Gallery of Lights
Lamps => Modern => Topic started by: dor123 on August 22, 2011, 01:30:44 PM
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There is a slight differences on the gas filling of the american energy saving T8s and their european counterparts, in the fact that the american T8s, have more krypton in the argon-krypton penning mixture than the european T8s, but this isn't the official reason.
The real reason is: The american energy saving T8s (F32T8) have an electrically conducting coating between the phosphors and the glass, which considerably reduces the ignition voltage of these lamps (Probably even below the ignition voltage of the "Pure argon" T12s), so these lamps can be operated on rapidstarts, despite the presence of krypton (Even more krypton than the european T8s).
The reason why the european T8s, didn't adopted this coating is because the rapidstart/starterless ballasts in Europe, was very rare and most of the ballasts there are preheaters.
Thanks Max for this information! I was needed it so much! :).
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The conductive coating technique is also used with 34W energy-saving T12 lamps. Although I didn't know it was used to allow the use of a higher krypton content in the F32T8 lamps! Come to think of it, that's a pretty clever idea!
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The F32T8 RS ballasts also had a higher OCV than the F40T12 RS ballasts too.
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The conductive coating technique is also used with 34W energy-saving T12 lamps. Although I didn't know it was used to allow the use of a higher krypton content in the F32T8 lamps! Come to think of it, that's a pretty clever idea!
Vince: The idea of using krypton, was to use only krypton as an alternative to argon. However, because its higher ignition voltage, 25% of the argon was remained to facilitate starting, but the european T8s still limited to preheat or electronic ballast, so the american added this conductive coating to their T8s, and so could use more krypton and still get even lower starting voltage than T12 with pure argon.
And as Joseph stated the F32T8 rapidstarts have a higher OCV than the F40T12 rapidstarts (But i still think that the conductive coating is the primery reason).
I think that the american F34T12, have also krypton, if they have also this conductive coating, and therefore have lower wattage (And light output) than F40T12, as it remained in T12 format and krypton have lower arc voltage.
Because of this the F34T12 seems to be similar in some ways, to the british 8ft 100W energy saving T12, which have also lower wattage (And light output) than the original 8ft 125W T12, because it remained as T12 and not reduced to T8.
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And as Joseph stated the F32T8 rapidstarts have a higher OCV than the F40T12 rapidstarts (But i still think that the conductive coating is the primery reason).
Actually I wouldn't say that Dor, I believe both the higher OCV and the conductive coating both play an equal role in starting the F32T8 lamp, this is especially true in the case of the 30, 28, and 25w energy saver T8 lamps where the product literature recommends the use of a ballast with an OCV of 550v or higher.