Frequently Asked Questions
The purpose of this page is to address some of the commonly asked questions and concerns about ultraviolet light and about our lamps.
What are fluorescent minerals?
Where do I get fluorescent minerals?
What do the different colors mean?
Why are they called fluorescent lamps?
How does a fluorescent lamp work and what is a ballast?
What are Ultraviolet (UV) lamps?
What makes Way Too Cool lamps special?
What is ultraviolet radiation (UV)?
Where does UV radiation come from?
What is UV radiation used for?
Are Ultraviolet lamps dangerous?
How does UV radiation create a sun tan?
How does a sun-tanning lamp differ from one used to make rocks and minerals fluoresce?
How does UV C disable micro-organisms?
Bulbs/tubes/lamps?
How does the wattage of the tube/bulb compare to UV output?
How long will a tube/lamp last?
What are phosphors?
Are the phosphors always inside the bulb?
Why would I want a lamp fixture with UV B?
What about fans?
How can you tell if the bulb is too hot or too cold?
Do both the 9 watt AC 110V and DC 12V lamps run in "overdrive?"
Why do we need filter glass?
Are the lamps tuned to work with only a SW/LW combination?
How big a display case will a lamp fixture light up?
Battery Power
Microscope lamps
What are fluorescent minerals?
The term "fluorescent" generally means that the material absorbs ultraviolet radiation and re-emits the energy at a different energy level. Fluorescent minerals look like ordinary rocks, except when you expose them to ultraviolet light! Then, they fluoresce with fantastic colors.
Where do I get fluorescent minerals?
Fluorescent minerals occur nearly everywhere in the world. The north-west corner of New Jersey is world famous for fluorescent calcite (red) with willemite (green). Greenland is also relatively famous for fluorescent minerals with a large variety of very bright colors.
What do the different colors mean?
There is no deep meaning to the colors. Most of the time, the fluorescent color is because of trace amounts of some other element mixed in with the basic rock or mineral. For example, trace amounts of uranium (a few parts per million), in silicates such as quartz, agate, petrified wood, common opal, and chalcedony, will cause the material to fluoresce with a strong yellow-green color. Many uranium ores also fluoresce the same bright yellow-green color. Similarly, calcite can fluoresce many colors depending on the trace amounts of other elements. Calcite commonly will fluoresce a shade of red ranging from a dull red to a fiery-red, due to manganese and a small amount of lead. If the manganese has replaced between 3% and 15% of the calcium, the calcite will fluoresce red with the very brightest color occurring around 5.5% manganese. Calcite with trace elements other than manganese can fluoresce green, light blue, bright blue-white, yellow and/or hot pink. There are three ores of Tungston – wulframite, scheelite, and powellite. Scheelite and powellite always fluoresce. Scheelite fluoresces a bright bluish white under UV C, and it often fluoresces pastel shades of yellow, pink, or blue when exposed to UV B. Powellite fluoresces a canary yellow under UV C.Why are they called fluorescent lamps?
They are called fluorescent lamps because the white powder (a blend of phosphors) actually fluoresces in response to the ultraviolet radiation on the inside of the tube. Wikipedia, the free encyclopedia, has an excellent discussion of fluorescent lamps including the history and all technical aspects. Fluorescent lamps on Wikipedia.
How does a fluorescent lamp work and what is a ballast?
Here are some links to some very complete discussions of all aspects of fluorescent lamps and ballasts. The pages even discuss and show wiring diagrams:
http://donklipstein.com/f-lamp.html
https://home.howstuffworks.com/question337.htm
What are Ultraviolet (UV) lamps?
These are special fluorescent tubes/lamps/bulbs that emit ultraviolet radiation — also see above and below. The low pressure mercury vapor tubes that emit UV C radiation do not have any phosphor in the tube — the mercury vapor produces the UV C radiation. For low, medium, and high pressure mercury vapor tubes that emit UV B, UV A, or a blend of UV A and UV B, the inside of the tube is coated with a phosphor or a blend of phosphors. Ultraviolet phosphors are materials that absorbs the UV C and re-emit the energy as UV A or UV B radiation. Refer to the FAQ on phosphor curves for a graph of the curves of different materials.
What makes Way Too Cool lamps special?
Way Too Cool manufactures a full line of ultraviolet lamp fixtures ranging from 9 watt models to 190 watt models in many combinations of UV A, UV B, and UV C. These lamp fixtures are available in 12 volt DC versions and AC versions that will operate on 110 volts or 230 volts AC and 50 or 60 hertz. WayTooCool lamps are designed to be rugged and durable, with solid construction to deliver a long life. In the event of a bulb failure, the bulbs are user-replaceable. Our lamps are designed specifically for mineral enthusiasts and collectors. They can be ordered with different customizations depending on your needs for electrical power, wavelengths needed, and whether it will be for a display case or field use.
