Sugar Dust Explosion Prevention & Protection
Sugar presents a combustion hazard when it is in a dry & dusty form. A fine sugar dust explosion can generate a pressure in excess of 100 psi within enclosed process equipment in less than 100 milliseconds. Industry is provided with recently updated tools to manage such risk in the form of Standards published by The National Fire Protection Association (NFPA).
The NFPA Standards covering explosion prevention and protection (68-2007, 69-2008, 654-2006) require that a documented risk program be in place for all combustible dust hazards. The OSHA National Emphasis Program on combustible dust processes released on 18th October 2007 underwrites the full requirements of these NFPA Standards.
The owner / operator of a sugar dust processing or handling facility is faced with choices in the safety measures that can be combined to meet the requirements of these Standards. One or more of the following approaches to safety must typically be employed:
- Housekeeping Measures: Eliminate or minimize combustible dust accumulation by design or controlled operating procedures.
- Equipment Grounding & Appropriately Rated Electrical Systems: Eliminate or minimize the build up of static electricity & periodically inspect that such measures remain effective, combined with the use of electrical systems designed for the hazardous area in which they are applied
- Equipment Venting: Discharge the products of combustion from a dust explosion to atmosphere safely in order to contain the pressure generated inside protected equipment below safe design limits
- Ensure the flameball generated by venting can be accepted
- Utilize ‘flameless venting’
- Utilize ducting to atmosphere when equipment is indoors
- Equipment Isolation: Introduce barriers to flame propagation that can prevent a primary dust explosion from amplifying into a typically much more severe secondary event
- Implement appropriately rated rotary air locks
- Implement appropriately designed screw conveyors
- Implement mechanical isolation barriers
- Pinch Valves
- Knife Gate Valves
- Implement chemical isolation barriers (particularly well suited to large and irregular ducting)
- Equipment Suppression: Prevent the development of a dust explosion by detecting its earliest stages and extinguishing its progress by the injection of an appropriate quenching agent
- Spark Detection: Optically detect the presence of hot particles in a pneumatic air flow or conveyor belt before they reach process equipment within which they become a source of ignition
The following types of process equipment are typically found where sugar dust is processed or handled:
- Filters / Dust Collectors
- Vertical Conveyors (e.g. bucket elevators)
- Horizontal Conveyors (e.g. belt conveyors)
- Silos, Bins & Hoppers
Where sugar dust and air are mixed together in a confined space, the consequences of a dust explosion are the greatest. Filtration equipment handling a combustible dust almost certainly contains a hazardous concentration of material under normal operating conditions. Other items of equipment may only temporarily carry a ‘combustible load’ of hazardous material, perhaps during start up, shut down, loading or unloading. However, while that combustible load is present, the risk is no less severe. If the potential for a combustible load cannot be eliminated, protection measures are required.
There are always choices regarding the sugar dust explosion prevention and protection strategy employed. For personal attention, please contact our experts:
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