Our Process Safety and Dust Hazard Analysis (DHA) assist companies that are affected by NFPA 652 to comply with this standard of the National Fire Protection Association (NFPA). NFPA 652 addresses the fundamental requirements for managing the hazards of combustible dusts. This includes complying with the other NFPA standards that are related to combustible dusts, in addition to meeting the challenges of the Occupational Safety and Health Act (OSHA) standards that involve control of combustible-dust hazards.
Through our accredited laboratory testing facilities and a world-class team of senior process safety specialists with extensive applicable expertise, we are uniquely positioned to assist our clients with all the expert services necessary to be in full compliance with the requirements of NFPA 652. We have been conducting specialist Dust Hazard Assessments (DHA), which is now a requirement of NFPA 652, for more than three decades for our clients in the Americas, Europe, and the Asia Pacific. Specifically, our DHA services related to NFPA 652 include:
- Hazard Identification – Identifying the locations and equipment where explosion and flash-fire hazards could exist, involving fine particulate solids and dusts
- Laboratory Testing – The Dust Hazard Assessment is to be based on the results of tests on materials that are representative of the combustible particulate solids and dusts that are present in the equipment and could be present in the workplace. This requires that representative dust samples be collected from appropriate locations using acceptable methodologies to preserve the properties of the sample. The determination of explosibility, ignition sensitivity, and explosion severity of dusts is then to be determined in accordance with applicable methods such as ASTM test standards. The typical tests that should be considered include:
- Go / No Go Screening
- Maximum Explosion Pressure (Pmax) and Deflagration Index (Kst)
- Minimum Explosible Concentration
- Limiting Oxygen Concentration
- Minimum Ignition Energy
- Minimum Ignition Temperature (Dust Cloud & Dust Layer)
- Burning Behavior (BZ)
- Powder Chargeability
- Volume Resistivity and Charge Relaxation Time
- Dust Hazard Analysis (DHA) – DHA is required if materials handled and processed have been identified as combustible and/or explosible. DHA is a systematic review to identify and evaluate potential fire, flash fire, and explosion hazards associated with the presence of combustible particulate solid(s) in a process or facility. DHA must be conducted by an expert with demonstrated ability to deal with hazards related to processing and managing combustible particulate solids. For existing processes the owner/operator shall schedule the DHA to be completed within three years of the issue date of NFPA 652. For new construction or modifications in excess of 25% of original cost, DHA shall be completed as part of the project.
- Dust Hazard Management – Owner/operator of the facility with potentially combustible dust shall be responsible for managing the fire, flash fire, and explosion hazards that are identified by the Dust Hazard Analysis (DHA). NFPA 652 prescribes approaches for the management of combustible dust hazards. Consideration shall be given to:
- Building design
- Equipment design
- Ignition source control
- Personal protective equipment
- Dust control
- Explosion prevention/protection/Isolation
- Fire protection
- Prescriptive-Based Design [Chapter 8] – The designs and operations of buildings, structures, and equipment are to include specified features to minimize the likelihood of fire and explosion.
- Design Features – These include design of process and conveying systems for containment of dusts, housekeeping to prevent dust accumulations, dust-collection systems, control of ignition sources, explosion venting or other methods for mitigating the effects of explosion, fire protection systems and extinguishers, and personal protective equipment.
- Performance-Based Design [Chapter 6] – As an alternative to a prescriptive procedure for the control of combustible-particulate hazards, a performance-based design could be undertaken by one of our qualified specialists. The basis for the alternative design shall include documented properties of materials, and documentation of calculations, references and sources, and assumptions, including their limits of applicability.
- Life Safety – The performance-based design requires an evaluation of methods that are provided to reasonably protect occupants of a structure from the effects of fire and explosion for the time needed to reach a safe location. The methods can include the prevention of ignition of mixtures of combustible dusts in air or assurance of a structurally-sound and adequately-protected evacuation pathway.
- Scenarios – The performance-based design requires the evaluation of at least six fire scenarios and at least four explosion scenarios, with the objective of assuring life safety, preventing the spread of fire, and preventing explosion damage.
- Management Features – The management of dust hazards is to include operating and safety procedures that control combustible-dust and ignition hazards, a system for inspections and tests of dust-control systems and devices, and other process-safety aspects that are similar to those of the OSHA Process Safety Management standard.
Our senior process safety specialists are uniquely qualified to evaluate the adequacy of existing controls of dust hazards and to propose practical recommendations for any needed improvements. This includes the identification of possible fire and explosion scenarios and to evaluate the existing or proposed hazard-mitigation systems and equipment, to attain the required life-safety and combustion-prevention objectives.