What is ultraviolet radiation (UV)?
The electromagnetic spectrum ranges from cosmic rays at one end, to radio waves at the other end. The ultraviolet (UV) region of the electromagnetic spectrum is situated between visible light and x-rays, with the wavelengths of the UV A radiation being shorter and more energetic than violet visible light and the wavelengths of vacuum UV radiation being slightly longer and less energetic than x-rays.
The full UV radiation spectrum ranges from wavelengths of about 100 nanometers (nm) to 400 nanometers and the UV radiation spectrum is usually divided into 4 sections; vacuum UV radiation (also called far or very UV, from 100 nm to about 200 nm), UV C radiation (also called germicide or short-wave UV, from 200 to about 280 nm), UV B radiation (also called mid-wave or medium-wave UV, from 280 nm to about 320 nm), and UV A radiation (also called poster lamp, black-light, or long-wave UV, from 320 nm to 400 nm). Some sources (such as the US FDA), define the range of UV B as being from 260 nm to 320 nm, and other sources give the upper range only as high as 315 nm. In the figure below, the disputed region of the UV B (midwave) is in a shaded color.
| Range | Name | Spectrum | Center Band |
|---|---|---|---|
| UV-C | Shortwave (SW) | 200 - 280 nm | 254 nm |
| UV-B | Midwave (MW) | 280 - 320 nm | 300 nm |
| UV-A | Longwave (LW) | 320 - 400 nm | 365 nm |
Where does UV radiation come from?
In addition to sunlight, UV radiation can be emitted from a variety of sources such as light emitting diodes (LEDs), lasers, electric arcs (especially as in arc welding), xenon bulbs, halogen bulbs, excimer bulbs, and mercury vapor lamps/tubes of low, medium and high pressures.
What is UV radiation used for?
UV C radiation is used extensively for sterilization, purifying, and deodorizing applications in food, air, water, and general surface sterilization processes. This is because the UV C radiation not only deactivates micro-organisms such as: bacteria, molds, spores, fungi, and viruses (by direct irradiation which damages the DNA such that the micro-organisms cannot reproduce), but the UV C radiation also breaks down the chemical bonds of alcohols, pesticides, chloramines, and other contaminants such as NDMA or MTBE.
UV B radiation is the agent that causes human skin to sun-burn and the UV B radiation is needed to start the suntanning process. The lamps/tubes used in suntanning booths usually emit a combination of UV B and UV A. UV B is also used extensively in various medical treatments — especially for skin diseases.
UV A radiation is used for special effect lighting, sun tanning, photo-lithotropy, and photo-chemistry. UV A is also used extensively for curing of glues, special paints, and other finishes.
Are Ultraviolet lamps dangerous?
Yes, there are several SAFETY CONCERNS about UV lamp fixtures to be considered when using the any UV lamp fixture. You must make sure that it is NEVER pointed at anyone including pets. A "sunburn" can occur to eyes or skin.
You should ALWAYS wear UV blocking safety glasses when looking at, or when collecting fluorescent minerals. (You can buy UV safety glasses directly from harbor freight). You can check to see that your glasses do block the UV, by putting the glasses close to a fluorescent rock and pointing the UV lamp toward the rock. The portion of the rock directly below the glasses will remain dark while the rest of the rock fluoresces. It is also a good idea to cover skin that is exposed to the UV and always wear sun block even under clothing as some fabrics can be penetrated by UV much like sun exposure.
For UV lamps in display cases, Way Too Cool uses UV blocking Plexiglas or UV blocking Lexan to make the "window" to be able to look in the display case while at the same time protecting people from the UV. You should always have a UV blocking transparent material for all cases. With regular glass, the UV A shines through and will fluoresce clothing which causes bright reflections on the glass.
How does UV radiation create a sun tan?
(Excerpted from US Patent 4967090) — Skin pigmentation and thickening of the upper layer of the skin called the corneum are the body's natural protective reactions to exposure to & ultraviolet energy produced by the sun; these reactions are the skin's defense against further assault. Skin pigmentation, or tanning, is the result of a complex biological process, and to understand it, one most understand the skin's response to different wavelengths of ultraviolet radiation.
Deep down in the skin are special cells called melanocytes. Once these are stimulated with ultraviolet light, they will utilize substances which they have stored up to produce the pigment melanin. Because these substances only absorb (UV B) ultraviolet light, these UV B rays must be present in order to achieve melanin production. Longer wavelength ultraviolet (UV A) can also formulate melanin but only when there exists enough sensitizing material in the skin to bring about a UV B-type reaction. However, this requires a very high radiation UV A intensity for a long period of time. On the other hand, UV B can induce the same desired melanin production utilizing very low levels of radiation with more frequent exposures. The pale pink colored melanin granules formed in the melanocytes will travel upward toward the horny layer or corneum. They are stored around the nuclei of the keratin cells there. In this manner, the pigment protects the UV B sensitive DNA located inside the nuclei without impeding the other positive effects of ultraviolet light.
