What is low pressure sodium lighting (LPS)? For starters, it’s a form of induction lighting that uses a low pressure sodium bulb and is actually a closer cousin to fluorescent and neon lamps than to high pressure sodium lighting. Low pressure sodium lamps were traditionally used for street lighting, tunnel lighting, and other industrial forms of lighting that did not require high color rendering index.
The poor color rendering index of low pressure sodium is illustrated in the image of the two Honda Fits to the right. One car is red, and one car is black, but underneath the low pressure sodium lighting, they both appear black.
LED Alternatives to Low Pressure Sodium Lamps
There are a few main problems with low pressure sodium lighting besides the poor color rendering index that must be addressed. Low pressure sodium bulbs are known for their warm yellow light and are commonly used in street lighting and tunnel lighting. The first and most obvious issue with low pressure sodium lighting is the fact that the leading manufacturer of LPS has announced that they will be discontinuing the product. Due to the fact that this company makes nearly all the LPS lamps in the world, LPS lamps will no longer be on the market and using LPS will no longer be possible in a few years once there is no more stock.
The rated life of low pressure sodium lamps is not as good as LED either, usually only having a life of about 18,000 service hours. Most LED fixtures are L70 rated at at least 50,000 hours, making them much more efficient than LPS. Not having to change lamps in difficult locations such as tall streetlights and in tunnels is a major advantage of LED lighting.
Third, this type of light source takes about two full minutes to reach full brightness levels, as demonstrated by the image to the right. The gases inside the lamp take a much longer time to react and ignite than LEDs, which are actually digital and powered by a driver, not by a combustion process. Like other induction lighting, LPS is flammable and also must be disposed of properly in order to prevent mercury poisoning.
Access Fixtures can make LED fixtures such as the EPTA, APTI, and APTA in 1700K which is the same color temperature as low pressure sodium, but with none of the drawbacks. These fixtures are perfect for areas where LPS would be, but they are safer, more flexible in design and optics, and longer lasting. Contact an Access Fixtures lighting specialist to order your EPTA or APTA fixtures in LPS color match (1700K).
