How to Prevent Combustible Dust Explosions in Food Manufacturing Plants

How often do you think about the combustible dust at your food processing plant? Likely not often enough. Combustible dust is often underestimated as a hazard. This oversight can be disastrous. The destructive power of combustible dust makes ongoing, consistent attention and immediate corrective measures absolute musts. This article outlines a strategy you can use to prevent combustible dust explosions in your food plant based on National Fire Protection Association (NFPA) standards.

What is combustible dust?

OSHA defines combustible dust as any solid material that is composed of distinct particles and can present a fire hazard. In a food processing plant, that includes wheat flour, sugar, cornstarch, and other powders. You can find it in the air, in vents, or on any flat or hidden surface that isn’t cleaned regularly.

NFPA standards for food processing facilities

The NFPA issues several standards relating to combustible dust. For the food processing industry, there are two main standards you should be aware of:

• NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities. This standard provides guidance specific for the food industry.
• NFPA 652: Standards on the Fundamentals of Combustible Dust. This is a new standard that provides general requirements for managing combustible dust fires and explosions across all industries, processes, and dust types.

On their own, NFPA standards are not law. However, violating NFPA standards is a cite-able and fine-able offense under OSHA. Download our guide to NFPA standards for food processors.

What you can do to prevent combustible dust incidents at your food plant

Preventing combustible dust problems isn’t hard, but it does require awareness of the problem, facility-specific analysis of risks, and consistency in implementing housekeeping and other prevention procedures. Based on these NFPA standards, here are four measures you can take to prevent dust-related fires and explosions at your food processing plant.

1. Perform a dust hazard analysis

The first step in preventing a problem is understanding your risk. A combustible dust hazard analysis isn’t just a best practice. Under NFPA 652, it’s mandatory. Different dusts present different risks and can cause different levels of damage to your facility. NFPA 652 requires all facilities to test their dust so they’re fully aware of their risks. Your analysis will help you identify which materials and processing stages have the highest potential for a problem. Once you’ve identified and measured your risks, you can take appropriate methods to control them.

2. Keep ignition sources away from combustible material

The combination of combustible dust and an ignition source can be catastrophic. Most of the guidelines in both NFPA 61 and NFPA 652 focus on how to keep dust and sparks away from each other. You can achieve this through facility design and construction, dust collection, venting systems, and so on. Here are just a few examples of ways to avoid a catastrophe:

• Bond and ground your equipment to reduce static electricity. Certain food additive powders, like maltodextrin, are very sensitive to static. Make sure to ground your machinery and use antistatic equipment in areas where dust may be present.

• Implement a hot work program and obtain hot work permits when such work is required. In general, try to make sure hot work is performed in a designated area that is free of combustible dust. When this isn’t possible, ensure the area is properly cleaned before commencing work.

• Pay special attention to your heat transfer systems. High heat equals high risk. NFPA 61 requires heat transfer devices to be fitted with pressure relief valves, heaters and pumps for combustible heat transfer fluids to be located in separate dust-free rooms, and heat exchanges to be arranged in such a way that combustible dust can’t accumulate.

3. Implement and document proper housekeeping procedures

The more combustible dust that is in your plant, the greater your risk. NFPA 652 requires you to implement cleaning methods based on the type of dust present in your facility, with the goal of reducing the potential to create a combustible dust cloud. Here are the top three weapons in your combustible dust cleaning arsenal, in order of preference:

• Vacuuming. NFPA standards have different requirements for vacuums in areas classified as hazardous and non-hazardous. Make sure your vacuum system is approved for dust collection in food processing facilities.

• Sweeping/water washdown. These methods are permitted in areas where vacuuming is impractical.

• Blowdown. Blowdown is only permitted when vacuuming and sweeping/water washdown have already been used.

NFPA 652 also requires you to document all housekeeping procedures, specifically addressing these seven areas:

• Risk assessment with the specific characteristics of the dust
• Personal safety procedures
• Personal protective equipment
• Cleaning sequence
• Cleaning methods to be used
• Equipment including lifts, vacuum systems and attachments
• Cleaning frequency

4. Train your staff

Finally, NFPA 652 requires ongoing employee training on the potential exposure to combustible dust in your plant and the associated risks. This training takes several forms:

• General safety and hazard awareness training for all affected employees
• Job-specific training about combustible dusts in staff work environments
• Ongoing refresher training

Once again, this training must be documented. If you fail to comply with NFPA standards, you aren’t just risking being fined. You’re risking an explosion that could put your plant and your personnel in jeopardy. Hopefully that’s not a risk you’re willing to take. Nilfisk has been helping food processors keep their plants safe from combustible dust for more than 55 years. Learn more about Nilfisk industrial vacuums for food facilities.