In the preliminary stages of melanin production, very little protection is offered to the skin. In order to render the pigmentation process effective, the melanin granules must darken (oxidize). This requires a higher dosage of longer wave UV A. The dosage of UV A must be sufficiently high in order to provide enough energy to initiate the oxidation process. It must be remembered that UV A rays are not as energetic as UV B rays. Long-wave radiation is essential because high doses of short[er]-wave rays will activate substances in the body such as absorbic acid and cysteine which hinder the tanning process. These antioxidants not only inhibit oxidation of pigment but can even reverse the process.
Thus, UV B serves to synthesize the pigment granules while UV A ensure their oxidation. Together they form a light protection mechanism. UV B is also essential in developing the skin callosity in the horny layer or corneum. This light-induced thickening stabilizes the skin to guarantee protection from excessive radiation. After the skin has been exposed several times, this callosity will develop within one to three weeks and can remain for several months.
Most tanning lamps produce a spectrum of ultraviolet light which is similar to that of the sun. Most lamps provide the small amount of UV B necessary to initiate the tanning process while at the same time, providing the UVA needed to darken the pigment (melanin). Ultraviolet tanning lamps and tanning equipment used in the United States must comply with very specific regulations which are enforced by an agency of the Food and Drug Administration. These regulations restrict certain ultraviolet lamp characteristics and require extensive labeling of lamps and suntan equipment. The U.S. FDA defines UV A as the region of 320 nanometers (nm)-400 nm and UVB as the region of 260 nm -320 nm.
In the design of sun-tanning equipment and UV sources it is necessary to consider that tanning ability and tanning characteristics vary from one individual to another. In this regard there are two main factors which should be considered:
1. Skin Type this refers to the (genetic) capability of an individual to produce and maintain a pigmentation in the skin. It is determined by the histologic response of the skin to ultraviolet radiation and classified by the observable effects.
2. Present Skin Pigmentation - this refers to the relative pigmentation level of the skin at the time just prior to UV exposure. Previously well-tanned skin, exhibiting a high level of pigmentation is generally more resistant to erythema (sunburn) and hence may tolerate higher levels of UV B before the onset of Minimum Perceptible Erythema (MPE). Increased UV B will elicit, however, an increased melonogenic effect ultimately leading to a darker appearing skin. Previously, un-tanned skin will be more susceptible to UV B induced erythema and therefore UV B levels should be minimized in the early portion of an indoor tanning program.
Because of the factors mentioned above it is necessary in a commercial indoor tanning application or in the consumer tanning products marketplace to offer sunlamp products which are appropriate to the range of "tannable" skin types and skin conditions. This means that sunlamp product manufacturers, to be fully competitive, must offer products which produce the radiative characteristics necessary for safe and effective tanning of a range of skin types and conditions.
To this end many manufacturers offer a variety of ultraviolet sources which when used in conjunction with their tanning equipment give the desired ranges of UV A and UV B appropriate for the person(s) undergoing the tanning process. To cover the range of ultraviolet lamps to meet the needs of the market, equipment manufacturers and distributors generally make available three separate groups of lamps having the following characteristics:
1. Lamps with a relatively low proportion of UV B radiation approximately 1% UV B/UV A and lower,
2. Lamps with an intermediate proportion of UV B; approximately 1.0-3.0% UV B/UV A, and
3. Lamps with a relatively high proportion of UV B; 3% and above, usually to 5% maximum.
In all cases, UV A is defined [by the US FDA] as the region of 320 nm -400 nm, [and] UV B is defined as the region of 260 nm-320 nm.
How does a sun-tanning lamp differ from one used to make rocks and minerals fluoresce?
The tubes/lamps/bulbs used for rock collecting usually have a relatively narrow band of UV emission and they do not generally use the same blend of phosphors as the sun tanning lamps do. A sun tanning lamp is regulated by the FDA to emit no more than 5% UV B and the rest is UV A. This has usually been accomplished by use of a UV A phosphor (Philips color /09N) that has a peak wavelength at 352 nm because the shape of the emission curve shows that the phosphor emits about 5% in the UV B region of the spectrum. The lamp manufacturers have stopped making the 9 watt version with the 352 nm phosphor. It is still available in the 36 watt size lamp. The fluorescent response of many minerals can be very specific to the wavelength. For example, some calcite from Mexico fluoresces three different colors depending on the wavelength to which it is exposed. This calcite fluoresces a bright blue-white under UV C radiation with a peak of 254 nm, yellow under some UV B tubes/lamps with a peak around 315 nm, yellow under UV A with a peak of 352 nm, and hot pink under UV A with a peak of 368 nm. The best yellow response appears to be with the Nichia UV B phosphor. A relatively small number of other minerals also exhibit a different response to various UV wavelengths, so mineral collectors prefer UV tubes/lamps with relatively narrow emission bands.
