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Re: halogen bulbs



On Thu, 9 Apr 1998, David Dockstader wrote:
For those of you who know about light bulbs, what's the deal with halogen?
I can see why a Xenon filled bulb would be good but halogen?

I asked the same question a few months back and was told the following...

When a filament gets as hot as those in high intensity bulbs, some of the
metal from the filament vaporizes into the bulb. The halogens react with
these vaporized particles from the filament and redeposits them back on
the filament. This extends the life of the bulb.

I have an Eiki video projector and the manufacturer recommends that once
the unit it turned on, it should be left running for at least 20 minutes
so that the bulb reaches its maximum operating temperature before you
turn it off. I was told that if you do not do this the life of the bulb
will be significantly reduced. I follow this rule and haven't lost a bulb
in 3 years.

I hope someone knows the chemistry behind this process. I would like to
know some of the chemistry behind this process.