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Author: Subject: One way gas release needed
BromicAcid
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One way gas release needed

What I need is something I can use to allow gas to escape but no gasses to enter. Currently I have a funnel with a metal ball bearing in it with a screen over the top, pressure increases, ball bearing pops out of the hole, gas escapes and ball rolls around until the pressure drops then the ball rolls back into the hole blocking it till the pressure shoots it out again. But this is inefficient and allows too much gas to reenter the system before locking it off again, and the seal is not too good and there are other problems.

So, is there some available item that might be substituted for my rigged up contraption, I'm sure there is, the only prerequisite is that it must be able to handle gasses at somewhat elevated temperatures, 500 C area.

[Edited on 1/15/2004 by BromicAcid]

Shamelessly plugging my attempts at writing fiction: http://www.robvincent.org
Haggis
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The easiest way of doing what you're talking about is called an airlock and is used in home alcohol making. What it involves is a tube from the container evolving gas, bubbled through a liquid. The bubbles escape, but no atmospheric oxygen can get back in to spoil the reaction because the hose is under level of the liquid. Water is commonly used, but others could be used in place of it.

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I am a fish
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If you use an airlock to vent a system at elevated temperatures, put a buffer flask between the reaction vessel and the airlock. Otherwise when the reaction vessel cools, the gas within will contract, sucking the liquid into it.

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Hermes_Trismegistus
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Use a "gasket maker" from the automotive department to improve the seal on your apparatus. It's really high tech and the different varieties have their max temperatures listed as well as being fairly chemically resistant (combustion byproducts, coolants, synthetic oil substitutes). They put hundreds of millions into research to come up with the stuff, by all means use it!

I am gonna keep your device in mind when I need one.

Those fermentation locks only provide a very small amount of negative resistance, just enough to prevent drawback from changing barometric pressures. As a backup you are supposed to fill them with a metabisulphite sterilizing sol'n if (when) they fail.
unionised
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Using a long length of tubing to a bucket of water is the cheap way.
Hermes_Trismegistus
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Are you really sure you want to save that particular ten bucks?

Yes....and risky, if you really get suckback you'll end up with water in your reaction vessel. At about 500 degrees h20 will turn poor BromicAcid's vessel into a bomb and whatever room he is in into a broiling hell.

I hear superheated steam scaldings suck, they say it takes you days to die and infection is almost 100%....and anything over 70% surface area is 100%fatal.

Of course, I am not sure I would want to survive, at the rehab hospital I was in we all felt creepy going past the burn unit.

They would make such horrible sounds. The nurses would do this thing called debridement....Basically they would scrub the tissue with a nylon bristled brush until the infected tissue was all scrubbed off. Every day, they had some very strong sad looking guys walk around from room to room holding them down while a bitter-faced old nurse went to work.

They would select the rooms at random to try to be a little more humane. I was told that the anticipation was almost as bad as the dressing changes (debridement) sessions themselves, but only by the nurses. The victims never talked much at all, and we didn't ask alot of questions.

I asked why they didn't use an anesthetic and I was told that almost all topical painkillers severly reduce bloodflow to the skin and they couldn't allow that, Something about it being a race against time to get them a to grow a new layer of skin that would prevent infection and death. The painkillers that didn't reduce bloodflow affected overall body temperature and they didn't have any skin so they couldn't thermoregulate.

I remember them chasing this young black girl around (I could tell from the small patches of hair still on her head, her skin was all white because of the exposed body fat) , then they held her down and strapped this clear plastic face-thing onto her flesh face. Apparently it squished the tissue into place so it would take the form of the clear acrylic mold, I don't know why the bothered really, its not like she had a nose or ears or anything. Why torture her more?

I was just too freaked out to say anything though, I was only on thier floor to watch their t.v., old ladies were watching "Wheel of Fortune" on my floor. I didn't want to watch tv anymore after that. I felt like puking. Instead I went outside and chain smoked for about two hours, and when that didn't cut it I wheeled my chair across the street to the park and got high.

One thing about the burn unit patients was they tended to keep them locked away. Apparently suicide attempts were epidemic, and not those sissy "13-year-old-teenage-girl-taking-a-dozen-tylenols-cuz-her-thighs-are-too-fat-and-billy-doesn't-want-to-take-her-to-the-prom" suicide attempts. These guys/girls/little kids jumped off the balcony, cut their throats, and tried to ram screwdrivers/pens/pencils into their hearts. It still throws a chill through me to imagine that children less than ten years old were trying to find a way to kill themselves.

Poor sons of bitches.

I would go with the tablespoon of putty. Because I seem to remember that a tablespoon of water turns into like 40 litres of superheated steam at 500 degrees.

anyway, its up to you.....

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Organikum
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I agree with water being a rather bad idea.

A spring loaded ball valve from industrial supply (hydraulics, automotive...) is the way to go. The material strongly depends on the gases you want to process - there is no universal material at those high temperatures.

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Blind Angel
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I recall reading something in the Organicum about that (i don't know if it's exactly what you want).

Take a plastic tube, block one of the end and make a little incision on the side of the tube, gaz will be able to go out but when it will try to enter the pression will close the hole.

Schema:

()¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯<s>¯¯</s>¯) <= This end close

I think that the name is a bunsen valve or something like that

/}/_//|//) /-\\/|//¬/=/_
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 Sciencemadness Discussion Board » Fundamentals » Reagents and Apparatus Acquisition » One way gas release needed Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues