If combustible dust led to an explosion at your facility, how would your company continue to produce product, get supplies, and maintain the flow of goods or services to its customers? With confinement of the propagating flame front, pressure will rise which may cause rupture of the enclosure. The table on page 72 summarizes the explosions and known sources recorded in 2015, 2016 and 2017.
Ignition This is what actually causes the other elements to combust and create a dust explosion. For a fire to be able to burn it needs to have three things present simultaneously: Ducts should be short and straight or the efficiency of venting can be greatly reduced.
Employers with hazardous chemicals including combustible dusts in their workplaces are required to comply with 29 CFR 1910.
When loading and unloading, the focus should be to avoid turbulence of grain at transfer points to minimize dust separation from the grain stream. This often occurs inside or near running machinery in processing operations.
This could involve designing the equipment to withstand the pressure of an explosion or by providing suitable venting. Combustible dusts become more dangerous as particulates become finer. Industries producing dust as a product tend to be more aware of the hazards than industries that produce dust as a by-product. A primary explosion occurs when the dust cloud is ignited by an external source such as heat, sparks, or open flame.
If interested please contact Professor Gretchen Mosher gamosher iastate. Several options exist to prevent excessive accumulation of grain dust. Another method for controlling dust is to adjust the angle of spouting to reduce grain speed as it moves from one bucket elevator to another conveyor. A dust fire occurs when a fuel, in this instance a combustible dust, comes in contact with an ignition source in the presence of oxygen, contained in the air.
It states that fuel, oxidant, and an ignition source must be present for a fire to occur. Although the explosion protection approach of venting reduces the amount of confinement, care is needed to size vent panels appropriately to avoid equipment failure.
Members receive a full listing in the directory and are featured on the database homepage and incident pages. The joint investigation report 1 indicated that a fire initiated in a shell molding machine from an unknown source and then extended into the ventilation system ducts by feeding on heavy deposits of phenol formaldehyde resin dust.
These property loss prevention measures would be in addition to the in-house process safety reviews that are required under the European ATEX directive. About 30 grams per cubic meter is the lower explosive limit for most flammable dusts. Combustible Dust Hazard Requirements Fire, flash-fire, and explosion hazards must be considered in any industries handling, manufacturing, or transporting combustible dusts.
Both of these combustible dust hazards have amounted to substantial loss in processing industries and elsewhere. Within milliseconds, the system discharges an extinguishing gas or powder into the equipment during the earliest stages of the developing explosion to stop it before damaging pressures develop.
Dispersion This is when the accumulated dust is spread out over the air and creates a dust cloud.