h a l f b a k e r yCompound disinterest.
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Typical clean rooms designed for electronics manufacture employ industrial strength air filters to remove as many suspended particles as possible. This helps prevent contamination, but the components are still subject to oxidation.
If the room were sealed off and filled with inert helium instead
of oxy-nitrous air, this would greatly reduce undesired chemical reactions. Workers would need their own air supply, but this would be outweighed by not needing expensive filtration equiptment.
This is easier and cheaper than a vacuum as no structural reinforcement is needed, and workers do not need pressurised suits.
This could also have uses in biological clean rooms where oxygen must be regulated.
If someone can find a better category for this, let me know.
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Are you really suggesting that it would be easier to have all the lab guys wear scuba gear while working than it would be to maintain a decent filtration system? This is one of those areas where my lack of experience is matched by my lack of knowledge, but it doesn't sound right to me. |
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"Dr. Jones, does the lab seem to be...rising?" |
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Who wants a job with a suit? I suppose it depends on the perks. |
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Re: category. "Other" seems right to me. |
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"Did you say something Dr. Robinism, or has Mickey Mouse come to visit?" |
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Good: any dust in the helium-air would sink faster than in normal air, making dust that much easier to control. Bad: breathing equipment would be more complex than scuba because in addition to providing oxygen, it would have to carry off the exhaled breath, which contains oxygen (and water). Scuba gear simply vents exhaled breath into the surroundings. Unless exhalations are vented down a tube running down your leg and to the floor, where it is sucked away and filtered. That way, your exhaust hose doesn't have to be attached to anything. So you could have an airtight gas mask having two valves. When you inhale, valve 1 opens, letting in oxygenated air. When you exhale, valve 2 opens, venting breath into the tube that runs down your leg. Get that naughty smile off your face! |
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[-] Cleanrooms need to be free from particles. What you're describing may be an inert room, but not at all a clean room. |
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For anything that doesn't need to be "clean" but just needs to not oxidize, it's commonly just assembled under a nitrogen (N2) exhaust hood (like a gas stove @ home, but blowing N2 up into a top-exhaust). N2 is much cheaper than He. You can have exhaust hoods in clean rooms if you need both. |
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btw: I have actually worked in cleanrooms. |
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Wait just a minute sophocles. Didn't I see you checking out of a Holiday Inn Express this morning? |
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[JungF] - I didn't work in the noble profession of "cleaning rooms", but did work in "cleanrooms". |
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If you wanted a genuinely inert, or very nearly inert, atmosphere that was quite a bit cheaper, why not use argon? Also, use positive pressure to avoid anything entering the room and push particles towards the edges. I think this is more like an operating theatre than a clean room though. |
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The Holiday Inn lounge is pretty inert, but it's no-where near being clean. |
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This seems like a sensible idea to me. Wouldn't eliminate the need to filter the gas entirely, but if everyone had to wear the suits then it might be reduced (I'm thinking along the lines of the biological suits I saw in the film "Outbreak"). As [sophocles] points out however, nitrogen would be cheaper than helium. |
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For an inert atmosphere, most people use nitrogen. If you need something better, you go to argon. Helium may be inert, but it tends to leak out and get into stuff because of its high diffusivity. |
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I think the reason this isn't done is that it's easier to work in a glove box than it is to wear "scuba gear." |
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I'm not so sure about that. I'm quite comfortable in scuba gear, but there's barely enough room for a few flares, some sunglasses, and a couple of maps in my glovebox :-) |
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