Although tungsten has a high melting point, natural “blackening” occurs during the lifetime of a UV lamp, due to very high arc temperatures operating between each electrode. During normal operation, the electrodes start to erode, and the tungsten material starts to sputter depositing on the inside of the quartz body. When the transparency of the quartz body is compromised, UV output potential is significantly reduced.
All lamps will blacken at the ends eventually, although UV lamps used in disinfection systems should experience this more gradually as they tend to be operated continuously.
- Alpha-Purify lamps have a “special material” coating on the end of the electrode to prolong the life of the electrodes.
- This problem is usually avoided by not switching the UV lamp on and off, which avoids power cycling.