low pressure sodium lamp

1.The light efficiency of low pressure sodium lamp is very high and between 150LM to 210LM. However, that of the high pressure sodium lamp is just between 100LM to 150LM. 2.Low pressure sodium lamp is a kind of low-pressure gas discharge lamp (glow discharge). High pressure sodium lamp is a kind of high-pressure gas discharge lamp (arc discharge). 3.The construction of low pressure sodium lamp is big so its power is small and ranges from several watts up to more than one hundred watts. The construction of high pressure sodium lamp is compact so the power can be very high. The general lighting can be between 35W to 1000W. 4.The low pressure sodium lamp uses cell-shell made of sodium resistant glass and the high pressure sodium lamp uses electric arc tube cell-shell made of polycrystal alumina. 5.The low pressure sodium lamp has bad color rendering so everything looks like yellow color and can not recognize the original colors.