MH-DE nomenclature

[T Man]

I recently replaced my three MH-DE 150W/10K with 20K's. One of the bulbs has a pile of ash inside and what looks to be some type of sensor with the center gone. The bulbs have served me well, my question is what is that paddle shaped object with a wire fixed to the glass? A sensor or indicator of sorts or maybe even an ignitor? Here is a photo of two of the old bulbs side by side for comparison. Any feedback would be appreciated, Thanks. TinMan

 

[PaulErik]

That is a getter. It is used to absorb impurities such as hydrogen, vapors and hydrocarbons inside the outer bulb.

Cleaner the atmosphere is longer the arc tube/lamp will last. At high operating temperatures some impurities can diffuse into the quartz arc tube and alter the performance of the lamp.

From the picture it looks like the getter failed from to much heat or just got exhausted.

 

[T Man]

Thanks PaulErik, I understand how it works now. I would hope that the failure was due to exhaustion- I don't even want to think about heat issues. Anyhow it was time to replace the older bulbs, I have been thinking about the 20K's for some time now- I can honestly say that the colors in my tank seem to pop out even more under the bluer light. Thanks again. TinMan