How does UV C disable micro-organisms?
More than 100 years ago, scientists realized that some components of strong sunlight were capable of disinfecting and sterilizing items by killing micro-organisms (such as bacteria, spores, molds and viruses). One such portion of the electromagnetic spectrum was identified as being ultraviolet radiation of wavelengths between 200 nanometers (nm) and 300 nanometers. The region of ultraviolet radiation is often called UV C, short-wave UV, or germicidal UV. WayTooCool began offering a line of UV Sterilization/germicidal lamps in mid-2020.
The DNA in most life forms is double stranded with hydrogen bonds connecting parts between the two strands. When micro-organisms are exposed to UV C radiation, the energy is absorbed in the hydrogen bonds in the DNA, causing some of the bonds to rupture and also causing portions of the DNA to fuse.
This disruption of the DNA chain prevents the cell from replicating and the micro-organism ceases to grow. The DNA disruption is well known and many studies have been done to determine the amount of UV C needed to kill particular micro-organisms. In very general terms, the more complicated the micro-organism is, the more UV will be required to kill it. For instance, the simplest bacteria usually have only a cell wall with the DNA inside, so they are easy to kill. Yeasts have the cell wall, plus a cell nucleus, with the DNA inside the nucleus, so more UV is needed to kill yeasts. Fungi have all of those parts, and also contain pigments so even more UV is required to kill them than for the simpler micro-organisms.
The UV dose is the product of the intensity of the UV and the amount of time. Although in mathematical terms, a small amount of UV for a long period of time can equal the same dose as a large amount of UV in a short time, there is some evidence that a high dose in a small amount of time kills more micro-organisms than the reverse. The dose of UV is often given in terms of micro watt seconds per centimeter squared. The relationship between the dose of UV and the deactivation rate of microorganisms is a log scale. An important concept is called the D10 value, which is defined as the UV dose needed to deactivate 90% of any given micro-organism. If the D10 value is 500 micro watt seconds per centimeter squared (micro watt s/cm2), then to deactivate 99% will require 1000 micro watt s/cm2, to deactivate 99.9% will require 2,000 micro watt s/cm2.
Table A shows the dose in micro watt seconds per centimeter squared required to kill 99.9% of various micro-organisms.
| TABLE A | |
|---|---|
| Bacteria | |
| Bacillus anthracis | 8,500 |
| Legionella dumoffil | 5,500 |
| Mycobaterium tuberculosis | 10,000 |
| Clostridium Tetani | 22,000 |
| Sarcina Lutea | 26,400 |
| Yeast | |
| Baker's yeast | 8,800 |
| Brewer's yeast | 6,600 |
| Common yeast cake | 13,200 |
| Mold | |
| Penicillum expensum | 22,000 |
| Penicillum roqueforti | 26,400 |
| Algae | |
| Chlorella vulgaris | 22,000 |
| Viruses | |
| Bacteriophage (E. col) | 6,600 |
| Hepatitis virus | 8,000 |
| Influenza virus | 6,600 |
Using data of this nature and given the UV output of a particular UV C tube/lamp, we can figure out the amount of time needed to deactivate 99.9% of any particular micro-organism. For example, if we choose the mold Penicillum roqueforti (one of the most UV resistant molds), and a single UV C tube/lamp that emits 340 micro watts per centimeter squared at one meter, then at 1 meter, the time required to kill 99.9% of the Penicillum roqueforti is calculated by the formula: [26,400 micro watt seconds per centimeter squared] divided by [340 micro watts per centimeter] which equals [77.65 seconds].
If the UV dose is doubled by adding a second tube/lamp, the time reduces to 38.8 seconds, and for the use of four lamps, the time reduces to 9.7 seconds. In practical terms, this means if we want to be able to kill 99.9% of even the toughest micro-organisms in 10 seconds, then we simply calculate the number of UV C lamps that will be required to supply the proper dose and an apparatus can be designed accordingly.
Bulbs/tubes/lamps?
What is the proper name for the bulb? The people who actually manufacture the bulbs call them lamps or tubes. The general public most commonly refers to them as bulbs. The concept of calling the bulb by the name "lamp" confuses people because the general public also refers to the whole lamp fixture as a lamp. As far as I am concerned, the UV source can be called a bulb, a lamp, or a tube — as far as the general public is concerned it really does not matter. If you need a replacement bulb/lamp/tube for one of my lamp fixtures, I do not care what you call it, all I need to know is the wattage, the wavelength (SW/UV C, MW/UV B, or LW/UV A), and if it is powered from AC or DC.
