In today’s episode of the Dust Safety Science podcast, Adam Haroz, Director of Engineering with Conversion Technology Inc. and Alysha Yinger, Director of Engineering at RoboVent, go over the importance of grounding and bonding in dust collection systems.
The discussion will cover two main angles: the dust hazard analysis perspective and the dust collection design implementation standpoint. Topics include common deficiencies in grounding and bonding, and how to address these issues if identified.
How Common Are Grounding and Bonding Deficiencies in Dust Collection Systems?
Adam said he frequently encounters bonding and grounding deficiencies in Dust Hazard Analyses (DHAs). He often explains to site managers that static electricity, which he refers to as the “silent killer,” can be present without detection. It can permeate systems without operators being aware of its presence or potential danger.
In the bakery processing sector, he often sees issues with the bonding of bulk trucks, particularly during the unloading of bulk flour and sugar. These trucks are usually not clamped, as required by NFPA standards, which is essential to ground the trucks and prevent static transfer through the line. Recently, a facility experienced a silo explosion due to static transfer because their trucks were not properly clamped.
Adam also noted the frequent use of improperly rated bulk bags and the use of flexible connections (pipes, hoses) that are either not properly bonded or lose their bonding effectiveness over time. This is especially prevalent in bakeries and flour processing, as well as in 3D printing, metal dust, and battery manufacturing, where low-energy ignition potential is a significant concern.
On the preventative maintenance (PM) side, he said that while units are usually well-built and grounded initially, the verification of bonding over time is often neglected. When asked about their bonding and grounding PM procedures, most sites do not have any in place. In Adam’s view, ensuring that bonds are verified and maintained is a critical issue.
Alysha explained that as a dust collector manufacturer, it is essential to ensure that RoboVent units are properly bonded and grounded before they leave the facility. This involves making sure all metallic components and the housing, including filters, intake, and exhaust components, have electrical continuity. This is done by examining all powder-coated finishes, bolted connections, thread-forming screws, and thread-cutting screws to ensure proper connectivity throughout the unit.
Once the unit is sent and installed on-site, it undergoes further testing with meters to confirm that all connection points are functioning correctly. Additionally, manufacturers pay close attention to sourcing the right components for the dust collector, particularly when dealing with combustible dust.
She added that filters and filter media are crucial in managing static electricity within dust collectors. For combustible or highly ignitable dust, static dissipating filters are used. These filters are made from conductive or semi-conductive materials that allow static to flow across the media and dissipate safely, preventing the dust collector itself from generating a static charge. Ensuring the use of static dissipating filters is vital for the safe operation of dust collection systems.
What Should Clients Know About Maintaining Bonding?
Alysha emphasized that ensuring proper connectivity is not limited to the initial installation of the dust collector. Each time a filter is changed, the system is altered, or a gasket is reseated, it is essential to retest the connectivity between surfaces. This includes adding or removing components. Regular testing after any changes ensures that the system maintains proper electrical continuity and safety.
Where Else Do Challenges Appear?
Adam emphasized the importance of bonding and grounding preventive maintenance (PM) programs. He frequently encounters issues with flexible connections, especially in the food industry, where flexible lines are used instead of metal ducts. People often prefer flexible lines to avoid the rigidity of metal ducts and due to concerns about potential sparks from metal screws.
However, Adam pointed out that if these concerns exist, other safety measures need to be evaluated. Flexible connections require specific attention, such as using green ground wires and following OEM recommendations to wrap the wire around each coil of the flex line. It’s crucial to ensure the internal bonding coil makes physical contact with the couplings at the ends, as the bond is ineffective otherwise.
Adam emphasized that equipment moves and vibrates, and lines get replaced, which can affect bonding. He advises maintenance teams to include bonding checks in routine inspections and to educate operators about its importance. While metal ducting is preferred for its reliability, flexible connections must be properly bonded and grounded.
He often finds that large-scale bonding and grounding, like lightning protection for grain silos, are handled well, but smaller issues, such as truck bonding, are frequently overlooked. Trucks often lack bonding, and ground rods may be missing, posing significant risks. Static electricity from powder moving through ducts can cause a static charge, which, if not properly managed, can lead to dangerous discharges and potential explosions.
