1ToxStrategies, San Rafael, CA
Manny Dekermenjian, PhD, PE, CFEI
Combustible dust hazards at a facility are difficult to evaluate, and operators often need help
determining whether their facility has the necessary measures in place to mitigate the hazards. This study describes a combustible dust investigation.
Situation / Problem:
Facility operators want to know if they have a combustible dust hazard at their facility and if they
need to change or add any equipment or procedures to operate more safely. They also want to know
which industry standards or regulations affect them, particularly new standards focused on
combustible dust. To answer these questions, a site inspection is required, wherein the investigator
learns about all the processes and procedures that might involve combustible dust.
A detailed understanding of the various processing steps in the facility, and the standard procedures, is needed to complete a dust hazard analysis. Dust samples can be collected at locations that accurately represent the properties of the dust in a specific area. Workplace dust is mitigated by regular housekeeping and engineering controls to prevent dust from leaving the process. Calculating the concentration of suspended dust within duct work or through air-moving devices can help characterize the extent of the potential hazard. Dust samples can be analyzed in the laboratory to characterize several physical properties that are important in understanding the potential hazard. Several test methods are available: ASTM E1226 - Go/No-Go test; ASTM E1515 - Minimum Explosive Concentration; ASTM E1226 - Explosion Severity; ASTM E2019 - Minimum Ignition Energy; and ASTM E1492 - Minimum Ignition Temperature.
Results / Conclusions:
The laboratory results on the dust samples will determine whether the dust at various parts of the
facility is combustible. If none of the dust is combustible (Go/No-Go test), then there may not be any need to incorporate additional safety measures. If the dust is combustible, as is often the case for dusts composed of organic material, then additional information should be gathered, examples of which are described below. The locations and types of dust collectors in use will determine whether the combustible dust is being handled appropriately. Air-moving devices are potential ignition sources as combustible dust is conveyed through duct work. The dust concentration can be calculated under various operational scenarios and compared to the minimum explosive concentration. If the concentration of dust is close to or above the concentration required for ignition, then intrinsically safe air-moving devices may be required. The amount of dust in the workplace is an indicator of the potential hazard posed by secondary-dust explosions. The various aspects of operations should be considered in the investigation, such as startup, shutdown, maintenance, housekeeping, cleaning, and normal operations.
Hazard Prevention Engineering
Indoor Environmental Quality/Indoor Air Quality
Risk Assessment and Management
Acknowledgements and References
List any additional people who worked on the project or provided guidance and support along with details on the role they played in the research. (Please include first name, last name, organization, city, state and country).
What learning level(s) is the presentation content geared towards?
Novice - new to the job, role, or task, with no or limited knowledge of the content.