Onto the question of what makes one lamp a long life and another a high output lamp when they both have the same wattage,
voltage and
filament type and size.
This believe it or not is one that's really hard to find out about even when talking with engineers at the manufacturers. While in meetings with them I have asked more than one manufacturer this question and never gotten a more simple response than a in general, it depends upon the amount of "doping" of the materials and metals making up the
filament which determines the expected life that
filament will last. This is also studied in the Osram low
voltage lamp free PDF I have noted elsewhere on the forum many times such balances about lamps the
book goes into. Darned good read.
In further detail one must study the term "doping" of the
filament. What this means is that the
tungsten filament of a lamp is not just
tungsten but a sort of alloy of it.
Tungsten by itself is rather hard to work and refine, much less can if I remember correctly be very fragile and while longer in resisting breaking while incandescing during resistance to
current, has it’s own problems. It also burns as a norm for all
tungsten lamps at somewhere between 3,500̊K and 3,600̊K depending upon what source you are reading info about it from. This is were
color temperature of a lamp directly relates to how hot that lamp is burning and how much of the
filament is burning off or how short that lamp will melt
thru as opposed to burn for 100 years. It’s also metal so keep flexing it or heating and cooling it and you get something that will become brittle. Below will be a mention of a bell curve in
color temperature. While for the most part in the section of seating in class at school certain members will be at the lamp’s rated
color temperature, other parts will when on a bell curve be getting better grades in school and others lesser grades in school such is the bell curve rater than linear curve of light given off by the lamp. A 3.2K lamp does not just have a
color temperature of 3.2K, it’s all wavelengths - this is just the main part of the light provided. Those amounts of the
color temperature of a lamp at 35K or above will tend to burn up and burn off the
filament, while those cooler parts would tend to last longer. What is done in doping the
filament effects to what extent the
filament is allowed to approach surpass 3.5K and in general dopes or dummies down the bell curve of
color temperature that lamp burns at in general. In other words, it’s making a 120v lamp into a 130v lamp, or high output into a long life lamp, or changing if most of the class received a “D” for a grade, them thus all getting “C’s.”
While the above 0.4% ratio above that of the change in a
filament due to percentage of
voltage applied to a lamp might seem small, remember we are talking about lamps that for our purposes have between 2,800̊K and 3,500̊K in
color temperature ratio. 0.4% Than when over a couple thousand adds up for each percentage. This especially in the 3,200̊K range of
color temperature for a
stage and studio
halogen lamp which due to the "
halogen effect" re-deposits spent/burned up parts of the
filament back onto the
filament so it burns again, to some extent there is still some wasted
filament getting lost or deposited on the wrong parts of the heat source/
filament.
Note due to air flow circulation witin the lamp, what is burned up from some really hot parts of a lamp - such as near the center of a AC lamp or near the (-) side of a DC lamp, will get instead of re-deposited back where it burnt off, instead by air flow get deposited onto the more cool part of the
filament thus would be why even a
halogen lamp will die out.
This is the
halogen effect, while the iodine and other chemicals within the lamp does catch particles of
filament and re-deposit them, the hottest part of the lamp is simply too hot in heat pressure to easily re-deposit
filament back onto it, much less some particles get trapped in less efficient parts of the
bulb shape. Now get into some even more rare than iodine type chemicals such as Krypton (somewhat in green
color temperature) and more especially Xenon that is really rare, or I expect radioactive forms such as KR-85 and add that to the
halogen mixture of bromine/argon/iodine and other chemicals in the gas of a
halogen lamp, and you have a lamp that better can handle high temperatures and re-deposit the
filament where it's needed.
Xenon fillers are really expensive but absolutely necessary if you want to operate a lamp near the melting
point of
tungsten if even for a short period of time. For the most part, you won't find xenon filled lamps for other than say the HES Trackspot that uses a xenon filled lamp that is only rated for 50 hours when operated at or near the melting
point of
tungsten in general. But what a 50 hours in intense beam of light there is. You can get a longer life version of lamp for the Trackspot, but you quickly get into a more
halogen version of it's
color temperature and lower output. No matter what chemicals you add to the
halogen effect to make it more efficient, at some
point the general rule of exchanging 3.6% output and 0.4% of
color temperature for each percentage of
voltage difference which reduces or inversely lamp life by 12% (dependant within 1% what source you read), this is a rule of thumb one cannot much get beyond too much. A 130v lamp is often rated for the same amount of output and life as a 120v lamp as a 115v lamp when operated at the specified
voltage. All a question of rated
voltage in providing the same specifications while especially operating at other than that specified
voltage/volume.
