As discussed in a prior EmersonExchange365 post “Understanding Light Distribution Patterns for Industrial Locations”, directional LED lighting can be harnessed using effective optic design. Perhaps the greatest opportunity for this unique LED benefit lies in the luminaire reductions that can be achieved in catwalk lighting applications.
Traditionally, catwalk lighting was designed utilizing 70W high pressure sodium (HPS) lighting spaced at intervals of 15ft; typically stanchion mounted at a 25 degree angle, 8-10ft high. The determination of this spacing and mounting height was based on achieving the IES requirement of 5 foot-candles of illumination on a walkway in an industrial facility. Although these HPS luminaires produced over 5600 lumens of light, the omni-directional nature of the light source resulted in only about 72% of the light in downward illumination. The other 28% of the light was lost to side and up-light, not contributing to the needed 5 foot-candles of illumination. Below you can see a traditional catwalk shown both during the daytime and at night.
Today’s LED luminaires provide an opportunity to increase spacing in new industrial facilities, without compromising illumination, while improving light uniformity and of course, reducing energy usage and environmental impact. The most significant improvement is seen when utilizing Emerson’s Appleton Mercmaster LED Generation 3 Type I secondary optic.
IESNA Type I simulation Type I used in a walkway
The IESNA Type I optic provides a long narrow light distribution pattern, perfect for illuminating a walkway. Compare a typical HPS light spread, shown on the left below, the Type I light spread shown on the right. This light pattern perfectly fills a typical 3ft wide catwalk, without unneeded overspill, allowing us to provide illumination just where it is needed, thereby optimizing the efficiency of each luminaire.
As shown in the illustration, a 146% increase in luminaire spacing, to 37ft, provides enough illumination to achieve the required 5 foot-candles, with a uniformity improvement of 80% and a power savings of 68%. A diffused globe was used in this simulation which provides the maximum visual comfort for workers maneuvering on the catwalk. In a recent project, Emerson was able to reduce the customers' planned luminaire count by 10% utilizing these Type I optics. Additionally, cable costs were reduced by 10% and the reduction of load currents translated to fewer panelboards and lower overall engineering and installation costs.
For more information on Mercmaster Genertaion 3 LED secondary optics, check out our video “Appleton Mercmaster LED Generation 3 Luminaire Overview”, or visit us at www.materingledcom.
Ellen Helm | Manager, Appleton Lighting |Electrical & Lighting
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