BOOM! Ugh
- Thread starter wade1
- Start date
Quite a bit actually, most was in tiny little fragments (it seems to have litererally gone off like a bomb inside). Its the second bulb in a week to get its contents dumped into the tank! But, a little glass doesn't mean much to me so I ignored it. Hopefully theres nothing toxic about the vaporized metals it uses.
Wade
Wade
vair":33bc8t05 said:
Yes. What happens is skin oils get on the bulb from your fingers. The bulb gets MUCH hotter under that oil an it begins to form a glass "bubble" and the pressure/heat pops out the glass.
Not sure this is what happened to you here but I know it will happen to high wattage halogens and the like. I remember in college when I ran film projectors for the student union....man those projecter bulbs would do this in a heartbeat if you didn't follow strict precautions when loading them in.
Yeah, you touched it.
What happens in metal-halide/quartz lamps, is the metal in the filament actually burns so hot it turns into a gas. When it cools, it attracts to the hottest part inside of the lamp.
When the lamp is running like it should be, (the outside glass clean) the hottest part is where the filament is the thinnest- where the most ions have 'boiled' off. They cool and reattatch to the thin spot, and re-inforce the weak spot in the filament.
When you touch the glass, the oil from your skin stays on the bulb. As the lamp heats up, so does the oil. The inside of the envelope (the glass of the bulb) where you touched gets hotter than the filament. The loose ions from the filament now attatch to the glass, rather than back to the filament. Sooner than later, either the glass cracks from the heat, or the filament gets too thin in a spot and burns out.
Either way, it's time to replace a bulb.
TO avoid this, you can either
A: never touch the bulb (almost impossible)
B: Cover the bulb with plastic of some kind, just remember to take it off, burning plastic stinks.
C: Just wipe the whole bulb down with rubbing alcohol after you install it.
Hope this helps.
B
What happens in metal-halide/quartz lamps, is the metal in the filament actually burns so hot it turns into a gas. When it cools, it attracts to the hottest part inside of the lamp.
When the lamp is running like it should be, (the outside glass clean) the hottest part is where the filament is the thinnest- where the most ions have 'boiled' off. They cool and reattatch to the thin spot, and re-inforce the weak spot in the filament.
When you touch the glass, the oil from your skin stays on the bulb. As the lamp heats up, so does the oil. The inside of the envelope (the glass of the bulb) where you touched gets hotter than the filament. The loose ions from the filament now attatch to the glass, rather than back to the filament. Sooner than later, either the glass cracks from the heat, or the filament gets too thin in a spot and burns out.
Either way, it's time to replace a bulb.
TO avoid this, you can either
A: never touch the bulb (almost impossible)
B: Cover the bulb with plastic of some kind, just remember to take it off, burning plastic stinks.
C: Just wipe the whole bulb down with rubbing alcohol after you install it.
Hope this helps.
B
It's pretty hard to touch the bulb when it is inside a glass enclosure like that. (the actual bulb is pretty much completely gone in that pic).
IME touching the outer glass envelope with your hands doesn't harm the bulb. Just looks like a freak incident to me.
FWIW, Nathan
IME touching the outer glass envelope with your hands doesn't harm the bulb. Just looks like a freak incident to me.
FWIW, Nathan
Actually, what npaden points out is correct (not the case in DE bulbs!) because the internal bulb exploded, sending shards and debris into the outter envelope and rupturing the outter envelope in the process... it blew a perfectly round hole through it.
Just a freak occurence, probably brought on by the age of the bulb.
Still not fun.
Wade
Just a freak occurence, probably brought on by the age of the bulb.
Still not fun.
Wade
Guys, it's the MH capsule that exploded, then blew out the outer envelope.
What happens with MH lamps is that the electrodes decay with use. Each time the lamp is struck, some metal jumps from one electrode to the other, and/or some of that metal ends up deposited inside the MH chamber.
Over time, this causes the lamp to draw more and more current and to run at a higher envelope temperature. If the ballast does not limit the current properly, an explosion can happen.
Pulse start ballasts are MUCH better at maintaining the electrodes in a MH lamp, as compared to the normal cap-and-coil ballasts. That's where the claims of increased lamp life when using E-ballasts come from.
HTH
James
What happens with MH lamps is that the electrodes decay with use. Each time the lamp is struck, some metal jumps from one electrode to the other, and/or some of that metal ends up deposited inside the MH chamber.
Over time, this causes the lamp to draw more and more current and to run at a higher envelope temperature. If the ballast does not limit the current properly, an explosion can happen.
Pulse start ballasts are MUCH better at maintaining the electrodes in a MH lamp, as compared to the normal cap-and-coil ballasts. That's where the claims of increased lamp life when using E-ballasts come from.
HTH
James
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