To some extent a
HPL or modern lamp might have some xenon fillers to them to allow them to burn hotter, but not a lot of it in the lamp is affordable or to a great benefit at the moment.
In addition to
reflector qualities of the glass surrounding a lamp, you also won't find much in the way of xenon fillers. A T-Shaped
bulb is just too inefficient in where that heat flow is going to increase the
color temperature of a lamp much more. Think of a tube of glass with hot spot in it's center. Than a great wind inside of it and that's the
halogen effect. While a lot of that wind will circulate from cold to hot back to the
filament, some of it is still going to get less pressure in going back to the
filament and instead become a sort of tornado of lower pressure in never getting back to the
filament towards the extreme ends of the tube of glass not closest to the
filament. Thus some of that
tungsten filament is lost to replentisment also in addition to the re-deposited metal preferring to re-deposit on the slightly more cool part of the
filament due to pressure/heat. Hotter parts of the lamp such as those on a DC
system where the
current comes into the lamp, or in AC where the center of the lamp, coils to the
filament are warmed by adjacent coils in the
filament have a certain amount of more heat
conventional oven like applied to it than parts of the
filament say towards the lead in wires where it’s less cool because there is less heat adjacent to it due to conductance to heat/light waves. What’s going to be easier to re-deposit the heavy metals of the
filament, this to where it’s cooler and of less pressure or there where it’s hottest and re-circulated air is more pushed away?
This vacuum within a tube and various pressures within the lamp dependant upon where especially a T-Shaped
Leko tube lamp will
play a large factor into various pressures within the tube in the heating and cooling cycle.
For this reason also a
dichroic coating within the lamp so as to convert IR energy/heat that otherwise is not used is not of much use within a lamp at the moment unless that
bulb is a
globe coincentric around the
filament directly reflecting back to the
filament. On some lamps, this reflected heat while light passes
thru the glass, the IR is reflected back into the
filament of the lamp in further heating the
filament. You thus get a lamp that not only has
voltage/resistance flowing
thru it in getting hot enough to incandess - burn that
filament wire almost to melting
point, but also there is heat applied to the
filament from the outside in getting it hotter still in needing less
voltage/amperage applied thus wattage.
In the above, I mention a certain thermal
effect proximity to what’s the heated part of the
filament has to also in addition to applied
voltage heating the
filament of the lamp. The closer the
filament coils in proximity to each other also the more efficient the lamp in other than resistance of the
filament heating of the
filament. This thus is in addition to a more compact
filament shape being by way of
reflector of the
instrument efficiency why say a
HPL lamp will be more efficient than a FEL lamp. Proximity of the
filament grid as long as the amperage or magnitude of
current in the
filament is not sufficient to arc between
filament coils tends to re-heat adjacent coils of the
filament in making that say
HPL 375w lamp as bright as say a 500w EHD lamp to some extent.
Since most of our Lekos have tubular instead of globular shapes, a
dichroic coating on them to reflect the IR waves of light won't do much cost effective good but in changing the geometry of a lamp, it’s an option for the future in further heating the
filament other than by way of resistance, that
filament to incandess at a lower resistance to
current. At this
point it is probably more a question of given a specific dia. of a T-shaped lamp, and given a certain amount of volume inside a lamp needed for cooling what
globe shaped
dichroic lamp would be required to make for a replacement to the tube shaped lamp we currently use. Just as the T-4 dia EGE easily replaces the T-12 DNS in size due to
halogen effect, it’s still a statement of cooling of the lamp. The
halogen gas within the EGE allows for a hotter burning lamp but still has a certain amount of cubic area to it. Make a ball of a lamp instead of a tube and the dia. would need to increase. This in addition to the length of te EGE not really needing it’s extra length but due to the length of the old
incandescent lamp it replaces, a
globe of a
dichroic larger dia. lamp would be required but on a longer stick of extension from the lamp
base due to what lamp it replaces just as wit the DNS. Such a long extension is also fragile and prone to failure as another obstacle in making the S-4
Leko having a
globe shaped
dichroic lamp fit inside it. Remember that the larger the dia. of the lamp that goes into the light, the more of the
reflector is cut away in
fitting the lamp in. More of the
reflector/ellipse cut away, the less efficient the
fixture. Constant trade off’s in designing both lamps and fixtures and at the moment it’s probably in this
dichroic coating to a lamp not possible given the
fixture to upgrade more efficiently.
This also in lamp size and shape is complex as with every part of a lamp. Old
incandescent Leko Lamp bulbs used to be T-28 and larger in times. (The T-Number designates the shape of the lamp, the 28 number designates how many 1/8" increments that lamp is in dia. No idea on why it's 1/8" increments but that is the measurement.)
