High Pressure Sodium Lamps

High-pressure sodium vapor lamps are a variant of low-pressure lamps with the aim of improving color rendering at the expense of luminous efficiency.

The discharge tube consists of sintered aluminum oxide containing a mixture of rare gases (xenon and argon or neon and argon). A vacuum is made between the discharge bulb and the outer bulb.

The luminous efficiency is between 80-130 Im/W while the color temperature ranges from 2000 to 2500 K. Color rendering is very low with an approximate value of Ra 20-30.

High-pressure sodium lamps can have E27 or E40 socket with tubular and ellipsoidal dusted shape for better light diffusion.

They have excellent luminous efficiency and operate with external ballast and ignitor. Their lifetime characteristics ( up to 24,000 hours ) and very low maintenance make them particularly suitable for commercial and industrial lighting in public and urban areas.

They are also known by the abbreviation " sap lamps ".