Thank you
This live web event has ended. Thank you for attending.
Description
| Deflagration Hazards and OSH Act Compliance | |
| John discussed the importance of managing deflagration hazards to prevent facility explosions. They emphasized the obligation of facility operators to comply with nationally recognized consensus standards, such as those set by the NFPA, due to the OSH Act of 1970. John highlighted that these standards are not explicitly adopted by federal law, but are effectively required due to the OSH Act. They also mentioned the publication of six standards focused on combustible dust hazards, with an emphasis on NFP A 652, the fundamental standard. John further discussed the management of hazards through either a performance-based or prescriptive design approach. They explained that the choice between these two approaches depends on the hazard and the goal. | |
| Deflagration Prevention and Management | |
| John discussed the prevention and management of deflagrations, emphasizing the importance of controllable ignition sources and sufficient concentration of flammable dust suspended in an oxidizing medium. They highlighted the unique challenges posed by alkaline metals and the need for special handling. They stressed the importance of maintaining clean interior walls to prevent dust accumulation and outlined the requirement for processes and equipment to be designed by a qualified person. John further discussed the need for preventing the movement of combustible solids through fans, the requirement for smooth bends in ducts, and the need for all electrical equipment to comply with the national electrical code. They also highlighted the need for explosion prevention and isolation in processes involving combustible dust. | |
| Electrical Safety and Material Separation | |
| John discussed the importance of using magnetic separators and screens for material separation, particularly with iron ores, and the role of static management in preventing electrical hazards. John emphasized the need for a low impedance path between ducts for bonding, with a personal preference for a lower impedance for safety. They stressed the significance of grounding all systems to prevent electrocution and outlined the need for strategies to prevent static hazards as per Nfpa 654. John highlighted the importance of equipment maintenance according to the manufacturer's instructions and the potential risks of neglecting this, including equipment breakdowns, ignitions, and frictional heating. They concluded by underscoring the need for a management of change program to ensure that any modifications to the process or material do not increase the probability of ignition. | |
| Temperature Calculation and Fire Prevention in Combustible Dust Facilities | |
| John discussed the calculation of maximum temperature in a system with a single bearing failure. They explained the relationship between energy input and output, emphasizing the role of friction in converting electrical energy into heat. John outlined the factors influencing temperature change and demonstrated how the Stefan-Boltzmann relation is used to calculate temperature increase. They also suggested a possible solution to prevent particulate ignition, such as using a motor with a lower horsepower rating, and highlighted the importance of performance-based design and other strategies to manage hazards in combustible dust facilities. John also touched on the importance of the electrical code in preventing electrically initiated fires. | |
| Hazard Management and Safety Measures | |
| John expressed their skepticism regarding the significance of particle size in distinguishing fibers and flyings in hazard management. They stressed the importance of designating materials as class 2, division one or division 2, based on their ignition and dust concentration. John further elaborated on the implications of class 2 division 2 hazardous locations, the need to avoid C. 2D. 2 enclosures, and the importance of upgrading electrical boxes due to increased dust accumulation. They also underscored the role of cleaning frequency, the potential replacement of electrical boxes, and the limitations of operating powered industrial trucks in such areas. John highlighted the importance of maintaining HVAC systems free of dust to prevent dust accumulation and the risk of deflagration. They also emphasized the need for a hot work program and explosion prevention control measures. John noted that they had only covered half of their prepared slides, indicating a need to speed up the discussion. | |
| Explosion Prevention in Building Compartments | |
| John discussed the importance of preventative measures for explosions in process equipment within building compartments, focusing on controlling concentrations of particulates in the air. They highlighted the 25% limit of Mec as a safety margin, established by the Technical Committee. John emphasized the role of airflow and particulate generation rate in preventing explosions. They also mentioned the importance of protecting employees from the air material separator and the criticality of calculating the concentration of fines in the air for particle size analysis. John stressed the need for diligence in identifying the worst case, bounding value quantities, and maintaining the explosion prevention strategy according to the criteria in NFPA 69. They also discussed the management and maintenance of dust collectors, including the use of pressure differentials and industrial timers to limit the concentration of dust during cleaning. | |
| Particle Heat Transfer and Combustible Dust Concerns | |
| John discussed the heat transfer mechanisms among particles in a suspension, emphasizing the role of radiation in heating particles. They explained the process of calculating the upper deflagrable concentration, which is the point at which the concentration of combustible dust in the air becomes a risk. The calculation assumes that the dust does not displace any air. John used this calculation to address concerns about combustible particulate in silos, explaining that by eliminating all ignition sources and admission sources, the risk of ignition can be significantly reduced. | |
| Dust Control and Safety Measures | |
| John discussed the importance of preventing dust accumulation in building compartments to ensure occupant safety. They highlighted the need for proper dust control systems, a safe collection point, and a comprehensive housekeeping program. John emphasized the significance of managing dust release at its source, avoiding open pouring and transfer operations, and ensuring bagging operations are conducted under negative pressure. They also discussed the design of hoods and dust collectors, emphasizing the importance of required airflow rather than the fan package. John underscored the challenge of capturing chips from cutting machines and the importance of careful design to overcome the chip's momentum. They also discussed the process of designing a collection system for certain equipment, emphasizing the importance of calculating airflow from each food source and adjusting duct diameters to maintain equal and sufficient pressure. John stressed the criticality of managing and preventing fugitive dust accumulation to avoid dust explosions and ensure cleanliness and safety standards. They also discussed the use of flame-resistant garments (FRG) in the context of Nfpa 2112 standards, emphasizing their limitations and the importance of conducting a workplace hazard assessment to determine where FRG is needed. |