Ashok: Combustible dusts are ranked into one of four classes; ST0, ST1, ST2, ST3. The level of explosion violence increases with the class number. The only dust that has zero risk of explosion is an ST0 dust. All other dusts have an explosion hazard.
What is a Class II dust?
A Class II, Division 1 location is a location. (1) In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or. ignitible mixtures, or. (2) Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible.
Which is a term used to describe a dust explosion?
What is deflagration? Deflagration is a term often used to describe combustible dust explosions. In a dust explosion, the deflagration processes happens so rapidly that the heated air and gaseous fire products (such as carbon dioxide) produce extreme air pressure that can blow out walls and destroy structures.
What is dust classified?
According to the “Glossary of Atmospheric Chemistry Terms” (IUPAC, 1990), “Dust: Small, dry, solid particles projected into the air by natural forces, such as wind, volcanic eruption, and by mechanical or man-made processes such as crushing, grinding, milling, drilling, demolition, shovelling, conveying, screening.
What is the dust explosion pentagon?
The dust explosion pentagon is an expansion of the fire triangle as it relates to dust. The fire triangle starts with fuel, oxygen, and an ignition source. So if you have these three elements at the same time, you can get a fire.
What is KST & Pmax?
Kst value and Pmax are explosive properties measured in the laboratory to quantify the severity of a dust explosion. A weighed quantity of combustible dust is placed into the dust container. The main explosion chamber is then evacuated to 0.4 bar absolute.
What is a Class 1 Div 1 area?
Class I, Division 1 classified locations. An area where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions. A Class I, Division 1 area encompasses the combination of Zone 0 and Zone 1 areas.
What makes dust explosive?
Dust explosions are the result of high concentrations of combustible dust particles rapidly combusting inside an enclosed space. This will mix the dust with the oxygen in the air, which will make the explosion bigger, and potentially fuel a second dust explosion – or even several.
Why is dust explosive?
Dusts have a very large surface area compared to their mass. Since burning can only occur at the surface of a solid or liquid, where it can react with oxygen, this causes dusts to be much more flammable than bulk materials.
What is dust class M?
Dust class M: All wood dust and dust originating from repair compound, filler and clear coats, plaster, cement, concrete, tile cement and paints such as latex and oil paints or quartziferous materials such as sand and pebbles.
What are the 5 elements of a combustible dust explosion?
Five elements must be present for a combustible dust explosion to occur: fuel, oxygen, an ignition source, dispersion and confinement.
Is a St Class 1 dust dangerous?
The only dust that has zero risks of the explosion is a St 0 dust. However, all other dusts have an explosion hazard including the St 1 dust which can compromise containment on a piece of equipment, or blow out the walls of a building. Grains, Sugar, Fluor, etc. all fall in St class 1 dust.
What are some examples of combustible dust?
Examples of combustible dust: Metal Dust – Such as Aluminum and Magnesium. Wood Dust. Coal and Other Carbon Dusts. Plastic Dust and Additives. Biosolids. Organic Dust – Sugar, Flour, Paper, Soap, Dried Blood (e.g., slaughterhouses) Certain Textile Materials.
What is an explosive dust?
Explosive Dust is a mix of combustible or explosive substances in the form of dust that mixed with air (oxygen), after ignition, cause the reaction to spread to the noncombusted materials.
