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Thread Tools | Display Modes |
#11
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LEDs
Clark wrote:
wrote in : Clark wrote: wrote in oups.com: On Aug 10, 8:40 am, Clark wrote: wrote groups.com: On Aug 9, 5:40 pm, "Hilton" wrote: Hi, Seems like it is a no-brainer (and easy) for pilots to use LEDs in various forms. Why then, do miners not use them? Why do those trapped miners only have a few hours of light available? Heck, the mine companies could buy al cheapo LEDs for nothing and spread them throughout the mine for little to no cost. These are give away items now. One single tiny little LED would be invaluable right about now and last forever. Some things just don't make sense. Hilton Everything that goes into a mine has to pass the explosion proof test requirements. LEDs can pass, but it has to be in a tested design. That adds cost... With low voltage systems it's fairly easy to meet the requirements for hazardous area ops. IIRC anything below 5 volts is considered safe. -- --- there should be a "sig" here- Hide quoted text - - Show quoted text - It's not just voltage. The housing has to be able to contain an explosion inside of it without igniting combustible gases in the surrounding air... That requirement goes away on intrinsically safe devices. -- --- there should be a "sig" here Actually the requirment is that the device be sealed such that explosive gases can't get inside where any sparks from the switch turning the device on and off might ignite them. I don't believe that is correct. Perhaps a mechanical switch might require a seal but it might not on a low voltage system. In general an intrinsically safe device does not require a seal for explosion hazard mitigation. Other factors such as desire to exclude moisture might result in a sealed case. The voltage is irrelevant; sparks are sparks. Have you ever actually seen a flashlight approved for use in explosive environments? They are nothing more than a rubber covered flashlight with rubber seals on everything and a rubber cover over the switch. -- Jim Pennino Remove .spam.sux to reply. |
#12
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LEDs
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