I use compact fluorescent "H" tubes or "U" tubes because the "side by side" shape allows the bulbs/tubes to emit about twice as much UV per foot compared to straight tubes.
UV bulb H-shaped tubes
For the small units, I standardized on 9 watt bulbs/tubes with a two pin G23 base because Philips makes those bulbs/tubes in all three wavelengths — UV A, UV B, and UV C. In fact, Philips is the only major supplier I have found with standard commercially available "H" tubes in all three wavelengths, and Philips only makes them in the 9 watt size and the 36 watt size. I occasionally use a 9 watt UV A bulb manufactured by Radium when the Philips ones are out of stock. I also use Philips 18 watt UV A and UV C lamps/tubes, 36 watt UV C, 60 watt UV C and 95 watt UV C lamps/tubes.
Philips does not manufacture all of the sizes and wavelengths that are needed for fluorescent rock collecting. The larger UV A and UV B lamps are simply not available from Philips, so I use other sources for some of the 18 watt, 36 watt and 60 watt UV A and UV B tubes.
How does the wattage of the tube/bulb compare to UV output?
The design of the lamp fixture can make large variations in the amount of UV that a lamp fixture emits — even for fixtures using the same tube/bulb. The size of the filter glass, the shape of the reflector, the material the reflector is made from, the kind of filter glass, hours of use of the lamp, and the internal temperature of the lamp fixture all have major effects on the final output of the lamp fixture. There has been some independent testing of various brands of UV lamps. The information gets complicated and I will devote another section to those details. For this information, I want to stick with easily referenced values, so I will use the values that are published by Philips.
According to the Philips catalog at 100 hours of use:
a 4 watt tube/bulb emits a total of 0.9 watts of UV C (SW)
a 9 watt tube/bulb emits 2.4 watts (overdriving them with a 13 watt ballast, causes them to emit about 3.2 watts)
a 15 watt tube/bulb emits a total of 4.7 watts of UV C
a 18 watt tube/bulb emits a total of 5.5 watts of UV C
a 25 watt tube/bulb emits a total of 7.0 watts of UV C
a 35 watt high output tube/lamp emits a total of 12 watts of UV C
a 36 watt tube/bulb emits a total of 12 watts of UV C
a 60 watt high output tube/bulb emits a total of18 watts of UV C , and
a 95 watt high output tube/bulb emits 32 watts of UV C
How long will a tube/lamp last?
I am currently conducting life-cycle testing on some of the lamps/tubes that I use. The answer to this question depends on many factors. Here is a link to a website with pertinent information: http://www.zetatalk.com/energy/tengy07q.htm.
Philips has done extensive testing on all of their products but the test conditions do not match the way rock collectors use these lamps/tubes. On my larger AC models (18 watts and above), I use special programmed start ballasts that will allow the lamps/tubes to be cycled on and off for at least 50,000 cycles before burning out when properly maintained. One condition that will drastically shorten the life of the tube and the ballast is if the fan filter media gets clogged causing the unit to overheat.
What are phosphors?
The white powder in a standard household 4-foot fluorescent tube is a phosphor or blend of phosphors. The mercury vapor inside the tube emits SW UV and the phosphors absorb the UV and re-emit it (it fluoresces) to produce white light. The mercury vapor in a SW UV bulb emits light radiation at a wavelength of about 254 nm.
To make a fluorescent tube emit any other wavelength (including white light), the common method is to put a phosphor coating on the inside of the tube. There are two phosphors commonly used in the LW (UV A), "poster lamps" or "black lights" - one phosphor that emits a peak wavelength at 352 nm and one that peaks at 368nm. For more information, please view the article "Long Wave Ultraviolet Sources for Mineral Collectors" (PDF) by Don Newsome. Generally, the 368 nm gives a better LW response from the minerals. The Philips 9 watt UV A bulb uses the 368 nm phosphor (Philips color /10) ), and the Philips UV B bulb is available in narrow band UV B (Philips color /01)and wid eband UV B (Philips color /12). The Philips UV C bulb is of course 254 nm. The Philips 18 watt bulbs are available in UV C and UV A (color /10).
Philips UV A 36 watt bulb is available with a phosphor with a peak at about 352 nm (Philips color /09N or in the phosphor with a peak at 368 nm (Philips color /10). UV B tubes use a variety of phosphors depending on the manufacturer and they all have peaks somewhere between 302 nm and 318 nm.
Are the phosphors always inside the bulb?