Adam also stressed the need for regular communication with operators, who may notice sparks and other issues that indicate bonding problems. Proper bonding and grounding of lines prevent static charges from causing severe problems in the system.
What Does a Good Preventative Maintenance (PM) Look Like?
Adam emphasized the importance of regular visual inspections for static dissipative mats. He often sees ground wires being kicked off because they are just small wires. While it may not be necessary to perform preventive maintenance (PM) frequently, he recommends conducting visual inspections each shift, day, or after use to ensure the wires remain properly connected. This simple check can help maintain the effectiveness of the safeguard and prevent potential issues.
Alysha noted that in industrial ventilation, the management of change is crucial. Systems often start with the best intentions and installations but can deteriorate when changes occur without proper checks. For example, altering ductwork, moving drops, or reconnecting components without verifying the integrity of connections can lead to issues. Gaskets may be incorrectly reapplied or replaced with incompatible materials, breaking the connection. Vibrations and corrosion can also loosen connections over time, especially in older or outdoor dust collectors.
She emphasized the importance of preventive maintenance (PM) inspections. While operators can perform visual checks, more in-depth inspections with an ohmmeter should be done by maintenance personnel. Regular checks ensure that connections remain secure and that bonding wires are properly connected. Alysha stressed that visual inspections need to be frequent because minor disturbances, like a cleaning crew accidentally dislodging a cable, can cause bonding failures.
She also mentioned the importance of clamping trucks correctly during unloading. It’s essential to verify that the trucks are properly clamped and that hoses are static dissipative according to standards. This verification should be part of the unloading procedure to ensure safety and compliance. Having a documented procedure and ensuring adherence to it is critical for maintaining system integrity and safety.
Are Static Dissipative Hoses a Challenge?
Adam emphasized the importance of bonding and grounding preventive maintenance (PM) according to NFPA 77, which outlines the needs and rules for static electricity but leaves the frequency of checks to the site, based on their Dust Hazard Analysis (DHA). He recommends that standard manufacturing facilities check bonding and grounding PMs annually. He suggests using ohm meters to check bonds during OSHA-required annual lockout/tagout audits. This can be done at the equipment or motors.
He stresses the need to include verification of internal bonding in PMs and standard operating procedures (SOPs), especially for dust collectors. Every time maintenance is performed, such as filter changes, it’s crucial to ensure proper clamping and bonding. He notes that verifying bonds can take just a few seconds with an ohm meter to check resistance across points.
Adam advises increasing the frequency of checks for systems handling metal dust or low ignition energy materials. He also recommends more frequent checks for areas with ESD mats or where human static electricity could cause ignition.
He points out that flexible hoses, especially in food material unloading, should be checked for wear and tear. Personnel should verify that bonding wires through insulation are not damaged. He compares this to ensuring a repaired pipe with duct tape still maintains negligible resistance across the duct.
In summary, Adam highlights the need for regular and thorough checks of bonding and grounding systems to prevent static-related hazards, ensuring these systems are maintained properly and consistently.
Chrus: [26:56] So yeah, you got it. Awesome. I think we’ll close up. Any on any final words, Alysha? Anything else that we didn’t cover that you think is important to discuss in terms of grounding and bonding and these types of systems?
Conclusion
Both Alysha and Adam emphasized the importance of effective bonding and grounding practices to ensure the safety and functionality of dust collection and ventilation systems. Alysha pointed out that while the topic may seem overwhelming, it can be managed by breaking it down into manageable tasks and working closely with your team and manufacturers. This involves conducting regular visual checks, annual preventive maintenance, and feeling comfortable with the system’s requirements and procedures.
Ultimately, ensuring the reliability of bonding and grounding systems requires a combination of regular maintenance, detailed procedures, and a proactive approach to safety. By following these guidelines, companies can effectively manage their dust collection systems and mitigate the risks associated with static electricity.
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Alysha Yinger and Adam Haroz directly:
Website: https://www.robovent.com/
LinkedIn: https://www.linkedin.com/in/alyshayinger
Email: [email protected]
Website: https://www.conversiontechnology.com/
LinkedIn: https://www.linkedin.com/in/adam-haroz-eit-lmss%E2%84%A2-1a902727/
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
Conversion Technology Inc
RoboVent
Standards
NFPA 77
