Dust is a natural and inevitable part of grain operations which is created by moving grain, it can accumulate on surfaces and lie undisturbed for many years. No amount of dust is safe, in fact; accumulated dust as thick as a piece of paper is enough to lead to an explosion.
Grain dust explosions can results in loss of facilities, significant operational down time and of course human fatalities and injuries. 111 Combustible dust incidents caused 337 injuries and 66 deaths in the Unites States between 2016 and 2017, according to data from the Chemical Safety Board. So what causes dust explosions and what can be done to prevent it?
The Dangers:
Five components are required for a grain dust explosion to occur. The first three elements are required for a fire consists of; Fuel (Combustible Dust), Heat (Ignition Source) and Oxidiser (Oxygen in the air). The other two elements that must be in place for a dust explosion to occur include; dispersion and Confined Space.
It is important to understand the difference between the primary and secondary event. The primary event consists of an initial explosion or fire which shakes dry dust loose and ignites it, this could be a very small event in and of itself. The pressure caused by the primary event travels throughout a factory or plant and dislodges dormant dust which fuels a secondary explosion – most injuries, damage and fatalities are caused by the secondary explosion.
Prevention:
Grain dust explosions were reduced by 47% in the first year of implementing the 1987 OSHA Grain Handling Facilities Standard because of an increased awareness of and attention to identifying and managing hazards associated with entry into tanks, silos and bins as well as grin dryer fires.
All management and operational staff needs to be aware of and trained on dust hazards and thereof:
· Hazardous Area Classification needs to be conducted
· A hazardous dust control program should be created and implemented
· Staff training on managing hazards
Possible ignition sources needs to be identified and managed:
· Ensure that appropriate electrical equipment and wiring methods are used
· Control open flames, sparks and static electricity including mechanical sparks and friction.
· Implement ignition control program for dissipating any electrostatic charge generated while transporting dust through ductwork.
· Smoking should not be allowed
· Heated systems and surfaces should be kept away from combustible dust.
· Temperature monitors can be installed on bearings on a bucket elevator, to prevent the possibility of a spark from an overheated bearing
Dust needs to be managed:
· Facilities should be equipped with proper dust collection systems and filters
· Dust inspections should be conducted regularly
· Good housekeeping needs to be maintained at all times
· Turbulence of grain at transfer points should be avoided during loading and unloading
· The angle of spouting can be adjusted to reduce grain speed as it moves from one bucket elevator to another conveyor.
Safety directors in grain handling facilities balance multiple hazards and, in some cases, prioritizing housekeeping and equipment maintenance can be challenging. Further, having safety standards and implementing these standards consistently can be an obstacle. It is advisable that these functions are outsourced to agencies specializing in this field to ensure that optimal results are achieved without diverting focus and resources away from actual operations.
Globally grain dust explosions have decreased in Grain Operation Industries through increased awareness of dust hazards, enhanced engineering controls and interventions as well as improved grain handling methods, but they do still occur. Until we reach the goal of zero grain dust explosions, Ottalaus will continue our effort of increasing awareness of grain dust hazards, providing trainin, preventive tools, and best practices. Ottalaus offers Training services, Hazardous Area Classification, Explosion Prevention Equipment Management and Continuous Compliance Services which all aid in the prevention of combustible dust explosions.
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