In today’s episode of the Dust Safety Science podcast, Matt Williamson, Director of Engineering at ADF Engineering, reviews how facility owners and managers can protect their hammer mills as per NFPA requirements.
Matt Williamson has been with ADF for 16 years. In addition to his current role, he has also held the position of Safety Director, where he specialized in process safety. Over the past decade, his primary focus had been on combustible dust safety- he has been involved in over 100 dust hazard analyses, working predominantly with agricultural sectors like food, feed, fuel, and pharma.
Matt’s work often intersected with industries dealing with grains, sugars, and starches, particularly those that involved concrete silos. He explained that these silos, while vital for agricultural storage, posed unique challenges when it came to protecting against combustible dust hazards, and past incidents had shown the potential for catastrophic outcomes.
What Are the Challenges in Protecting Hammer Mills, Particularly in Feed and Food Applications?
Matt explained that hammer mills, especially those used in dry corn mills, present significant safety concerns, particularly in older facilities where the equipment is not well-protected. Many of these hammer mills were installed in cramped spaces, which makes it difficult to retrofit them with isolation devices.
The close proximity of these mills to dust collectors also pose a major hazard. Matt described how hammer mills rely on large volumes of air to remain cool, and dust collectors compromise this need when installed too close to the mills. Since hammer mills are frequent sources of sparks, this situation creates a perfect environment for fires or explosions when dispersed dust is present.
Is Space Limitation a Major Challenge When Isolating Fire or Explosions in Older Mills?
Space limitations are indeed a significant problem, particularly in older facilities where hammer mills were often grouped together. Matt explained that the layout in many facilities create a “domino effect,” where an explosion in one mill could trigger explosions in neighbouring mills. This is due to the fact that air intakes connect the mills. When one mill experiences an explosion, the fireball could quickly spread to adjacent mills through the air intake system.
In addition to these challenges, Matt noted that some mills were placed directly under storage bins, further increasing the potential for catastrophic events. In such cases, even when precautions are taken, the physical location of the mills often mean that an explosion could damage both the mill and the bin above it.
What Are Some of the Solutions for Protecting Hammer Mills from Combustible Dust Hazards?
Matt outlined several solutions for protecting hammer mills from combustible dust hazards. While the NFPA 654 standard listed multiple options, not all of them are practical for hammer mills. For instance, reducing oxygen concentration isn’t feasible because hammer mills require airflow for cooling. Similarly, explosion venting is difficult to implement due to the limited space available on the surface of the mills.
The most common solutions Matt recommends are either chemical suppression systems or fast-acting isolation valves. Chemical suppression systems, which are usually activated by spark detection, are installed to suppress explosions inside the mill. In situations where space is limited, fast-acting isolation valves are an alternative, though they tend to be expensive and require independent structural support due to their weight.
Matt also emphasized the need to address air intake lines, which could propagate explosions into other areas. Ideally, he recommends placing hammer mills outside of the main facility or in separate rooms to minimize the risk.
How Are Smouldering Events in Hammer Mills Addressed, and What Are the Best Practices for Recovery?
Matt also discussed the challenges of smouldering in hammer mills, which often occur when materials inside the mills heat up and smoulder, leading to deflagration events if not managed correctly. He stressed that thorough cleaning was critical after any smouldering event. Mills should be taken apart, screens and hammers inspected, and any damaged parts replaced before restarting the equipment.
He recommended using infrared or spark detection devices to monitor hammer mills and to shut down material flow if smouldering was detected. However, Matt cautioned that shutting off airflow wasn’t always a simple solution. Leaving the airflow on could help cool the mill, but it also has the potential to spread fires. Each scenario needs to be carefully assessed to determine the best course of action.
What Is the Key to Hammer Mill Safety?
Matt concluded by emphasizing the importance of location when it comes to hammer mill safety. He likened the placement of a mill to real estate: its location is critical. Hammer mills need to be positioned carefully to ensure that any fireball or explosion will not impinge on walls, ceilings, other equipment, or personnel. The placement of air intakes is especially important, as these are often the first areas to be affected in the event of an explosion. Matt recommended that mills be isolated from other equipment and personnel to reduce the potential for catastrophic events.
Conclusion
Ensuring safety in combustible dust environments, especially around hammer mills, calls for a proactive approach. Matt’s experience confirms the need for facilities to prioritize safety not only through retrofitting but by rethinking the entire setup of these systems. Proper placement, isolation, and modern suppression techniques are vital to reducing risks.
As industries continue to evolve, so too must their safety practices. By embracing new strategies and solutions, companies can protect their workers and equipment, mitigating the threat of dangerous incidents before they occur. The path forward involves making thoughtful, well-planned decisions that build a stronger foundation for the future.
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Matt Williamson directly:
Website: http://adfengineering.com/
LinkedIn: https://www.linkedin.com/in/matthew-williamson-760111215/
Email: [email protected]
If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.
Resources mentioned
The resources mentioned in this episode are listed below.
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Companies
ADF Engineering
Standards
NFPA 654
Download the episode
DSS283: Protecting Hammer Mills as per NFPA Requirements with Matthew Williamson