Part of burning or incandessing is in pressure or ability to combust. No air or in this case pressures within the lamp surpressing burning up but not so over oppressive that it can't burn, and you get no combustion. Have a lamp with no pressure surpressing it's flame and you get a flame or melt down following it in resistance without restrictor.
First you have the vacuum tube as ancient in lamps. Remember them of you older tech people throwing household or better yet surplus TV lamps/parts at brick walls in listening to the "pop"? You won't find many vacuum tube lamps under 40 Watts these days. Argon, Nitrogen, Bromine and other high electron elements are much more effective in suppressing the burning up of the
filament in a positive rather than vacuum atmosphere. A negative vacuum atmosphere when the burning of the
filament causes pressure normalizes than becomes plus some AU. You than have a lamp that both resists both suck and push. Instead most lamps just have to resist push of pressure.
Something of a science class question or study into why something with a high electron or higher on the what ever that scale it is count is more resistant to surpressing the burning up of a
filament but it's the case here. A argon filled lamp will surpress better than a vacuum lamp and be less dependant upon a good
pinch seal of the lamp to work dependably. Why is it that Xenon is better than Krypton or Bromine otherwise?
So you have surpression of the
filament as one thing that dictates how long a lamp can last in addition to
globe shape. (Getting back to the subject.) A xenon filler will allow that
filament to burn hotter or in the same theory if the
filament is burning at a more normal temperature, should allow that lamp to burn longer at that temperature at only an increased price of the rare earth gas Xenon. Just as a
halogen lamp lasts longer than a
incandescent (lacking the special re-depositing of
filament gasses and in no way otherwise for the most part different than any other
incandescent lamp) you would find that a xenon filled
stage and studio lamp would last longer in life than that of one that does not have it. This in addition to kryptoin in small amounts is already done to some extent that is higher output but still cost effective. Krypton is another type of filler above the
halogen mixture that will add to burning or operating temperature. Not because of Superman comics but for other reasons, kryption as a chemical still is not as high in burning temperature as xenon fillers but +has a green tint to it.
The shape of the lamp also will
play a factor in how well those gasses are able to
halogen effect the spent
filament back onto the in-tact
filament. It in those more or less lost zones of the
bulb shape in a low
voltage (more architectural lamp) while under dimming can be burned as a lamp too cool for the
halogen effect to take place with instead the iodine corroding and attacking the molyodenum foil of the lamp (where the wires or pins of the lamp transfer from pin to
wire witin the
pinch seal) or the glass attached to this piece of metal in having dimmed
halogen lamps that at best work as well as a
incandescent lamps, at worst last a shorter amount of time than one. Don't worry, 120v lamps burn hot enough that even dimming to 10% is sufficiently hot it's not a problem. Low
voltage stage and studio lamps such as in a 12v
cyc light using MR-16 lamps are also safe in theory due to the in series operation of them. Just an individual low
voltage lamp when dimmed that could have a problem with getting hot enough due to the shape of the glass and how that wind within a
halogen effect lamp works.
On the other
hand also most companies have come out with their own improved
pinch seal technology no matter what the
voltage or type of lamp. P-3 tecnology from Philips being the most famous and published amongst all brands of similar technology. 120v and arc source lamps also have
pinch seal problems that while not persay the
filament not getting hot enough, this is the less efficient part of the lamp and one where once pinched tight to hold the gas in, it also offers an exit to the gasses within the lamp.
So we have
bulb shape and wind flow. Related and specific to this we also have
bulb shape which effects as if the tube of glass were a
reflector as in a interior coating of
dichroic metal particals a internal
lamp globe reflector that's not really possible for most
stage and studio lamps due to shape. At some
point, once a more high temperature xenon gas (expensive) is introduced to more extent to the
globe of the 120v and high wattage lamp, you can expect that the lamp shape/quartz glass can also be reduced in size or at least become more
reflector in shape in reflecting the IR heat once
dichroic coated back to the
filament the otherwise useless heat of the lamp. This will reduce the wattage of the lamp necessary to heat te same lamp due to wattage/resistance once warm.
Otherwise an alternative is to as with some liquid filled xenon lamps used on
IMAX theater lamps, do a liquid filled instead of gas filled lamp so as to further reduce the temperature of the lamp thus allow it to burn hotter still. This liquid filled lamp technology is still years off I think, but raises certain worries amongst lamp engineers when you mention such concepts. It’s either some deep secret or some worry about other manufacturers technology above their own. In a serious way, slip in the concept of a liquid filled say
HPL lamp and it causes instant interest with the engineers. Don’t know much about how such a liquid filled lamp works, but I expect they also don’t yet.
