Re: Season misconceptions in newspaper

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

Phillips make available leading information on a great variety of their lamps.
(My mind echoes "Gloelampfabriken" (sp?)  whenever I read the
trademark "Phillips".)
It is unfortunate that they do not offer a "recommended Retail Price" guide -
possibly because of the variety of countries where their products sell.
Of the sixteen 60 watt incandescent lamps I looked at in two  design variants
"A15" and "A19",  the life claim varied  between the following values:
1000, 1500, 2000, 3000, 3500, 8000 hours.

These 8000 hour lamps were offered as Krypton fill long life clear traffic
light lamps
giving 81000 lumen.hours per watt   (610 lumen)
The soft white  1000 hour lamp gave 14,300 lumen.hours per watt    (860 lumen.)

Always wondered what virtue Krypton fill offers. Perhaps this is it!

Brian Whatcott    Altus OK

At 10:57 PM 6/22/2003 -0700, Bernard Cleyet, you wrote:
> /snip/
> Until the advent of concentrated arc lamps and then inexpensive LASERs,
> Std. lab lamps were W ribbon filaments operating at 6 => 14 V.  The
> 30A/T20/4 at 30A has so long a life that it's not given in that
> table  It's a 60 cd; T (color) 2300 K; 225 W lamp.  If "over voltage" to
> 640 W; 700 cd; 3000 K, it still has a long life.  However, another table
> gives its life as 300 hr. at 3100 and 100 at 3200 (color temp.)
>
> A tungsten table gives the evaporation rate of W as a function of temp.
> (deg. Kelvin; color temp. and thermo. temp. differ by ~ 50 to 110 deg. in
> this range).  If one assumes that life is proportional to the rate, I find
> the life is exponential with one order for ~ every 200 deg.  Therefore, at
> 3,000 deg. the life should be ~ 1k hr. and at 2300 ~ > 100 k hr.  Long
> before this, the envelop will be darkened.
>
> bc
>
> p.s. I think it was I. Langmuir's * great invention to add an inert gas to
> reduce the evaporation rate.  Again a trade off: much longer life, but
> reduced efficiency due to the thermal conductivity.
>
>
> *  Yes (1913), and I discover that H. Becquerel (1867!) was the inventor
> of the fluorescent lamp!
> /snip/
> >A rational  lamp selection parameter would be
> >  lumen.hours per watt.cent (of first cost)
> /snip/
> >Brian Whatcott    Altus
> >