Discussion | Are there any ignition sources you don’t know about?

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Discussion | Are there any ignition sources you don’t know about? The three elements of combustion: Combustion requires three conditions: 1) a combustible material, 2) an oxidizing agent that facilitates combustion, with oxygen in air being the most typical example, and 3) a ignition source with sufficient energy. These three elements constitute the requirements for combustion. The five elements of explosion: Two additional conditions are needed on top of the three elements of combustion to enable an explosion: 4) a confined space, and 5) adequate mixing or dispersion (dust can explode only when it is suspended in the air). Together, these constitute the five elements of explosion. Ignition sources: \"In the chemical industry, ignition sources are the only things that are available everywhere.\" Whenever dealing with flammable liquids, gases, dusts, or their mixtures, ignition sources are always present. The consequences of a fire can be catastrophic – they may lead to casualties, environmental damage, negative public sentiment, a decline in business operations, and potential reputational loss. In our professional assessment of ignition sources, 13 types are taken into consideration. The following are the ignition sources listed according to EN1127-1: 1. Mechanical sparks 2. Self-heating (including self-igniting dust) and other exothermic reactions 3. Hot surfaces – including heat generated by friction 4. Electrostatic discharge 5. Flames and hot gases 6. Electrical equipment 7. Stray currents and cathodic protection 8. Lightning 9. Radioelectromagnetic radiation, 104 Hz to 3 x 1012 Hz 10. Visible light electromagnetic radiation, 104 Hz to 3 x 1012 Hz 11. Ionizing electromagnetic radiation 12. Adiabatic compression and vibration waves 13. Ultrasonic waves. In addition to these, there is another type of ignition source, namely “hot work,” which is not listed separately (as it encompasses aspects of several of the above types, such as electrical equipment, hot gases, flames, and hot surfaces, which is worth noting). There are many examples of ignition sources related to fires and explosions; numerous such examples can be found in Lee’s work on the identification, evaluation, and control of industrial hazards in loss prevention processes. The table below is based on its third edition. Examples of ignition sources: Flames, sparks: Sparks from heights or the ground ； Large flames or small flares ； Incineration device. Furnace: Natural or forced air flow. Combustion heater. Boiler. Laboratory heater: Bunsen burner ； Furnace. Personal space heaters: solid fuel or electric ignition heaters. Combustion operation: Burning waste ； Burned during the demolition process. Ignition: Remove the detonator; others **. Flash warning: Hazard alert flash ； Fog warning*. Accidental fire. Hot materials: soldering iron; hot particles. Hot work – Welding: Arc welding ； Acetylene oxygen welding. Cutting: Acetylene-oxygen cutting. Grinding processing. Drilling a heating vent hole. Hot surfaces typically include: containers and pipes. Mechanical: Engine ； turbine ； Exhaust gas. Laboratory equipment: hot plate ； Oven. Hot particles: smoke and dust. Friction and impact Impact: hand tools, power tools, guide studs, loosening of compacted materials, moving vehicles. Friction: slippage of belts, conveyor belts, idlers, brakes, clutches in mechanical systems, as well as in road tankers or rail tankers. Heat materials/gas-releasing materials: hot ash generated from boilers; used catalysts ； Thermally processed materials. Hot steam. Reactive and unstable substances; self-igniting materials. Incompatible materials: Materials that can react with building materials. Engine fuel: gasoline, diesel, or a mixture of gasoline and diesel engines. Friction and collision: thermite reaction. Equipment: Catalytic element. Mechanical fracture is accompanied by spark release caused by the fracture. Atmospheric interference causes lightning strikes. Compressed gas mixture power: compressors, high-speed blowers. Smoking: Ways to light it: matches, lighters. Smoking items: cigarettes, cigars, pipes. Motor vehicles: General motor vehicles: gasoline, diesel, or electric-powered. Lifting machinery: forklifts, aircraft. Electrical machinery: motors, alternators, generators, converters. Fixed equipment: Contact devices such as switches, relays, and contactors. Insulator: Arc in the spark gap of high-voltage insulators. Cables: cracked cables, damaged cables, water intrusion. Battery: Connection of a damaged battery. Heating strip. Lighting fixtures. Fault current: poor connection. Portable devices: watches, radios, visual systems, cameras, hearing aids. Crustal movement: Sparks caused by crustal movements such as earthquakes or subsidence of strata. Despite the introduction of European regulations for use in explosive environments, such as the ATEX directive, as well as regulations like DSEAR** in the UK which includes both ATEX and chemical additives directives, experts still find inadequate control of ignition sources in many places. There are many such examples, including: 1. Improper bonding and grounding of equipment and personnel; 2. Lack of maintenance of the grounding system; 3. Lack of understanding regarding how to handle flammable liquids with high non-conductivity safely (such as toluene); 4. Using plastic bags to add powder to solvents; 5. Failing to select the appropriate flexible intermediate bulk container (FIBC) in accordance with static electricity control requirements; 6. Failure to apply maintenance practices in areas where non-electrical equipment is used in hazardous (explosion-proof) environments; 7. Inadequate control of hot work, including a lack of understanding of what constitutes hot work; 8. Poor maintenance of “explosion-proof” electrical equipment, along with incorrect use or installation; 9. Lack of data on safe drying and storage temperatures for dust; 10. Lack of understanding of the combustion characteristics of combustible dusts; 11. Lack of awareness regarding the impact of mixtures on flammability; 12. Poor change management resulting from insufficient technical knowledge within companies. Among these examples of inadequate control of ignition sources, some are due to a lack of awareness, while others reflect the complexity of the issue. Guidance documents do exist, but they are difficult to understand, and even more so to apply in practice. Myths about ignition sources It is impossible to cover all the knowledge related to ignition sources in this article; however, the focus is on discussing the things that plant personnel truly need to know. The following are some general misconceptions regarding process safety, particularly those related to ignition sources. Eliminating ignition sources is generally not recommended as the ‘only’ basis for safety. However, when protection systems such as inerting or explosion venting are also available, it is quite important to minimize the need for these systems as well. Myth: Viewpoint 1 – For 30 years, I have been feeding powder into the reactor through open hatches, and there have never been any explosions; therefore, I shouldn’t have any problems with ignition. Viewpoint 2: My operating procedures keep me below the liquid’s flash point, which ensures my safety. Thirdly, we can use literature as a reference for our dust-proof ignition performance, with no change in the materials. Viewpoint 4: We don’t have a problem with ignition, because we used a hot work permit. Viewpoint 5: My operators do not generate static electricity ； They did not experience friction. Viewpoint 6: Everything is grounded, so there is no issue with static electricity. Viewpoint 7: We keep all pipe joints bonded. Viewpoint 8: We use a barrel with a grounding clip, so we are safe. Viewpoint 9: I don’t have any isolated conductors in my factory; their metals are in contact with each other, so they must be grounded – right? Viewpoint 10: We use anti-static shoes, so there are no spark issues with our personnel or the tools we use; I don’t think we will ignite flammable vapors. Summary: Despite the existence of appropriate explosion protection systems, it remains important to reduce the demands placed on these systems. Protection systems such as explosion venting are not used frequently – therefore, it is particularly important to control ignition sources in areas where flammable gases are present. It has extensive experience in managing the risks of fires and explosions caused by combustible gases and vapors, as well as combustible dusts. For a company to operate at an acceptable level of risk, it is necessary to have an understanding of the specific hazards associated with these materials.