Avoiding the risk of fire or explosion is a major safety concern in any environment where flammable or combustible materials are present. Most manufacturers, processors, and other industrial organizations recognize the importance of hazardous area safety and have established programs and procedures to identify potential risks and reinforce safe behaviors.
Knowledge of Occupational Safety and Health Administration regulations and educating workers in all aspects of safety management is critical to reaping the benefits and rewards of having an accident-free workplace. According to OSHA, providing a safe place to work not only results in cost savings by lowering or avoiding accident-related expenses, it significantly improves productivity and financial performance.
On the other hand, the consequences of not taking the proper precautions can be disastrous. Examples include the August 2012 Chevron refinery fire in Richmond, Calif., where a fire caused by flammable vapor hospitalized 20 employees and contaminated the air with tons of harmful pollutants, and the Imperial Sugar fire in Sugar Land, Texas, where an inferno caused by combustible dust caused 14 deaths and severely injured many others.
In addition to the human suffering, these tragedies severely tarnished the reputation of these companies and resulted in lengthy and costly investigations and stiff monetary penalties.
Regulatory bodies have established systems that classify locations based on their potential for dangerous conditions to exist. In fact, a substantial portion of the National Electrical Code (NEC) is devoted to managing hazardous locations, which is organized into different classes. Areas in which flammable gases or vapors are or may be present in the air in concentrations sufficient to explode or flame if an electrical or other ignition source is present are referred to as Class I hazardous locations.
All of us have been to a commonly found Class I spot: the pumps at your local gas station. A few industrial examples of Class I areas include oil refineries, chemical processing plants, cleaning and dyeing plants that use flammable liquids, and spray finishing booths.
Class II locations are defined as potentially hazardous due to the presence of combustible dust. Finely pulverized material, collected on flat surfaces or suspended in the atmosphere, can cause powerful explosions if ignited. Examples of Class II locations include, grain elevators, flour mills, powder processing plants, coal preparation plants, and saw mills.
The NEC further subdivides the Class designations based on the likelihood that an explosion will occur. In locations identified as Division 1, the occurrence of a fire or explosion is more likely because the flammable or combustible substance is present in everyday operations, during repair and maintenance, or is released by equipment breakdown. Division 2 areas are defined as those where the hazardous material would only be present under abnormal conditions, such as if a normally closed storage container began to leak.
When designing, organizing, and outfitting a Class I, Division 1, or Class II, Division 1 designated area, where the atmosphere is expected to contain a potentially flammable or explosive mixture of gases, vapors, or combustible particulates during everyday working operations, a good plant operator will manage the hazards through a comprehensive program that integrates the proper technologies with best operational practices.
Dust collection and ventilation systems that facilitate removal of vapors, fumes, and particulate are a must. Locating relief valves away from areas where dust might collect is an effective method for minimizing the risk of hazard, as is using filters to minimize the escape of dust and vapor from process equipment. Utilizing surfaces that minimize dust accumulation and keeping all areas easily accessible for cleaning are design criteria that should be kept in mind.
Due diligence must be also observed to ensure that all equipment and machinery used in these areas are explosion-proof and not potential sources for ignition. This includes equipment used during production as well as maintenance and upkeep of the production area.
The NEC defines criteria that must be met by equipment used in hazardous areas. To be certified explosion-proof for use in a Class I area, the housings must be strong enough to contain an explosion and eliminate the possibility of explosive gases or vapors escaping into the surrounding environment. In order to be used in Class II environments, equipment must be dust ignition-proof, or sealed against the intrusion of dust so that no internal explosion can take place.
In both cases, the equipment must operate at a temperature below the ignition temperature of the surrounding atmosphere and not generate any arcs, sparks, or flashes that could ignite flammable or combustible materials.
OSHA recommends, and in many cases requires, that certified explosion-proof or dust ignition-proof equipment be utilized for maintenance in hazardous areas, and cleaning with a high-performance, certified vacuum serves two purposes. By using vacuums constructed from non-sparking materials and ignition-proof components, you not only achieve a high level of operational safety, you eliminate dust as a potential source of explosion.
Regular inspections and vacuuming at specified intervals, as defined by a documented housekeeping plan, are essential and effective means for maintaining a safe workplace. Continually removing dust and debris that has collected on floors, machinery, walls, as well as overhead ducting, pipes, and conduit, will keep your hazardous area clean and clear to safeguard your employees from dangerous fires or explosions.
Modern technology is making it easier to prevent disasters before they happen. Facilities that handle hazardous materials should seek the best industrial vacuum option to meet their requirements. It is critical to purchase one that has been certified by a nationally recognized testing agency, such as Underwriters Laboratory (UL), for use in the class of hazard at your location. This will ensure that all components, both inside and out, are constructed from sturdy and non-sparking materials and the unit will not overheat.
Another critical feature of a hazardous area industrial vacuum system, especially one used to collect combustible material such as coal dust, is its filtration system. The best vacuums will have a multi-stage filter system capable of trapping minute particulate and prevent it from being exhausted back into the ambient air. A HEPA filter is an efficient option for filtering fine dust down to 0.3 microns, and ULPA filters are available for collecting even smaller particles — as fine as 0.12 microns.
A few other things should be taken into account when selecting a hazardous area vacuum system. In some environments, where electricity is unavailable or its use is undesirable, pneumatic vacuum cleaners are the best alternative, but be careful to choose one that is certified to not just collect hazardous materials but certified to operate in a hazardous environment. Also, if you handle flammable or explosive chemicals, an explosion-proof wet model is an excellent alternative, in either an electric or air-operated version.
The return on investment in workplace safety is immeasurable — it just makes good business sense to protect your people and your integrity. By safeguarding your workers and the surrounding community, you will enhance your company reputation and gain a competitive business advantage.
Tom DeMarco is president of DeMarco Industrial Vacuum Corp., a manufacturer of portable and stationary industrial vacuums, based in Cary, Ill. DeMarco Industrial Vacuum also makes material separators and custom-engineered vacuum systems. For more information, visit www.demarcovacuums.com.