Explosion-Proof and Dusting Equipment
Explosion-proof and dedusting equipment helps keep your operations safe by minimizing risk of combustible dust or hybrid (vapor and dust) applications explosions. Navigate frequently updated Recommendations and Standards to get the best protection for your process.
Your inspector will take a close look at the housing, hopper, and inlet or outlet ducting of your dust collector. A number of active and passive solutions can reduce the impact of an explosion.
Venting
When a dust explosion happens, the deflagration creates a high level of pressure that needs to be vented. Without venting, the pressure can overpressurize equipment and cause major Explosion-proof anddedusting equipment damage, and it can also transfer from one piece of equipment to other pieces connected by pipes or by a conveyor system. Explosion vents, when properly sized, prevent this from happening.
Explosion vents are typically ducted to atmosphere through short lengths of purpose-built ducting. The ducting is usually located outside, ideally well away from buildings or other plant areas where people might be in close proximity. This prevents the fireball that is ejected by the vent from causing further damage in a crowded area.
Vents are designed to rupture at a specific pressure to release the fire, heat and pressure from inside the vessel. They are tested and approved for their performance under specific conditions to make sure they will rupture at the required pressure and are designed, installed and maintained with care in accordance with national safety standards.
A newer type of explosion vent uses a compound dome that is less sensitive to the framing on which it is mounted. This solves a problem that has plagued older vents where accumulated dust and debris can increase their mass, and thereby reduce the amount of time it takes for them to open.
Suppression
While preventative measures are the primary method of preventing dust explosions it is not always possible to avoid an explosion occurring. In these cases, suppression is necessary to protect workers and equipment from the damaging effects of a full-blown explosion. Explosion detection devices recognize the warning signs of an impending explosion and alert the control system which then activates the suppression systems. The explosion isolation systems use either a chemical barrier or an explosion insolation valve to isolate the source of ignition.
The explosion suppression systems utilize a combination of sensors, a control panel and cylinders filled with the suppression agent which are rapidly injected into the protected vessel to neutralize the explosion. The rapid response of Explosion-proof anddedusting equipment manufacturer these explosion suppression systems helps to reduce damage to equipment and structures by quickly containing the explosion.
These explosion suppression systems also help to prevent the spread of an explosion from one piece of equipment to another. Explosion isolation systems accomplish this through chemical barriers or mechanical isolation valves that act fast to stop the flame and smother it, protecting other equipment from fire and explosion. All of these protection systems work together to create a safer working environment for your employees and protect your valuable assets from damage in the event of a dust explosion. Explosion-proof and dedusting equipment that is properly installed and maintained will provide your facility with peace of mind and the knowledge that you are operating according to the highest industry standards.
Isolation
If an ember or spark ignites combustible dust inside a dust collector, the explosion can propagate to other equipment, pipes and conveyors. Explosion isolation systems cut off the path of travel to prevent this by physically closing channels, pipelines or transfers acting as routes used by an explosion to spread.
Isolation systems are either chemical or mechanical in nature and can be triggered via pressure, optical flame or spark detection. When triggered, they quickly discharge suppression agent into ducts or conveyors to create a heat-absorbing chemical barrier to isolate the explosion and prevent flame propagation into connected vessels. They also offer flexible mounting orientations and can be field rechargeable to ensure rapid reset after an event.
Alternatively, mechanical isolation systems are designed to trigger the release of a high-speed knife valve. This high-speed valve acts as a physical barrier to smother the flame front and stop it from spreading to adjacent equipment. It’s a cost-effective method that works well in conjunction with venting systems. Both chemical and mechanical isolation systems are available in a wide range of sizes to suit most ducts, pipes or conveyors. They are also suitable for use with screw, belt or chain conveyors and bucket elevator legs. Each isolation system is custom-designed to mitigate the specific hazard, equipment to be protected, interconnections and operating conditions.
Monitoring
In addition to venting and isolation, another important method for preventing dust explosions is monitoring. Regular sample testing of the combustible dust can identify potential ignition sources, including electrical equipment and static electricity. Detailed records help workers understand test results and ensure the utmost transparency in case authorities or insurers conduct inspections. Detailed records also serve as reference material during training and can support continuous improvement efforts in the handling of dust.
Fugitive dust particles are a major hazard to plant and worker safety. These dust particles escape from processing and conveying equipment, settling on surfaces. Fugitive dust particles can ignite and explode when disturbed, causing secondary explosions that cause catastrophic damage and loss of life.
To avoid these devastating accidents, employers must develop a comprehensive plan for prevention and protection of combustible dust hazards. A basic step is to ensure that equipment is protected with enclosures designed to contain the flames and gases caused by a dust explosion. This can be achieved using intrinsically safe equipment, which cuts off thermal and electrical energy as soon as the device is exposed to a hazardous environment. Intrinsically safe devices use simplified circuitry, controlled internal temperatures and high dust resistance to prevent accidental combustion. Another method of protection is to replace the air in an enclosure with inert gas, which makes flame propagation impossible.