How Do You Know If a Light is really Explosion Proof?|
Hazardous location lighting equipment is in the simplest explanation used in places where concentrations of volatile gases, flammable dust or particulates, or flammable chemicals are high enough to present a danger of ignition that can lead to explosion or fire. In a hazardous location, something as simple as a tiny spark can be enough to ignite flammable gases or dust and create a fire. In worst case scenarios, such a spark can lead to catastrophic explosions as an atmosphere in an enclosed space that is saturated with flammable gases or particulates is ignited. Since most normal electrical equipment has some potential to produce heat or sparks, it is critical that anything that relies on electrical power to operate in a hazardous location be designed to prevent the creation of these sparks or heat.
There is more than one way to achieve protection against unwanted heat and sparks and because of this some measures and standards regarding the effectiveness of these methods is necessary. This has led to the creation of tests designed to rate the effectiveness of equipment in preventing heat and sparks in hazardous locations that are administered by approved laboratories. These labs rate equipment according to established standards which allow them to rate and categorize equipment according to its effectiveness and suitability for use in various types of hazardous locations. These standards then can be used to apply approval ratings to equipment, allowing industries to know definitively that the explosion proof lighting equipment they are considering is safe to use in their applications as well as in conformance with the regulations set out by controlling governmental bodies such as OSHA.
Equipment that has passed testing by an approved laboratory is not truly “certified” by them although this is the term most commonly applied since it is the simplest and most easily understood. In reality, these testing bodies apply approval that states the lighting equipment in question has passed their tests and conformed to the standards for use in its rated category and division. Approvals are directly affixed to explosion proof equipment which clearly displays the units’ suitability for use in a particular type of hazardous area. Explosion proof lighting for instance will have a metal tag or plate affixed to the housing or body that will contain the necessary approval rating information. These tags contain the group and division ratings, class, and the name of the approving body. All electrical equipment used in hazardous locations must carry this tag or it will likely be in violation of applicable regional and national governing regulations.
Hazardous locations vary greatly in their threat and their composition. An area that frequently produces a great deal of combustible dust will not have the same volatile characteristics as an area that frequently contains the presence of petrochemical vapors. Because of this there are different categories of hazardous locations that are rated by Class, Division and Group. Generally speaking, the more potential there is for fire or explosion, the higher the ratings necessary, thus a Class 1 Division 1 rating like the one given to the Larson Electronics EPL-BS-70-100 Explosion Proof Light would signify some of the strictest standards while a Class2 Division 2 rating would signify somewhat less strict standards. In order to properly match explosion proof lighting to a hazardous location by its rating it is necessary to understand how hazardous locations are rated as well. For this, users must consult with regulating bodies such as OSHA and guidelines provided by publications such as the NEC to make a clear determination for their area.
It is also important to keep in mind that not all geographical regions or countries will have the same regulations. Equipment that is going to be used in the U.S. for example must carry approval from testing bodies that are certified by U.S. regulatory agencies such as OSHA. Although there has been some movement towards setting some international standardization of approvals, it remains necessary that equipment be checked to make sure it adheres to local regulations or it may not be adequate enough to satisfy both federal and local regulations as well as the conditions set out by insurers.
The bodies that apply approvals are generally established laboratories that have been accredited by federal institutions. In the U.S. for example there are several laboratories that have this accrediting, such as Underwriters Laboratories which is one of the most well known, as well as FM Approvals LLC, Intertek Testing Services NA, Inc, and National Technical Systems, Inc to name a few. These laboratories are generally accredited to handle certain testing and approval operations according to the various types of equipment and areas to be addressed. Overall, as long as a piece of equipment carries their approval and they are listed as accredited, the equipment can be assumed to be suitable and within conformity of the regulations for its intended type of hazardous location.
One common problem that must be watched out for involves the sometimes misleading labeling that takes place within the lighting industry. One of the more common problems encountered involves the selection of lighting equipment that is labeled as Vapor Proof for use in hazardous locations that in reality require an explosion proof rating and approval. The term Vapor Proof is misleading and does not infer the safety of an illumination device. While it may indeed be vapor proof, explosion proof lighting is in reality not rated by how well it is sealed against intrusion by flammable vapors, but by how well it resists producing accidental ignition which is something else entirely. This is an excellent example of why ratings and accredited approvals are so important and necessary. Without them, there would be no way to know for certain if a piece of equipment was in fact safe for use in a volatile environment. Certainly a sealed lamp may be vapor proof, but what if the lamps surface is capable of reaching extreme high temperatures? This then would mean that despite no vapor entering the lamp, ignition would still be possible, making the lamps vapor proof labeling entirely worthless in a hazardous location.
Suffice it to say, only use explosion proof lights that carry the displayed approvals from accredited laboratories and make certain they are used in their properly designated locations. Anything else is simply not worth the danger or the risk.