[TheForge] We'll leave the light on for ya...was rod ovens

Mon Mar 4 13:20:01 2002

Ahh, but we're not done with you yet. =20
The down side of using 130 W bulbs is that you get even LESS light for the =
power you use.  A better solution has been known for years and has been =
available retail for about 10 years =AF the halogen lamp.  It seems that =
if you put a halogen (e.g., iodine) into a light bulb, the tungsten vapors =
from the filiment react with the halogen vapors, resulting in a compound =
that does not deposit on the glass.  Instead it eventually hits the hot =
filiment and reacts to deposit tungsten metal.  Hence the halogen bulb is =
self-healing, to an extent.  Because of that, they can be run even hotter, =
so produce more light than a standard tungsten bulb.  But of course that =
makes the filiments even more delicate, so you have to be careful with =
them.  And since they're housed in quartz (to stand the heat cycles) they =
are subject to breakage if handled wrong.  (Apparently water weakens =
quartz, but I'm unclear on the chemistry.) =20

Meanwhile, fluorescent lamps work on a completely different principal.  An =
arc is struck down the length of a partially evacuated tube (containing a =
little nitrogen).  Just like in arc welding, the arc releases a lot of UV =
light, and comparatively little heat and visible light (that's compared to =
a hot filiment).  (If it were neon, not nitrogen, you'd get the famous =
"neon" red light.  But neon is at least 200X more expensive than nitrogen, =
and who wants red light anyway?)  Now, if you use a glass tube you'll lose =
most of the UV light and most of the energy efficiency.  But coat the =
inside wall of that glass tube with (highly toxic!) fluorescent compounds, =
and most of the UV light is converted to visible light.  There is a color =
difference, however, since the fluorescent compounds emit only a number of =
wavelengths, not a continuous spectrum.  Nonetheless, fluorescent lamps =
give you much greater energy efficiency.  (And if they won't light on cold =
mornings, wave a lit propane torch about 4 feet under them to warm the =
tubes a bit =AF then they'll light and stay lit.)

Bruce
NJ

>>> "Stephen McGehee" <[email protected]> 03/04/02 12:00PM >>>
Some light bulb basics here folks:
A regular incandescent bulb puts out appx. 97% heat and 3% visible
light.  If you look at the end of the bulb at the words and numbers, you
will notice it says maybe 60 Watt  120 Volts.  You probably bought the
bulbs at the supermarket or wally world, so I know that you have 120
Volt bulbs.  The filament, which is the working part inside, is just a
piece of wire.  Every time you turn it on the inrush current physically
whips that little wire a bit.  As that little wire sits there, glowing,
it is evaporating tungsten molecules into the atmosphere of the bulb.
That causes the dark deposit inside of light bulbs and vacuum tubes.
Over time, this evaporation makes for a thinner wire, and each time it
is turned on, that micro-movement whips it a little harder as it has
less mass.

But there is hope for the working class

and that rhymes...Go to a real electrical wholesaler(or to a lesser
degree, some place like Lowes or Home Despot) walk up to the counter and
ask for "130 Volt Bulbs"  They are available in most popular wattages
for about half again more than el cheapo discount center bulbs.  You are
buying a bulb with a heavier filament, and since the line voltage in
most parts of the country runs a bit over 120, these bulbs will last
many months longer than "regular" 120 Volt ones.   Another factor
contributing to bulb life:  The "life" of a given bulb is determined by
burning a big mess of  bulbs at their rated voltage, continuously until
50% have burned out.  Therefore, the 25 Watt bulb that you so carefully
placed in the bottom of your rod storage enclosure will probably last
several years because it burns continuously (if you don't drop cans of
rods thereon...)

To extrapolate on the above theory, you can buy 240Volt bulbs with a
standard base.  A 240 V, 100 Watt bulb consumes 50 Watts at half
voltage(120) so if you put one of these in the impossible to reach
fixture above your grandmas attic stairs, it will last 10 years...  They
also make "rough service" bulbs that have extra bracing of the filament
; these are great for drop lights that get knocked around...that's why
they are called drop lights...
The above is probably more than anyone wanted to know about light bulbs
but now you know that you have additional options for peace, prosperity
and longevity...

Stephen McGehee, Publisher
Irony - the sketchbook of an apprentice blacksmith

_______________________________________________
http://mailman.qth.net/mailman/listinfo/theforge=20
theforge mail list group photo site is
http://www.photoaccess.com=20
Login:  [email protected]=20
password:  anvil
___________