Talk:Halogen lamp

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Controversy?[edit]

I've seen references to the fact that halogen lamps aren't very efficient. For example: "But like most conventional forms of domestic lighting, halogen spot lamps are terribly inefficient and use far more power than is necessary since nearly all the energy is wasted as heat, which brings with it the further problem that they run incredibly hot and often require fire-rated covers. They also don’t last that well with bulb replacement required after about 2,000 hours of use." http://www.kulekat.com/led-home-lighting/replacing-12v-halogen-lamps.html

I think it would be useful for someone knowledgeable to discuss this controversy on the page and also clarify the distinction between "efficacy" (as used here) and efficiency, the more generally known engineering term. Is this a US/UK thing, or is a looser sense intended? 96.237.170.55 (talk) 04:01, 2 July 2009 (UTC)

All electric lamps - even compact fluorescent, even LEDs - make more heat than light. 2000 hours is a long time for an incandescent lamp and quite standard. "Efficacy" is a perfectly standard bit of jargon when talking about lighting; it's a combination of "how much of the radiation produced by the lamp is visible light" and "how efficient is the lamp at turning wall-plug power into electromagnetic radiation". By definition, for green light at 555 nanometres, the first factor can be no higher than 683 lumens of visible light per watt of electromagentic energy radiated. White light has a much lower lumens/watt efficacy, since the human eye isn't equally sensitive at all visible light wavelengths. Depending on how you define "white" light, the best a white light source can do is around 275 lumens/watt. See luminous efficacy for more.
Even a poor fluorescent lamp makes more visible lumens per watt input than the best halogens, but fluorescent lamps aren't the best solution to every lighting problem. --Wtshymanski (talk) 21:14, 28 October 2009 (UTC)

Questions[edit]

1. If a lamp is referred to as "halogen burner" does that mean it is incandescent or metal halide?

2. What's the temperature range of the filament? Of glass? Quartz?

See reference 1 in the article, which contains a much better description of halogen lamp operation than the entry, and some answers to your questions. (Redcliffe92 (talk) 14:55, 10 March 2008 (UTC))

3. How does a halogen lamp die? —Preceding unsigned comment added by 91.156.21.32 (talk) 21:10, 6 November 2009 (UTC)

New[edit]

I am unhappy about this Article, which has some inaccuracies, is not very comprehensive and has limited references (ref 2 seems unobtainable) I propose to offer the revision below, retaining the sections headed "Safety" and "Handling Precautions". I am unsure about "Halogen Spectra" as the picture is too indistinct to be readable. The spectra will be fairly similar to a black body at the filament colour temperature.

Any comments would be appreciated. (Redcliffe92 (talk) 15:45, 15 March 2008 (UTC))

PROPOSED REVISION Introduction A halogen lamp is an incandescent lamp wherein a tungsten filament is sealed into a compact transparent envelope filled with an inert gas, which may be argon, nitrogen, krypton or xenon or a mixture, plus a small amount of halogen such as iodine or bromine. The bulb stays clean throughout life. The halogen lamp can operate its filament at a higher temperature than in a standard gas filled lamp of similar wattage without loss of operating life. This gives it a higher efficacy (10-30%) . It also gives light of a higher colour temperature (whiter). Alternatively it may be designed to have perhaps twice the life with the same or slightly higher efficacy. Because of their smaller size halogen lamps can advantageously be used with optical systems that are more efficient.

