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High Pressure Mercury Lamps

Sigurthr

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Haha, sweet haul!

Yeah that's why I do ghetto style installations of these lamps, it isn't worth the cost to find a real fixture.
 



trencheel303

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Is this little hole in the cap normal for an MV lamp?



I'm guessing it's harmless as all the fun happens inside the arc tube and this looks like it's outside the arc tube, perhaps it's for cooling?
 

DashApple

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Is say its normal , I looked at the lamps I have but as they are 1 and 1.25Kw they have ceramic inserts instead but they do have two holes in .

I'll check the 400W and 250W ones I have .
 

Cyparagon

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That's where a cathode is soldered/welded to the screw base.
 

trencheel303

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Ah right, that's fine then. I thought it would be nothing serious.

After the kerfuffle I've had recently it looks like I have actually managed to secure myself an Arc:


I am giving thought to re-gearing it for mercury and using the 80W lamp I just got. A mercury lamp in this lantern would be quite quirky but it'd work just fine. Old meets new.
 

trencheel303

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To bump this thread with something relevant; I acquired my first set of clear mercury (MB/U) lamps a few weeks ago - and not just any old crapola, these are Iwasaki (EYE) mercs, apparently regarded as some of the best modern ones.

To say that these are chuffin' lovely is an understatement.


Colour rendering might be Shi'ite, but that never stopped me liking SOX nor would it stop me liking these.


Lovely little bulbs and surprisingly a nice, clean "white" with a tinge of blue, not an awful dingy green or anything like that. Got to be one of my favs although the flicker from mains voltage does get to me a bit after a while.

Actually prefer them to fluorescent mercs - obviously you don't get the red band at all with these but there's just something magical about the light they produce; that and being able to see the arc dance with safety glasses on is on a whole nother level.
 
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Sigurthr

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Awesome! I've only seen a green color from the cheapest of bulbs. Many cameras seem to exaggerate the green, at least to my eyes, which perceive it as a cool white.
 

Cyparagon

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Mercury is mercury. You can't vary atomic transition levels between manufacturers. It's not the price of the lamp, but the age. As the lamp ages, electrode material is sputtered onto the arc tube. This material preferentially absorbs shorter wavelengths. Take out some of the blue, and it's clear how these lamps can appear greenish as they age:

 

Sigurthr

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You can't vary the Hg transitions but you can vary the operating pressure and the envelope transmissivity. Sputtering of course causes green preference, too. If you vary the pressure alone you get different spectral weighting to the lines, which is why pulse start lamps have a different color temperature than regular lamps. Also the safety lamps with internal explosion shields have additional blue band fluorescence from UV absorption.
 

Cyparagon

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You can't vary the Hg transitions but you can vary the operating pressure and the envelope transmissivity.
Arc tube is pure quartz. All manufacturers use quartz - no exceptions.

Pressure doesn't change the color much, but it can cause broadening of the lines if it's high enough. Compare low pressure lamps (e.g. germicidal) which are a cooler white. Compare UHP lamps which are still white. All else equal, pressure cannot cause a green shift.

Besides, pressure is a standard. If you change the pressure, the voltage changes, and the ballast will not work properly with the lamp.

pulse start lamps have a different color temperature than regular lamps.
I've never heard of a pulse start mercury lamp. I've also never seen a mercury lamp with a blast shield, since they don't explode. You're talking about metal halide lamps I think.

I'm talking about mercury lamps. Of course metal halide lamps vary a lot in color temp and spectrum, but that's because of the various metal salts.
 
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trencheel303

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According to some friends on LG, who helped me out with buying US mercs, EYE have a pulse start range of mercs called "Moon Pulse", that run on pulse start MH ballasts.

It's legit:https://www.1000bulbs.com/category/moon-pulse-mercury-lamps/

I don't know about cheap mercs greening out quicker but I've seen some with a pitifully thin phosphor (I have a venture with a phosphor that's not much cop) and there are brands like Caster which the Americans reliably tell me are utter crap and last about a year or so before dying or cycling...
 

Down with Umbrella

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I think I might pick up a couple of these, they seem pretty cool. Very steampunk because you can see the inner workings.
Great thread!
Thanks for the link trencheel303

Looks like I'll need to pick up a ballast also. Hm
 
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trencheel303

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Umbrella is it the MH or mercury lamp you're after? I think the guy in eBay still has some of these mercs I bought and he is actually in the USA.
 

Down with Umbrella

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I actually went to the link trencheel provided. That moon pulse bulb looks interesting. I see that on that same website 1000bulb.com they sell the 100W ballasts recommend in the specs. $25 there as well. A higher wattage ballast would be interchangeable?

I'm building a few custom bench lights and I want to add bulbs to match the aesthetic appeal of the lamp. I'm not necessarily looking for the best light colour.
 
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trencheel303

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Well, normally a ballast requires a lamp of the same rating. So a 175W lamp belongs on a 175W ballast. There are exceptions, like SON-H lamps which retrofit to merc ballasts of different wattages, because they match the current rating of the less efficient, higher rated mercury lamps. Generally I think as long as the current and voltage that the ballast puts out is at or close to the arc tube's specification, it will run fine. You can even under drive or over drive lamps moderately for a short time without an ill effect. I ran an 80w fluorescent merc on a 70W son ballast for a few days with no noticeable effects.

I assume you do know that a 175W hid lamp of any type will be enormously bright as a desk light, though?!!
 
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