low-pressure sodium lamp
A low-pressure sodium lamp is a type of lamp that produces light from sodium gas contained in a bulb operating
at a partial pressure of 0.13 to 1.3 pascal. Low-pressure sodium lamps provide
lighting compared to high-intensity
discharge lighting, but they have a very low color
rendition index. Typical applications include highway and security lighting,
where color isn't important.
Low-pressure sodium lamps work somewhat like fluorescent
lamps. Like high-intensity discharge lighting, low-pressure sodium lamps
require up to ten minutes to start and have to cool before they can restart.
Therefore, they are most suitable for applications where they stay on for
hours at a time. They are not suitable for use with motion detectors.
You can use the chart below to compare low-pressure sodium lamps with high-intensity
discharge lamps. If you don't already, it helps to understand basic lighting
principles and terms before making comparisons.
|Color rendition index (CRI)
||50 (poor to fair)
||3200–7000 (warm to cold)
||-44 (very poor)