Principle of operation The function of the halogen is to set up a reversible chemical reaction with the tungsten evaporating from the filament. . In ordinary incandescent lamps this tungsten is deposited on the bulb. The halogen cycle keeps the bulb clean and the light output remains almost constant throughout life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some time it will reach higher temperature regions, where it dissociates, releasing tungsten and freeing the halogen to repeat the process. In order for the reaction to operate, the bulb temperature, all over, must be higher than in conventional incandescent lamps, necessitating the use of fused silica (quartz) or a high melting point glass (such as aluminosilicate). Quartz being very strong, the gas pressure can be higher, which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so efficacy) for the same average life. The tungsten released in hotter regions does not generally deposit on the hotter parts of the filament where failure will eventually take place. Regeneration of the filament is possible with fluorine, but its chemical activity is so great that other parts of the lamp are attacked. .[1][2]

The first commercial lamps used elemental iodine, and were known as known as Quartz Iodine Lamps, launched by GE in 1959. [3] [4] Later bromine was found to have advantages, but was not used in elemental form., Certain carbon hydrogen bromine compounds give good results. [5] [6] . The first lamps used only tungsten for filament supports, but in some designs it has been possible to use molybdenum - an example being the molybdenum shield in the H4 twin filament headlight for the European Asymmetric Passing Beam.

High temperature filaments emit some energy in the UV region, and doped quartz or optical coatings can be used to block most of the UV, if this is harmful - where people or sensitive material are directly exposed to the lamps. Hard glass blocks UV and has been used extensively for the bulbs of car headlights. [7] Alternatively the halogen lamp can be mounted inside an outer bulb, similar to an ordinary incandescent lamp, which also reduces the risks from the high bulb temperature. Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.

For a fixed wattage and life, the efficacy of all incandescent lamps increases for lower supply voltages Halogen lamps made for 12 to 24 Volt operation have good light outputs, and the very compact filaments, possible because the voltages gradients are low, are particularly beneficial for optical control. The range of MR16 (50 mm diameter) reflector lamps of 20W to 50W were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. More recently the wider beam versions are available designed for direct use on supply voltages of 120 or 230V. [8]

The MR16 series uses a multilayer heat transmitting, light reflecting film on the reflector. The idea of putting a light transmitting, heat reflecting film on the bulb has been the subject of research for many years. Lamps are now available using this IRC (Infra- red Reflective Coating) which are generally described as "energy saving" since they offer similar performance for about 30% lower wattage consumption. [9] [10].

Voltage, Light Output and Lifetime Tungsten halogen lamps behave in a similar manor to Incandescent Lamps, but the light output is reported as proportional to voltage to the power 3 and the efficacy proportional to the power 1.3 [11] The normal relationship regarding life is that it is proportional to voltage to the -14. Halogen lamps are manufactured with a halogen dose to match the rate of tungsten evaporation at their design voltage. Increasing the applied voltage increases the rate of evaporation, so at some point there may be insufficient halogen and the lamp goes black, so over-volting is not generally recommended.. With a reduced voltage the evaporation is lower and there may be too much halogen, which can lead to abnormal failure. At very much lower voltages the bulb temperature may be too low to support the halogen cycle, but by this time the evaporation rate is too low for the bulb to blacken significantly. There are many situations where halogen lamps are dimmed successfully, but whether the very extended lives predicted by the formula are achieved is doubtful, and is in any case dependent on the lamp construction, the halogen additive used and whether dimming is normally expected for this type.

bulb picture[edit]

Please provide a better caption for the bulb picture as the proposed caption is not English and does not explain the relevance of the picture to the article. What does "Halogen lamp Replace of incandescent light bulbs Europ < 2009" mean? --Wtshymanski (talk) 15:30, 25 May 2009 (UTC)

Now the mystery bulb has gone from 42 watts to 105 watts. *What* is the bulb in the picture, and *why* is it in the article? I've changed the caption again, but I don't know what it is and can't figure out its relevance from the image page. Whoever originally wanted this picture in the article should explain its relevance. --Wtshymanski (talk) 13:48, 27 May 2009 (UTC)

Spectrum[edit]

The spectrum picture is not very useful - it doesn't show most of the visible light portion of the spectrum, which is the whole point of a lamp. I'm taking it out till we can find a good line drawing halogen spectrum. --Wtshymanski (talk) 14:33, 11 November 2009 (UTC)

Applications: Portable Convection Oven[edit]

