Low Pressure Sodium Lamps
They are discharge lamps in which the light is produced by radiation from sodium vapour.
Performance: The low pressure sodium lamp is the most efficient lamp available at present with efficacies up to 200 lm/W.
Applications: Because the radiation produced is monochromatic yellow, the use of this lamp is confined to locations which do not demand colour discrimination, typical applications would be road lighting.
Lifetime: 18 – 185 Watt
100 – 200 lm/W
12000 – 24000 hours