No, to my knowledge, several manufacturers of UV lamp fixtures, are selling or experimenting with wavelength changing materials that are external to the tube/bulb. I have a US Patent (and several more Patents Pending) on lamp fixtures with various wavelength changing mechanisms. UVP Inc., has several US Patents, and UV Systems has at least one Patent. I was manufacturing several models that have a single UV C tube/bulb and a manual or motorized rotating element that changes the UV C to UV A and UV B. AS the element is rotated, the UV automatically and continuously changes from UV C, to a blend of UV C & UV B, then to all UV B, then to a blend of UV B & UV A, then all UV A, then to a blend of UV A & UV C. The effect in a display case is captivating. I find that people generally watch one specimen as the UV changes, then they watch another specimen go through all of the UV changes, and another, and another, etc.
Why would I want a lamp fixture with UV B?
Some of the minerals fluoresce a different color under UV B than they do when exposed to other wavelengths of UV. For example, some of the tugtupite from Greenland fluoresces three colors — from a pink, to a salmon, to an orange depending on the wavelength of the UV that is shining on the specimen. Some calcite from Challenger Cave, near Monterray, Mexico, fluoresces a bright blue-white under UV C, yellow under UV B (and 352 nm UV A), and hot pink under 368 nm UV A. All scheelite fluoresces a bright blue-white under UV C, but some scheelite specimens also fluoresce pink, blue or yellow under UV B. In general, calcites from Arizona are particularly nice under UV B and often a different hue than while under SW. The calcite and fluorite from the Hull mine in Arizona fluoresces best under UV B. The material from my Purple Passion mine and my Hogan Claim (both in AZ) also exhibits a nice color change as the wavelengths change. Under UV C, the calcite fluoresces several shades of red and pink, the willemite fluoresces green or yellow-green, some of the fluorite fluoresces blue or purple, and the aragonite fluoresces a blue white or a cream. No matter what shade of red or pink the calcite fluoresced under SW —it all changes to a scarlet color under UV B, additionally under the UV B, all of the fluorite fluoresces and some of the aragonite fluoresces. Under UV A only the fluorite and some of the aragonite or caliche fluoresces.
What about fans?
Having fans to keep the lamp fixtures the proper temperature are essential in some models. The problem with using the small 9 watt field lamps as the UV source in a display cabinet or in an application requiring the lamp to be on for long periods of time is the build up of heat. If the unit is going to be on for long periods of time, having a fan is absolutely essential to circulate cooling air for preventing the ballast from overheating from the heat generated by the bulb and also to maximize the amount of UV that is emitted.
I do install fans as a standard feature in all of the lamp fixtures. All of the fans I currently use operate on 12 volt DC. For the DC fixtures, no additional power supply is needed because the 12 volt power supply will operate both the fan and the bulb(s). For the AC versions, I install an internal 12 volt power supply to run the fan. In the larger lamp fixtures, am currently using a 12 volt power supply that runs on any power from 100 volts to 240 volts and from 47 to 63 hertz. In the smaller units, I still use 110 volt AC 12 volt power supplies.
Lyman Hays, an electrical engineer, did independent testing of various lamp fixtures and reported his findings in the UV Waves (the newsletter of the Fluorescent Mineral Society (FMS) http://www.uvminerals.org. Of particular interest is Lyman's statement: "In my earlier discussion, I observed the Way Too Cool 95 Watt light is the brightest of those tested. According to Figure 2, its peak irradiance is about 11% higher than that of the next brightest light, the TripleBright II. Measurements for Figure 2 were made after the lights were on long enough for their internal air temperatures to stabilize. If instead comparison is made using the highest irradiance values reached as the lights warmed, then the Way Too Cool 95 W reached peak irradiance 43% higher than did the TripleBright II. This example serves to illustrate the importance of temperature control."
As a direct result of Lyman's testing, I have added much more cooling to the 95 watt lamps (and to many of the other display units). On the 95 triple units, I use TWO centrifugal blowers rated at about 40 CFM each - pulling air into the unit and axial fans pushing air out of the unit. This provides much more cooling air flow and as a result, the UV output is greatly increased. Using two fans in a "push me, pull you" configuration does not double the air flow, but it does increase it by up to 50%.
The 60 watt bulbs/tubes require a pretty strong cooling air flow as they were designed to be in HVAC ducts with air flow past them. The only time I would not run the fan is if I were outside running the lamp under cold conditions. DO NOT LOOK AT THE OUTPUT of the lamp unless you have some sort of eye protection - even cheap plastic safety glasses allow you to actually look right at the filter.
How can you tell if the bulb is too hot or too cold?
DO NOT LOOK AT THE BULB UNLESS YOU HAVE UV BLOCKING GLASSES ON.
