SW / LW Fluorescent Lamps AC & DC Field and Display Models If you are interested in any of the above models. Please email us at: www@mineraldealer.com and we will be happy to accomodate your needs. *** About the Special Bulbs *** One very strong selling point for the Philips bulbs that this model uses, is that they put out more UV over the life of the bulb than the standard quartz bulbs and they also have much less mercury in them. Philips also uses a different kind of glass so that none of the ozone producing UV gets emitted from the bulb. Most of the standard quartz bulbs do produce ozone. Philips figured out that part of the reason that the standard quartz bulbs lose efficiency is that the mercury gets into the structure of the quartz and changes it so that less UV gets through. Because the mercury absorbs into the glass, the standard quartz bulbs have to put in about 5 times as much mercury, so that there will be enough mercury left at the end of the useful life of the bulb. Philips found that putting a coating of yittrium oxide on the inside of the bulb helps to stop the mercury from getting into the glass. This coating allows the bulb to emit much more UV over the life of the bulb. Tests have shown that at 10,000 hours, the quartz bulbs are emitting only about 53% of the UV that they did when the bulbs were new. The Philips bulbs, on the other hand still emit about 80% of the UV that they started out with. The quartz bulbs do start out with a little more at the beginning since the quartz glass allows about 92% of the UV through, while the boro-silicate glass only allows about 88% of the UV through. The cross over point where the Philips bulb starts outperforming the quartz bulbs is about 2,000 hours, so for the rest of the 8,000 hours of typical use, the Philips bulb produces much more UV than the quartz bulbs.