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05/09/08 |
The Right Explosion Proof Light Can Save Your Life
Along the lines of The Colbert Reports’ Better Know a District, Larson Electronics is using www.magnalight.com to help their customers Better Know a Light. In this new series, Larson Electronics explores the latest advances in lighting technology, demystifies varies acronyms and terms and helps prospective customers make the best choices on lights. Although Stephen Colbert’s approach to unnerving various district’s representative in a fun and witty way, the Better Know a Light series is more informative and less humorous.
In this edition of Better Know a Light, we explore intrinsically safe lights and explosion proof lights. While term intrinsically safe is often used to characterize explosion proof lights, this term applies to a very narrow choice of lights. Intrinsically safe lights are defined as lights that create no heat, no spark and do not produce static electricity when dragged. Most spotlights and flood lights produce heat and some kind of spark, thus most lights are no intrinsically safe. Some specialty lighting products based on fiber optics are coming to market shortly that will meet these ultra-safe specifications.
Explosion proof lights are generally what customers need when searching for intrinsically safe lights. Explosion proof lights differ from hazardous area lights and are defined by the types of conditions their safety rating applies to. Class 1, Division 1 lights are the safest lights, meaning that they can be used in confined areas with exposure to flammable vapors and gases. The petrochemical and marine industries usually require Class 1, Division 1 lights to inspect and clean tanks, clean fuel cells, turn around facilities, etc.
Class 1, Division 2 lights are considered hazardous area lights, which generally means environments laden with pulverized dust, solvents and fumes. Class 1, Division 2 lights are required in grain silos, barges, sugar processing plants, paper mills, coal processing plants and grain silos where flash fires are a significant risk. The February 2008 explosion that incinerated an Imperial Sugar refinery, killing 6 people, in Georgia was the result of an ignition of sugar dust in a silo where refined sugar was stored before being packaged likely ignited like gunpowder. “The result was as devastating as a bomb. Floors inside the plant collapsed, flames spread throughout the refinery, metal girders buckled into twisted heaps and shredded sheet metal littered the wreckage. ‘There was fire all over the building,’ said Nakishya Hill, a machine operator who escaped from the third floor of the refinery uninjured but for blisters on her elbow.”
Safety ratings are based on several factors and generally the rating includes a group designation. Groups A,B,C,D are gas vapor related, including acetylene, hydrogen, benzene, hexane, naptha, acetone, benzol, lacquer solvents, etc. Groups D,E and F are specific to different types of dust. In general, Class 1, Div 1 are usually tested and rated for groups A-D. Given that is a more rigorous safety rating, it is assumed that Class 1, Div 1 will be sufficient for Class 1, Div 2 rated environments.
Finally, lights are assigned a t-rating which indicates that temperature at the lens. In order to receive a Class 1, Division 1 rating, the temperature at the lens must be below the ignition point of the gases and/or dusts it is rated for. This is why you won’t see anything stronger than 400 watts on an explosion proof light assembly. Beyond 400 watts, metal halide lights generate too much heat, raising their t-rating past the safe point.
The testing and certification of explosion proof lights is conducted within a lab environment. A chamber is filled with propane and the light is activated inside the chamber. If the light ignites the propane, then it fails the test. Secondly, the light itself is filled with propane and various variables are introduced to cause the light to explode. Combinations of tests similar to these are conducted in a controlled environment to determine the appropriate safety rating.
Larson Electronics offers a growing range of explosion proof lighting at www.magnalight.com which offers cart style tank lights, pedestal style lights, boom style lights, string lights, hand lamps and the only Class 1, Division 1 High Intensity Discharge (HID) flashlight with lithium ion battery. In addition, Larson Electronics can build to specification any explosion proof lights and/or hazardous area lights for their customers. Please visit www.magnalight.com or call 1-800-369-6671 to learn more. |
