Illustrated here is an unusual Russian low pressure sodium lamp, manufactured by MELZ in 1966. The discharge tube has a U-shape, and it is assembled within an outer vacuum flask. Normally on European lamps it is possible to remove the discharge tube and replace that while re-using the outer vacuum flask, but on this Russian lamp it has been assembled with a powerful spring which is almost impossible to remove. Clearly it was the intention to replace the whole lamp when the discharge tube failed.
