T3D Re: projection lamps ALSO SOME TIPS

[john bercovitz <bercov@xxxxxxxxxxx>]

> Question: If you are not supposed to run air over a lamp, then why do
> manufacturers (Many, All or Most?) incorporate a blower of some kind.

The question in my mind is, "Why not run the blower when the lamp is 
hot but is off?"  George says it might be because of differential 
contraction.  I think quartz has a pretty low coefficient of expansion 
but it does operate at a very high temperature.  I think if you are not 
supposed to cool the lamp with the blower when the lamp is off, then the 
reason the blower can be turned on is so that you can cool a burned out 
lamp quickly so you can get the show going again quickly.  

John B


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