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RE Flourescent Lamps, efficiency and temperatures
I previously recalled and stated that PCs are about 35% efficient.
What a generous memory I have. Flourescents generally can convert
about 20% or so of their input energy to visible light. PCs are
probably closer to 25% because the smaller diameter helps to keep
mercury vapor at a higher and more efficient operating temperature.
Some high pressure sodium lamps achieve efficiencies of about 30% or
more, but he spectrum is very very narrow.
In terms of mercury vapor temps, the typical preferred operating range
is 40-80 degrees C or 104 -176 degrees F with the maximum efficiency
usually close to 50 degrees C or roughly 120 degrees F. Above or below
those numbers and the amount of light produced per watt falls off more
than 20% below the maximum possible. Note that, if the gas inside the
bulb is about 120 degrees F, then the glass will probably be a bit
cooler, perhaps as low as 100 degrees, depending on ambient conditions.
The temperature ranges are determined largely by the properties of
mercury.
Sorry for the earlier misstatement.
Scott H.
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