If you are working in food and agricultural processing, you know combustible dust control is a big part of your risk mitigation strategy.
But with the new edition of the National Fire Protection Association (NFPA) standards on combustible dust, representing industry best practices, it’s important to stay on top of these changes. Especially since OSHA inspectors are known to reference them under the General Duty clause and numerous cities have adopted them into code.
Have you considered when the last time was that you reviewed and revised your combustible dust mitigation plan?
For food and agricultural processing, NFPA 61, Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities is the most relevant.
The new edition of the standard states any existing food or agricultural processing facility with combustible or explodable dust needs to complete a dust hazard analysis (DHA) before January 01, 2022.
The new standard includes a chapter identifying hazards, including a sample DHA process checklist. After you have identified your risks, look at the strategies and equipment you need to mitigate those risks.
These top five options will help you prevent combustion, lowering risk, and protecting your facility during the initial stages of fire or explosion.
To start, good housekeeping of your facility is the basis of any risk mitigation process and is fundamental to preventing serious fires and explosions. Initial fires or explosions disturb dust that may have built up on walls, pipes, ceilings, girders, and other surfaces, which can then cause a larger secondary explosion.
Take the time to regularly inspect your facility from floor to ceiling, checking carefully for any dust buildup that may have been missed. Check-in with your cleaning crew regularly to make sure that they’re staying on top of any issues.
The simplest way to reduce the amount of dust you have in the air or on surfaces is by collecting it. New advancements in dust collection technology give you a wide range of options to create airflow that captures dust at specific points and then moves it into a dust collector for safe disposal.
This technology can include a range of indoor point-of-use dust collectors that removes it close to its generation point. This leads to a cleaner facility, limits on cross-contamination between product lines or volatile substances, and reduced downtime, where a single collector can be turned off without impacting your entire production line.
Isolation devices sense increases in pressure at the very first stages of combustion events. They close off access to the area, isolating the deflagration from continuing to move through your ductwork. These can include passive devices, which are flow-actuated isolation valves that activate when a pressure wave moves them.
Also, active devices use sensors to detect flame, pressure, and smoke. Then it uses signals to initiate a series of predetermined responses, such as activating explosion isolation valves or fire abort dampers to move smoke and fire away from other problem areas.
Explosion venting is carefully designed to intentionally burst open at specific pressure points so that gasses can be released at a specific safe location, mitigating explosive dust. It is a relatively effective control measure, but typically must be vented to the outdoors to work well, creating additional liability risk or extensive construction to isolate a safe area.
Flameless explosion vents use stainless steel vents to control the front of the flame while pressure is still being relieved, which does not require outside venting, but their performance is markedly different from traditional explosion vents, requiring professional advice to design an effective system for your facility.
Explosion Suppression Systems
This type of active system utilizes sensors to pick up pressure changes, which then causes it to inject chemical flame suppressants, typically sodium bicarbonate, into the dust collector. The entire process takes a fraction of a second. This can reduce your risk of having secondary fires or explosions occur.
They also may help reduce clean-up time following an incident. They provide a solid option for indoor environments or when the dust needs to stay within the collector. They can also be used at inlet and outlet ducts to isolate those systems from the rest of your combustible dust mitigation system.
Developing a DHA, including any significant change or new processing, takes careful thought, so consider any remodeling or expansion plans you are making. This includes changes to comply with the Food Safety Modernization Act, technological advancements, or increased production.
Consider the total cost of combustion events compared to the advanced technologies, and you will see an overall win for your company’s finances.