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Sodium lamp series

Sodium, like mercury, can also be used as the luminous vapor in the discharge tube. However, its vapor pressure, ionization potential and excitation potential are all low, so the design is very different from that of mercury lamps. Ionized sodium also has a strong chemical reaction ability, which raises acute problems in the selection of materials. These problems of high-pressure sodium lamps have only been solved in recent years.

The characteristics of low-pressure sodium lamps are: nearly monochromatic radiation, large volume, and high luminous efficiency (can exceed 150 lumens/watt). Therefore, it is a very economical light source in occasions where the requirement for color discrimination is not very important, especially in street lighting, where only visibility is required.

The color rendering of sodium vapor discharge is greatly improved at higher vapor pressures, and the luminous efficiency of high-pressure sodium lamps above 250 watts can exceed 100 lumens/watt. This lamp is roughly the same size as a high-pressure mercury lamp and can be used for street lighting and large-area floodlighting. It can also be used for indoor lighting where color rendering is not required.

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