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" Explosion proof" does not necessarily mean there are no sparks inside the
housing. Its pretty difficult to make a high voltage/current switch or relay that does not spark but these are available in explosion proof versions. "Explosion proof" also does not mean these devices are hermetically sealed. For these devices, and some motors, "explosion proof" means operation of the device will not ignite a flammable atmosphere surrounding the device. Since the device is not gas tight there is a flammable atmosphere inside. When the spark occurs a very small explosion/flame is generated but there are no openings in the device that are large enough to permit this flame to escape and ignite the surrounding atmosphere. If you have a bilge blower motor that uses brushes I don't think it would be an explosion proof unit as these are very expensive. To be economical for the average boater, not the Coast Guard, I would think a bilge blower motor would have to use a different electrical design to be explosion proof. If you have a motor with brushes you need to mount it well above the bilge. If you leave your boat unattended for a month and it fills up with gasoline, and you don't check the bilge before switching on the blower, you may still have a bang up problem. "WKensit" wrote in message landnet.com... Rich Hampel wrote: They use AIR (NOT electric) motors in explosion application. You must mean "TENV" .... totaly enclosed/non-vented: For 'hazardous' atmospheres but certainly NOT for explosive atmospheres. Usually ONLY pneumatic motors and controls are used in 'explosive' applications. How do they make industrial electric motors explosion proof? Impossible you say? Obviously you have never seen TEXP motors. Check, for example, the Westinghouse site. Handy if you want to mount a 150HP blower in your canoe. |
In article uixfd.4961$9b.2815@edtnps84,
"Gordon Wedman" wrote: Its pretty difficult to make a high voltage/current switch or relay that does not spark but these are available in explosion proof versions. No, not hard at all. the Big Boys use Mercury Switches when they need to have sparkless DC Switches. The spark is in a sealed Mercury Switch tube, with just the wires coming out. Me who uses Mercury Switches in Intrinsically Safe appliances.... |
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