A material that is combustible will burn very easily when it is very finely divided, like in the form of dust. When there is a concentration of such dust in the air, under certain conditions, it can cause an explosion. Materials, like iron and aluminium, which under normal circumstances will not burn as large pieces, become combustible if they are in the air in the form of a dust. Fume and dust extraction systems can help remove the material from the air such as those supplied by Dust Extraction Online.
Many manufacturing and other production processes, do cause a lot of dust to be created, and when this dust becomes combustible it can cause explosions that lead to injuries and deaths among workers. This can happen in food industries that have candy, feed, flour, starch, spice, grain and sugar. It is also very prevalent in industries like tobacco, coal, dyes, pharmaceuticals, pesticides, rubber, paper and paper pulp, wood and plastic. Metal industries like those of aluminum, zinc, magnesium, iron and chromium are not immune to the production of fine dust that can become combustible.
Any fire requires oxygen, heat and fuel, and dust can become a fuel when it is in very fine form, and the air and heat in a workplace provide the other conditions for fires to ignite spontaneously. This process of deflagration quite often occurs in confined workplaces, or in process vessels or equipment, and invariably results in a rise of temperature and pressure that leads to explosions. This is the dust explosion pentagon formed by air, fuel, heat, confinement and dispersion. Dust explosions will not occur if one of these five conditions is not present, and allows safety engineers to find ways to prevent explosions that can be life threatening in a workplace.
Most workplace explosions become still more dangerous, because they lead to secondary explosions, where dust that has earlier accumulated on various surfaces can get dislodged by the original explosion, and get ignited. These increased quantities of combustible dust make such industrial hazards far more potent. That is why it can be very important to implement proper housekeeping in any industry that contains these hazards by constantly inspecting for combustible dust, testing it and then controlling it by frequent removal. The installation of dust collection systems with filters and proper ventilation can go a long way in increasing safety in workplaces. It can also help if the dust is prevented from escaping during the process, with ventilation systems, strategically placed to collect all dust. Surfaces, both horizontal and vertical, must be treated in such a way that they do not allow dust to collect. Care must be taken to see that any equipment used to collect and remove the dust is also not a source of any of the five conditions that promote explosions.
Explosions can also be prevented if control is maintained on all equipment and other things that can lead to increase in temperature, sparks or heat. Smoking has to be completely prohibited, the use of rubber soled shoes preferred so that there is less friction and thus heat, while all sources of heat and electrical equipment must be kept away from the dust environment.
One of the most efficient ways of preventing combustible dust explosions in workplaces is to ensure that any process producing dust takes place in spaces from which the air can be easily evacuated. Paint booths and similar booths for welding and other buffing and grinding processes that produce dust are quite common, and they make working safer, because they remove the combustible material as soon as it is produced. Extractor fans must be designed to extract the complete volume of air which contains combustible dust, within seconds of it being produced. It also becomes necessary to also ensure proper ventilation so that the extracted volume of air is again replaced. At times this may require the forced form of ventilation.
In many industries the combustible dust can contain material that is quite costly and needs to be retrieved. In such cases the extraction equipment is designed to pass through mechanical, liquid or chemical filters that will enable the material to be used again or even serve as valuable residue that has an economic value. Combustible dust fires and other hazards from combustible dust can be minimized if proper care is taken to address the various factors that lead to explosions.