The SW filter glass always looks redder than LW glass because the Hoya glass does allow a little red light to come through. However, when the bulb is either too cold or too hot, the filter glass and the bulb will appear redder than when it is at a good temperature. When you first turn the lamp on, it will take a few minutes for the temperature to stabilize. As it warms up, the color will shift a little. Normally, the SW filter will look a nice purple and the LW filter will look a nice blue. If the bulbs are too hot OR too cold, the UV output changes and the color shifts so that the SW bulb looks much more reddish. I was out collecting one time when it got down to nearly freezing and the lamp did not have a switch to turn the fan off, so it looked really reddish and the UV was way down.
Ballasts
Do both the 9 watt AC 110V and DC 12V lamps run in "overdrive" (i.e. 13 watt ballast) or is it just the DC unit?
Both the AC and the DC versions are overdriven with 13 watt ballasts. The 9 watt units use an "instant start ballast", which is the roughest on the bulbs for turning them on and off because they get the full power right away and each time a little of the coating on the filament gets burned off. I overdrive all of the 9 watt bulbs with 13 watt ballasts because it produces almost 50% more UV. With a standard 9 watt ballast, Philips rates their 9 watt bulbs for a lifetime of about 3,300 on/off cycles. The 13 watt ballasts are slightly harder on the filament, so we estimate about 3,000 on/off cycles. I do have a few of the 13 watt ballasts that will operate on 240 volts 50 hertz. The 240 volt ballasts are not a stock item here in the USA, however, one of the major manufacturers does custom make them at three times the cost of the 115 volt versions. The 230 volt, 9 watt ballasts are bigger than the 110 volt versions and I cannot fit three of them into the enclosure, so I cannot make a three wavelength model that will plug directly into 230. For these reasons, I recommend using the DC models with a universal 12 volt power supply in countries that have 230 volt AC power.
As it stands now, I am limited to instant start ballasts on the 9 watt bulbs because the available lamps/tubes only have two connections exposed — i.e. two pin bulbs. I am working on getting bulbs with 4 pins instead of 2 pins. That would allow me to use more friendly ballasts and to extend the life well beyond the 3,000 on/off cycles. So far, I have not found the bulbs in that style, but I am looking.
Because the big display lamps are commonly placed inside or on top of a display case, I can put the switches on the power cord, for a slight extra fee. I use a small project box to hold the switches and I run a cord with multiple pairs of wires between the switch box and the lamp. Also, for all of the bigger bulbs/tubes, the ballasts I use are programmed start ballasts - when first powered up, the ballast sends a small amount of power to warm up the filament, then it increases the voltage until the bulbs "fires", then it ramps up the power until the lamp is at full power. The whole process takes 1 to 2 seconds, but it means you can turn the bulbs on and off up to 50,000 cycles before burning out the filaments.
For the bigger lamp fixtures, the ballasts I am using are called "programmed ballasts". Whenever power is applied, the ballast sends a specific amount of power to warm up the filament of the bulb/tube, then the ballast starts raising the voltage until the bulb/tube lights up (when the voltage drops due to the ionization of the gas), and then the ballast raises the current until the bulb/tube is at full power. The entire process takes a second or two every time the bulb is turned on. I spoke with the Electrical Engineer who designed the ballast and he said it was designed to be able to cycle a Philips bulb on and off for at least 50,000 cycles without burning up the filament. If you will be cycling the bulb on and off, this becomes important to you.
Why do we need filter glass?
All of the easily available UV sources emit white light along with the UV. This white light interferes with looking at the fluorescent colors and it makes the colors look "washed out" or faded. The filter glass blocks the white light while letting the majority of the UV pass through the filter. The best SW filter glass available is made by Hoya of Japan. However, transmitting SW UV is not easy. Hoya glass will only transmit about 64% of the SW UV when the glass is new. As the glass is exposed to long term UV C, the UV C transmission decreases until the filter eventually needs to be replaced. The LW glass on the other hand passes about 85% of the LW UV and never needs replacing.
Can the long wave tube be substituted for a medium wave tube at a later time? Are the lamps tuned to work with only a SW/LW combination?
The SW bulb has Hoya SW filter glass. The LW bulb has the much less expensive LW filter glass. The LW filter glass will only pass about 60% of the MW, while the SW glass will pass about 90%. You could switch the SW bulb with a MW bulb, but I do not think you would be happy with the MW bulb behind the LW glass. However, I can make the lamps with any combination of parts. The SW glass WILL work with the either the LW OR the MW bulb, so it is possible to use TWO pieces of SW glass in building a lamp fixture, but it adds to the cost because of the difference in the cost of the SW glass vs. the LW glass.
How big a display case will a lamp fixture light up?