I just bought one of these and wanted to read up on the science behind it. I was surprised there was no mention of this application of halogen lamps.Janko (talk) 15:48, 21 December 2009 (UTC)

Issues[edit]

1. Halogens are low efficacy/efficiency compared to CFLs & many LEDs. A lot of people don't realise this.

2. Halogens are widely used in downlighters, which are very energy inefficient. Its easy for a room that took a 100w incandescent to need 10x 50w = 500w of halogen downlighting to achieve enough light

3. Rubbing alcohol was mentioned to clean the lamps: this is alcohol with added oil, is that not surely the wrong stuff to use? Meths would be more appropriate.

4. Lowish power mains halogens (50w and below on 240v) have much poorer efficacy or life compared to LV ones. They're also very vibration sensitive, and many premature failures occur.

5. Downlighter clusters also suffer high lamp failure rates. 10 lamps of 1500hrs eash will need 10 new lamps per 1500hrs, or on average 150hr relamping interval. 82.31.207.100 (talk) 09:16, 15 February 2010 (UTC)

Cite it and write it. Looks like valid points, but do you have a citation? --Wtshymanski (talk) 14:47, 15 February 2010 (UTC)

Yes, but ...[edit]

... what TEMPERATURE do they typically run at? That being the precise question I came to this article to look up :-) - David Gerard (talk) 19:25, 11 February 2011 (UTC)

Fair question. I'll do some updating sometime. Vacuum lamps run from perhaps 1500C to 2200C depending on who's talking and on the purpose of the lamp. Halogen lamps From perhaps 2200 C to 3100C. Also depending on function. YMMV. JonRichfield (talk) 20:30, 8 August 2011 (UTC)

Is this answerable? Wattage, enclosure / cooling, and many other factors play into this. Where I work I run everything from 35W MR11 lamps to 750W HPL's. I know they don't get equally toasty... LightRobb (talk) 22:03, 18 April 2012 (UTC)
Ummm... I read the question as referring to the filament temperature, which is what determines the kind of illumination. In what I regard as the unlikely event that David meant the temperature of the entire unit, could he please repeat his question in more specific detail?

JonRichfield (talk) 12:29, 19 April 2012 (UTC)

Request for citation[edit]

I note my request for a citation was removed without providing a citation, in a series of edits by a single user. The paragraph in which the request was made is unchanged from when I made the request. I have reinstated my request, and am now supporting the template request with more specific details of what I am requesting and how it may be satisfied.

I am requesting a citation from a reliable source allowing verification of the statement:

"When this is done correctly, a halogen lamp with UV inhibitors will produce less UV than its standard incandescent counterpart".

The citation should be placed in the article just after the statement, and the cited source should specifically verify the claim made by the above statement – that halogen lamps with UV inhibitors can produce less UV than a standard light bulb if done well – per WP:CHALLENGE. Regrettably this is not a field in which I am expert and my own search for a suitable reference has failed thus far. As the consequences of leaving this statement in the article for a while appear to be mild in all regards, I am content to give a reasonable time for verifiability to be established.

--MegaSloth (talk) 23:46, 16 December 2011 (UTC)

In the finest traditions of Wikipedia - "7 is bigger than 3" , "Citation needed" and the tag will stay there till the end of time. --Wtshymanski (talk) 04:41, 17 December 2011 (UTC)

Purple flash?[edit]

Earlier today the article included:

It is possible to determine whether a particular lamp uses bromine or iodine without breaking the glass envelope. If the current through the lamp is slowly increased from zero to a point just before the lamp starts to emit visible light, there is a short current range where iodine makes itself visible by turning purple. Bromine has no such effect.

Where is this documented? I haven't read everything there is on halogen lamps, but surely this would be noted in several places? I've taken it out. --Wtshymanski (talk) 14:26, 20 March 2012 (UTC)
Cite error: There are <ref> tags on this page, but the references will not show without a {{reflist}} template (see the help page).