HPS lights – They have exciting way in producing lighting by using sodium. Two varieties of lamps, and they are low pressure and high pressure. The lamps with low-pressure sodium are efficient electrical light sources highly but their applications of yellow light are restricted to outdoor lighting like street lamps They have a broader light spectrum when it comes to high-pressure sodium lamps but still poorer in color rendering than other lamp types. The lamps with low-pressure sodium do give yellow light in monochromatic only and at night so inhibit color vision. This is because of sodium-vapor lamps have ability in causing less light pollution than the lamps of mercury-vapor. Many cities with large astronomical observatories have been employing them.
High-pressure sodium AKA HPS lights have smaller element containments like mercury. They simply when first struck produce a dark pink glow which then when warmed, an intense pinkish orange light is produced. Some of the bulbs also produce a pure to bluish white light briefly if a high-pressure arc discharge achieved by the mercury. This is just before the sodium is warmed completely. The HPS lamp uses sodium D-line as the main source and the high pressure in the lamp does pressure broadening.
12 Photos Gallery of: Exciting HPS Lights
HPS lamps are energy efficient with only 100 lm/W when they are measured for photopic lighting conditions. They have been used for outdoor area lighting widely like security and streetlights.