And now back to what it takes in difference between a high output and long life lamp in "doping" or to the best of my knowledge in I'm a
Master Carpenter by trade but did buy a few $K in lamps today description of my understanding of the subject.
Ok, I work as the lamp buyer for one of the largest 5 or 10 lighting companies in the world and as such in the last about 6.1/2 years have had to learn the specs on what I buy in detail over hearing a Menards commercial for "
halogen lamps" and thinking that they have some magical brightness quality to them in general (note the above
incandescent fresnel lamp that is higher output than that of a
halogen version.) I also have to field requests at times from famous designers normally by way of corporate show account executive requesting a
halogen lamp that is
daylight in
color temperature because that's what their design calls for. Here I am still carpenter by training for the most part before now in saying, urr, the
filament of a
incandescent heater/resister
filament burns up at about 3,500̊K so it's not really possible to purcase any 5,000̊K
filament halogen lamps. Perhaps Menards with their “
halogen” lamps might help you with this request instead.
While you can
gel or get some coatings on the lamp to make it seem that hot, you also will loose a wee
bit of light in what such light waves - most of it's beam in a curve from about 1,200̊K to 7,200̊K is being blocked. (My estimate)
Color temperature is where the bell curve of
color temperature averages out but it's
drop off is steep in providing only a little light in the 5K spectrum of light. This is why
incandescent lamps don't make good UV lights (some but not much UV-A spectrum) and why the
incandescent lamp is more like sunlight in natural light than an arc source of light -
fluorescent to moving light. Such lamps have a sort of bell curve also but instead of a gradation to it's beam of light with all colors making up the white light, it's more spikes of light in certain wavelength designations and not a full spectrum dependant upon the refinement of the lamp. What a arc source lamp looks like under a
prism would be related to it's
CRI or color
rendering index - another subject.
In getting back to
filament lamps and why one type of lamp having otherwise the exact same specifications as another lamp can be of longer life we look at what other metals and compounds are alloyed into the lamp's
filament to make it last longer in exchange for burning up really fast. This in addition to the above filler and
globe shape.
It should be expected that no
tungsten filaments are completely
tungsten. This
tungsten was a
filament metal that in history was found early on necessary to while it is most effective as a
resistor, not a efficient piece of metal to shape as needed, or easy to keep long lasting. Instead other things are added into the metal.
How much say steel is added with the
tungsten might determine how well the
filament in keeping the exact same size of
wire or has some amount of
shock resistance such as the difference of when a
filament has to heat up from cold, it allows energy to resist the flow of
current as opposed to let it flow easily and not burn up as fast. Should on the other
hand you increase the size by way of dia. of that
filament wire it cold handle more
current. On the other
hand should you reduce size or lengthen the
wire it would resist more
current.
So and this gets beyond my main study, at say 120v, you would tend to need a more thick
filament size or say two coiled coil filaments to produce more
current to flow
thru the
wire than a
filament say designed for 110v. In resistance and given the same material making up the
wire, the less resistant to the flow of electrons, the less incandescing that
filament will be and also better able to deal with heat that
filament will be. A 120v lamp will have less resistance than that of a 110v lamp given all else is the same other than what is necessary to make the 120v lamp have the same resistance to
current as the 110v lamp which by way of lesser
voltage needs less of a
resistor to it.
So in size of
filament and it as length, the smaller the size and longer the length or any combination of that you have, the more resistance you also have. More resistance equals more heat thus more light and wattage. This all assuming the same
voltage rating on the lamp. Higher the
voltage rating in considering size or length and you increase the resistance of the
wire. Resistance equals to some extent work done or wattage thus in gaining the same wattage of lamp but for a higher
voltage and you need to increase the size of the
wire or shorten it's length to compensate just as if you were to hire it's wattage.
Stainless Steel has more resistance to
current flow than Aluminum. Copper has less resistance than Aluminum. Gold less resistance than Copper, Platnum less resistance than Gold. Given these slight details to
current flow and others, change even the percentage of these metals within a
filament and you have something that in keeping the same size and length of a lamp’s
filament will either increase or decrease the lamps life. Granted in doping of the
filament, you get less resistance to
current thus less wattage or output/
color temperature, for the most part in this way you do increase lamp life. Cooler that
filament incandescess as or further away from 3.5K it gets, the longer it will last.
This is a prime difference in what goes into the doping of the
filament of a lamp, why at the same
voltage and wattage
rating, much less
filament type and size you can have a both long and short life version of the same basic lamp.