IC-MAYJUN23-PG12+13_Layout 1 24/04/2023 10:34 Page 13
EXPLOSION SAFETY
Knowing the properties of your dust is paramount. Three main parameters should be tested; the first being Pmax, or the maximum pressure that can be reached on the basis of particle size. Next is the speed with which the pressure rise occurs, bearing in mind that this will vary according to room or vessel volume. Multiplying that pressure rise by the volume provides the Kst, which enables us to standardize how fast the pressure rises and define four risk categories: from St0 (does not explode) to St3 (very strong explosion). It should be noted, however, that a weaker St1 explosion is no less dangerous than an St3 event.
The final main parameter concerns knowing the minimum required ignition energy, which will enable safer handling. Other parameters include glowing temperature, whether the dust is conductive, and whether self-ignition is possible. All of these factors are very specific to a particular dust generated in a particular process, so seeking professional advice is always recommended.
PLANNING FOR SAFETY
Once you have determined the combustibility of your dust, you can develop a plan to mitigate the risks in your process. First, although good housekeeping is only a partial solution, audit your process to identify where nuisance dust is generated, released, or accumulates – and deal with it. These often include intake and mixing locations, bag dumps, welding or cutting
stations, beams, and light fixtures. In each location, analyze the production processes, housekeeping practices, dust control measures, and potential ignition sources present. Bear in mind that when dust builds up in several locations, a flame front can create a pressure wave that leads to a chain reaction, dislodging and feeding on more dust as it moves through the building – as happened during the notorious Imperial Sugar plant explosion that killed 14 people. Also, a supposedly empty vessel is usually more dangerous than a full vessel – so, for example, opening an inspection hatch on a silo may cause lingering deposits on ledges to become airborne and increase risk.
Even the equipment employed to mitigate the problem can be a danger zone, with dust
collectors being responsible for 30 per cent of such explosions. Cleaning the filter media or emptying dust bins can also create locally dangerous dust clouds.
Many standards and codes may influence decisions on dust control, including local, state, and European regulations. Knowing the regulations that apply to your facility is critical, and process owners should always research the regulatory requirements in their area. As of July 2003, there are two directives issued by the European Union that are related to the protection of employees and equipment from risks related to potentially explosive atmospheres 1999/92/EC and 2014/34/EU (ATEX Directives). ATEX directives make it clear that the responsibility for evaluating the risks and creating an explosion protection document lies with the employer/process owner. Process owners are responsible for the selection of their combustible material management strategy and to assure compliance with all applicable codes and standards. Having decades-long experience in providing
high-quality dust collectors that have become an integral part of many plants’ combustible dust mitigation strategies, Donaldson can help review process owners’ mitigation strategies and provide the optimal dust collection solution for their chosen strategy.
Donaldson Company
www.donaldson.com
INDUSTRIAL COMPLIANCE | MAY/JUNE 2023 13
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46
