Xenon-filled bulbs run at higher filament temperatures than those with Krypton fill and according to info at http://www.carleylamps.com/
they provide the maximum CP/Watt, but Carley doesn't provide lumens while most other bulb manufacturers do. So I began to hunt down the information for a comparison. Along the way I found out why Xenons burned more brightly than Kryptons, at http://www.misty.com/people/don/xeincand.html which indicated that Xenon conducts heat less efficiently than Krypton, thereby allowing the filament to attain a higher temperature which roughly translates to glowing more brightly. But how much more was still the question. At http://www.vistalite.com/exp4.htm
I found information comparing bulbs filled with pure Xenon compared to those filled with a Halogen mix, but nothing specific regarding output. Nevertheless this site is informative on Xenon vs Halogen.
I finally began zeroing in on the answer at http://data.energizer.com/
Scroll down to Flashlights, under which are a list of folders; click on Bulbs and look at info under Krypton, Halogen, and Halogen-Xenon (these are the brightest according to Carley, also). For an comparison example, a Krypton-filled bulb, powered by 4D cells, running at 4.8 volts, 0.75amps, has a rated lumens of 51. A Halogen 4D cell, at 5.2 volts, 0.85amps, is rated at 86 lumens. However the Eveready site had no info on pure Xenons.
On further searching I found just that at http://www.eur.lighting.philips.com/
Click on the search button on the top. Enter "flashlight" (without the quotes) on the search line and this will open a list of available documents. The first two, denoted with four stars have the relevant information, but you need Adobe Acrobat to read them. The essential information on Xenons is in the second of the top two listed documents (halogen bulb specs are in the first doc). To continue the comparison of a typical 4D cell powered bulb, Xenons (at least those manufactured by Philips) running at 4.8 volts, 0.85amps put out 65 lumens. Similar comparisons can be made for varying voltages by comparing information at the above Eveready and Philips sites. I don't know who manufactures the Eveready bulbs, but for most of them the voltages, amperages and lumens match the Philips bulb for bulb. A few are off by some percentage, which may indicate a different source for the Eveready listed bulb.
The question I remain having is if I switch out the Carley Xenon Star that I have in my 4D Mag, for a Halogen will I get 20+ lumens. I tend to doubt this as the specs of a Carely Xenon Star for a 4D-cell are 5.3volts at 0.79amps, producing 4.2 watts. An HPR50 (halogen for a 4D-cell) on the Eveready site puts out 4.4 watts (volts X amps = Watts: 5.2 X 0.85). Do 0.2 watts more give me 20 lumens? No way, right? So where do those lumens come from? What am I missing here?
Within a family (xenon, argon, xenon-halogen, etc.) - and within a power range (4D cell, etc) - compare lumens per watt (efficiency) versus manufacturer( philips, GE, osram, carley, etc)-
Carley frequently hits 20 lumens per watt - few other vendors can achieve this and end up in the 15-16 lumens/watt number.
There's nothing wrong with your math- you're just discovering why carley lamps are (I won't say *THE* best) - but one of the best lamps around. 20 lm/watt is a significant achievement in a small bulb - and several of the carley lamps achieve the 20+ number, including their mondo 6V, T t2.5 bulbs used in the surefire 12Z. Even better, I think it gets a 50 hour rating!
I'm certainly not a filament scientist - but there is some science going on here to get the filament at a particular temperature, keept it at that temp, prevent erosion (at least for 10-20 hours which is about all these are good for!)
My hunch is you've just done the research to find the best bulb maker out there - Although I didn't cover as many vendors as you did, I found similar results, and settled on carley as a bulb vendor because of their high efficieincies and willingness to work with me for the product I was developing. It was the lumens/watt number that made it easy, plus carley makes reflectors for all their bulbs, which made it a turnkey solution for me.
I do have a Carly model 712 2cell xenon
and a Carley 716 6 cell xenon on order. You must get these from them since they don't hit the retail channel - the krypton star bulbs are the "magnum star" bulbs found in the mag products, and in select other outlets. The Kryptons retail at ~3, the Xenons ~5. When I get 'em , I'll photograph the comparison with the factory bulbs using new cells and let you see the difference.
From what the carley salesman said, the xenon star bulbs are the best made - they just cost a fortune and don't sell well, so the retail stores don't want to waste "pegs" on the shelves for a lamp that doesn't move.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>The question I remain having is if I switch out the Carley Xenon Star that I have in my 4D Mag, for a Halogen will I get 20+ lumens. <HR></BLOCKQUOTE>
Actually, I think the Carley Xenon Star for 4 cells is about the same brightness as the HPR50 halogen.
From the Carley site, the 4-cell Xenon Star is 6.8 spherical candlepower or 85 lumens. The HPR50 is 86 lumens, so almost the same.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>To continue the comparison of a typical 4D cell powered bulb, Xenons (at least those manufactured by Philips) running at 4.8 volts, 0.85amps put out 65 lumens. <HR></BLOCKQUOTE>