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Understanding UV lamp specifications
741:
I'm trying to understand UV lamp specifications. Here is an example from Helios, https://www.heliosquartz.com/wp-content/uploads/2016/01/Helios-Quartz_UV-LAMPS_eng.pdf
Measurements "represent average values at 1 meter".
For example type HCL5W/G23: Is the final column the total UV output from the lamp i.e. the total UV flux (therefore regardless of distance)?
The next-to-last column gives uW/cm2, so this will be measured at the given 1 metre distance I assume.
So as I see it, the 11W is distributed over about 0.5m2 which is about 22W/m2 or 22/(100*100) = 22mW/cm2. <--- My mistake, not 11W
Here is a copy & paste of the top row from the data sheet
HCL5W/G23 12,5mm 83mm 5W 180mA 34V 9µW/cm2 1W
At 1m radius, diameter is 2, circumference is 3.14*2m = 6.28m, and length of area illuminated is then 83mm* this value, i.e.
6.28*0.083 = 0.52 m2.
The 1W is distributed over about 0.5m2 which is about 2W/m2 or 2/(100*100) = 0.2mW/cm2 = 200uW/cm2. <---
But the value shown is just 9 uW/cm2.
RoGeorge:
Only a fraction of the electrical energy that is put into the lamp is transformed into the desired UV light. The rest is wasted on other side effects, e.g. heat.
Nusa:
That applies to incandescent bulbs in general, including the typical household bulbs that most of us are still using in at least some fixtures. Even the best of them still lost 90% of the energy as heat. Which is why it was so easy for alternative technologies to save energy.
To the OP, it doesn't change the response, but you seem to be jumping rows when reading the chart. You started with 11W, quoted the output for the 9W lamp, then mentioned the output value for the 5W lamp. Very hard to follow your argument when you do that. In any case, notice the output wattage is actually listed on the chart in the very last column. Subtract that from input wattage and you have your non-UV energy consumption for that bulb.
RoGeorge:
Also, the lamp model given as example, the power and the calculations doesn't make sense to me.
I'm reading that table like this (for the first line):
5W electrical power in, 1W optical UV power out.
For an ideal 1W light inside of a 1 meter sphere (not circle), that 1W will generate about 7.96\$\mu\$W/cm2 at the sphere surface.
However, the datasheet says 9\$\mu\$W/cm2 instead of only 7.96\$\mu\$W/cm2, maybe they considered some other shape than a sphere, or maybe the 1W is the guaranteed total power, but the measured lamp generates slightly more, IDK.
Zero999:
--- Quote from: Nusa on May 13, 2020, 06:21:44 pm ---That applies to incandescent bulbs in general, including the typical household bulbs that most of us are still using in at least some fixtures. Even the best of them still lost 90% of the energy as heat. Which is why it was so easy for alternative technologies to save energy.
--- End quote ---
UVC lamps aren't incandescent though. Mercury UVC lamps have efficiencies of 30% of more. A good data sheet will provide both the power output as well as power input. The over all assembly will be a bit less efficient as some energy will be lost in the ballast and reflector.
Page 12 gives the efficiencies of their germicidal lamps.
https://www.heliosquartz.com/wp-content/uploads/2016/01/Helios-Quartz_UV-LAMPS_eng.pdf
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