In the world of fluorescent minerals, more UV power is better. If the very powerful lamps are out of your price range, you will want to use a smaller case. The 9 watt units will work with a small display case — up to a 1 foot cube or so — but you will want a unit with a fan if the lamp fixture will be on for long periods of time. The 9 watt units are OK at about 1/4 to 1/3 of a meter high with a spread of about 1/3 of a meter.
A 36 watt SW (UV C) lamp fixture will light a standard case that is 2' tall x 2' deep x 4' wide, BUT the minerals at both end of the case will not be lit well so you would need specimens that fluoresce brightly at the ends. According to Philps a 36 watt tube/bulb emits 12 watts of UV C
A 60 watt SW lamp fixture will light a standard (2'x2'x4') case fairly well and will reach out to the ends, but it will not be bright if you raise the lamp much higher than a standard 2' tall case. A 60 watt bulb emits 18 watts of UV C.
A 95 watt SW will do a good job in a 5 foot tall case if the specimens at the bottom fluoresce well. A 95 watt bulb emits 32 watts of UV C. I also make a unit with a 95 watt SW and a 65 watt (or a 60 watt) LW bulb.
A 120 watt SW unit has two 60 watt bulbs so it emits 36 watts of UV — a bit more than a 95 watt unit.
A 190 watt SW unit has two 95 watt bulbs so it emits 64 watts of UV C. The Franklin Mineral Museum in New Jersey recently revamped their 28' long display with 8 of the 190 watt SW units.
As for dual units, to my eye, a unit with 36 watt SW and 36 watt LW always seemed a little miss-matched on response in a group of mixed SW and LW fluorescent minerals. The LW minerals seem brighter to me than the SW minerals - yes, the LW minerals. To my eye, the 60 watt SW/ 36 watt LW combination gives a very good blend of SW and LW. I think the answer lies with the filter glass. The best SW filter glass available is made by Hoya of Japan. However, transmitting SW UV is not easy. Hoya glass will transmit about 64% of the SW UV when the glass is new.
As the Hoya glass is exposed to UV C radiation for long periods of time, the UV transmission decreases until it eventually needs to be replaced. The LW glass on the other hand passes about 85% of the LW UV and never wears out. Now let's look at some realistic numbers. According to Philips, a 36 watt LW tube emits a total of 9 watts of UV A and a 36 watt SW tube emits a total of 12 watts of UV C. Not all of the total UV energy will be directed out through the filter glass, but we can use the numbers that Philips provides for a relative comparison value because the two lamp fixtures are of the same design. If you crunch the numbers, 64% of 12 watts (for the UV C tube and filter combination) is almost exactly the same as 80% of 9 watts (for the UV A tube and filter combination). They both end up with about 7 watts of UV available.
Battery Power
The 9 watt models (with the 13 watt ballasts) use about 1 amp for each bulb that is turned on. The common lead acid battery packs are usually 7 or 8 amp-hours. For a triple unit with all three 9 watt bulbs on, an 8 amp-hour battery will last for approximately 2.5 hours of use and there is not any quick and easy way to recharge the smaller batteries while out in the field. Harbor Freight Tools sells a "jump start battery" system with a 17 amp hour battery, a built in charge, white light, and a volt meter. The normal price is $59 and it goes on sale regularly for $39.
12 VOLT POWER PACK WITH JUMP STARTER. Harbor Freight also sells a jump start battery with a 12 amp-hour Lithium iron phosphate battery. Link: LITHIUM ION JUMP STARTER AND POWER PACK.
For a useful comparison, I had a 36 watt SW unit in the field all night using the 17 amp-hour battery unit. I ran the unit from about 5 PM to about 1 AM, then again from 2 AM to about 4:30 AM. Of course, the more bulbs/tubes that are on, the more power is used. One big advantage to the "jump start" units is that you can hook up the battery cables and reverse feed power from your car battery to the unit to get a fast recharge on the jump start battery while actually out collecting. The really nice thing about a 36 watt unit, is that it is a good size to be used with a display case at home AND also out in the field.
Microscope lamps
I have made a lamp fixture for use with a stereo microscope. The current version is custom manufactured with two 9 watt bulbs positioned side by side for a higher energy density. These UV A tubes/lamps emit a wavelength of 368 nm because that is a good wavelength to make the hydrocarbons fluoresce. Approximately a dozen of these lamp fixtures are currently being used by petroleum geologists to quantify information about oil samples. Apparently, the color of the fluorescence (ranging from white to a dark yellow), identifies the composition of the oil/wax while the color density distribution tells them the relative ratio of oil to rock. I make a simple plastic/acrylic stand to hold the lamp in place at about a 45 degree angle shining down onto the microscope stage. The stand is removable so that the lamp unit can also be used as a hand held device. I expect these will be replaced by the LED Flashlights as time goes on.
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