust risks, but now some of those early systems are aging or out of date, and new technologies are available to upgrade them. At the same time, the Food Safety Modernization Act (FSMA) and increased production rates may be driving facilities to make changes in their food manufacturing processes. For this reason, it likely makes sense to combine the process equipment review with dust collection system evaluations if you are considering replacing aging dust collection systems. This review approach can help you address combustible dust risks, while highlighting a strategy that may integrate better with your production process and provide an optimized system.
Risk Mitigation Options
The process owner responsible for a DHA and combustible dust mitigation strategy should consider different options for effective risk mitigation. These include:
Facility Housekeeping
Some facilities with devastating events looked fastidious on the surface, but ignored dust accumulations on suspended ceilings, light fixtures, or girders. If an initial explosion disturbs this dust, it becomes suspended fuel for a secondary, building-wide deflagration. Make sure you inspect and periodically clean all surfaces from floor to ceiling, including walls, avoiding accumulations.
Dust Containment
Furthermore, removing dust from the air prevents it from accumulating on surfaces. An effectively designed dust collection system uses hoods to capture dust and the airflow transports it via duct to a dust collector. Food manufacturers in particular may have valid reasons for preferring indoor installations — and with today’s engineering advances that is more viable. Once the airflow requirements are known, then a dust collector can be chosen for the application and outdoor or indoor location reviewed, based on the equipment and strategy that works best for your facility and needs.
Mitigation Equipment
Both prevention and protection equipment options should be reviewed and considered for your mitigation strategy. A variety of equipment options are now available, including 1) active and passive isolation devices 2) explosion venting options and 3) fire or explosion suppression systems.
Independent combustible dust mitigation consultants can help you conduct a dust and process hazard analysis, and then recommend a strategy for your facility in accordance with NFPA’s standards.
To learn more about tackling combustible dusk risks, check out the complete version of this article published in Food Manufacturing online.
