L.J. Star Inc., a  supplier of sight glass lighting, has released a new white paper that discusses the results of a study used to determine which color temperature of white light is best suited for illuminating the interior of stainless steel process vessels. A good view is essential for observing the characteristics of the process medium and for verifying process steps such as clean-in-place. 

The study examined the color absorption and reflection of cool and warm white light by stainless steel. During the test, a warm white LED and a cool white LED were placed at a sight port on a stainless steel tank, and the luminosity of each LED was measured at a second port using a foot candle light meter. 

It is common to use a sight port for the light inlet and another sight port for viewing—with both ports located on top of the vessel. (Viewing ports with integrated sight glass lights are also available.) In this study, the two extreme ends of the spectrum (warm white and cool white light) were tested to demonstrate the effect of color frequency on absorption and reflection. Measurements revealed that the cool white LED was more efficient at illuminating the tank than the warm white LED. 

The test configuration incorporated Metaglas®, the strongest and safest fused sight window in the industry. In addition to Metaglas, L.J. Star offers a variety of sight glass lights, including LED, halogen, and fiber optic lights in ex- (explosion proof) and non-ex versions. L.J. Star’s new LumiStar3000™ is the world’s brightest sight glass light, allowing an unprecedented view of processes, even in large tanks.