Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Peter B on October 06, 2008, 09:50:21 AM
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Hello
I am new here. I come from an aerospace engineering background I joined because I am currently involved in designing a project with a friend. We have run into a little road block with a slight chemistry issue.
We are trying to design our own lighted bubbler tube. The idea is to make something like you see on the front of a juke box or in those bubble lights you see around Christmas time. They are closed, sealed, glass vessels with a light on the bottom that heats the liquid inside enough to make it boil. We want to use this idea as well. We thought of using a small air pump, but that means constantly refilling the tubes, and more noise then we want to put up with. Also a pump uses too much power for our end application.
After doing some research we found out that most juke boxes and bubble lights use methylene chloride (Dichloromethane) which boils at 40 °C. This is our first choice as well but here comes the road block. Doing some more research we found out that methylene chloride will probably melt the acrylic tubing we were going to use to hold it.
We have thought about using glass, but that greatly complicates the manufacturing of our design. Neither of us own the tools or have any experience working glass. At the moment we are currently looking into other clear plastics.
So my question is could someone recommend another liquid? We are looking for something clear, relatively safe, and with a boiling point between room temperature and 50 °C.
Or, could some one recommend a clear plastic that will stand up to methylene chloride?
Your help is greatly appreciated.
-Peter B
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http://puregizmo.com/pdt310127/_cfx_tt25016.shtml
I'm not sure how transparent they are though.
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Not really sure if you would consider flammable substances safe, lol, but acetone is low boiling as are many hydrocarbons (like pentane, etc.).
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I guess it depends on how flammable and where the flash point is. That said acetone is another one we are looking at. The issue with it is its boiling point is a little higher then we were hoping for, that and it often used to remove bonding agents such as epoxy, which would limit our choices for construction.
With a little more research I came across the idea of using household ammonia or ammonium hydroxide, which apparently has a boiling point of about 36 °C. This is actually now my first choice as it easily available at your local super market, and relatively easy to work with. Can anyone confirm the boiling point? Anyone have experience boiling ammonium hydroxide?
This so far seems to be our best bet.
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I don't think the concentrations available at your local supermarket are going to boil at 36C. You'd need about 25 weight percent ammonia:
http://www.airgasspecialtyproducts.com/UserFiles/laroche/PDF/AAPhysical.pdf
And according to wikipedia, typical household products are 5-10 weight percent. In addition, a concentration of 25 weight percent sounds like it would be quite on the basic side, meaning it is likely to wreck some of your parts. Afterall, ammonia is used as a cleaning agent in the household concentration...
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If you don't want to use teflon tubing, how about diethyl ether as your liquid?
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Ammonia is too dangerous IMHO, stinking, irritant, poisonous.
Not sure if diethyl ether will not attack surface of tubing as well.
Perhaps googling for compatibilty of common plastics and organic solvents will yield some tables? Like here (http://books.google.com/books?id=CF_-xp9iKHcC&pg=PT267&lpg=PT267&dq=compatibility+acrylic+dimethyl+chloride&source=web&ots=R-98_AIiX2&sig=4pbdVwECGYNO0jY9AVIN5vauN-w&hl=en&sa=X&oi=book_result&resnum=5&ct=result).
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One thing I should mention, the tubing for now be ridid, as aposed to something flexible.
Thank you for all the good info so far. Would a 25% ammonium hydroxide have a ph level that would make it un-useable for this project?
I did look into the diethyl ether. I think that one is perhaps not a good idea as it is highly flamable.
Some of my research indicated that their are some light weight oils with low boiling points, but I have not been able to find any.
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25% Ammonium hydroxide is ambiguous (nor is the term Ammonium hydroxide proper). But 25% is pretty damn concentrated for ammonia. I do not use much nor do I know the solubility and pKb, but that might even be pushing the boundaries of the most concentrated solution you could possibly have!
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Density table for ammonia are published for solutions up to 40%, which suggests there should be no problem with preparation of such solution. But I don't like the idea, it is stinking and poisonous, so in the case of any leaks you are in troubles.
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I would not recommend diethyl ether. Ethers will form highly explosive peroxides over time. And I agree enahs, as wikipedia said, commercial preparations of aqueous ammonia only approach 25 weight%, so I can't imagine that it is going to be nice to work with.
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I too have come to similar conclusions about any amonia based solutions and have taken that off my list.
Its starting to look like changing tube material might be easier then finding a useable liquid. Methylene chloride or acetone are not ideal, but its sarting to look like the best option as they seem to have fewer side effects.
I found this chart here:
http://www.engineeringtoolbox.com/boiling-points-fluids-gases-d_155.html
Some of the side effects and risks associated with certain fluids are just not worth taking. We are taking on this project mostly just for our own benefit, but I don't poison myself or blow anything up in the process.
The only thing from that table I found that might be worth looking into was freon R-11. The boiling point on that is almost too low, but it seems like it might be safe enough to use. i am trying to find the MSDS on it now.
-Pete
-Pete
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You can find the MSDS by searching for Trichlorofluoromethane for R-11.
I mean, you are talking about safety and such. But I should point out that what is used in commerical products, while not very flammable, is some pretty nasty stuff.
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One thing I read briefly and now cannot find again is R-11 breaks down with exposure to UV. I wonder how this will affect performance.
None of the chemicals that meet the needs of the project seem to be nice to deal with. I guess I am trying find the one with the least number of negatives, which just might be the methylene chloride.
I ran a house painting business for six years. I have seen just how nasty methylene chloride can be first hand. It is a popular ingredient in stuff like 5f5, bix, and other pain removers. Get it on your skin and it burns quite a bit sometimes.
A little painting tip for everyone. Getting paint off screens can be a pain. If you have fiberglass screens on your house a little 5F5 will do the trick and wont hurt or dis-color the fiber glass. Simply spread a very small amount on with an old brush or rag, let it sit for a few minutes and wipe away with a wet rag. An old toothbrush can be useful to gently get into the screen a bit. Fiberglass looks as good as new. Just be careful as this trick will NOT work with aluminum or Gortex screens. As always use these chemicals safely!
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Funny, I know it isn't good for you, but I never found DCM to be particular painful to get on my hands. The only time it ever really burned was if I got it on my hand while wearing gloves and then it would seep through the gloves (note, latex gloves are terrible in terms of keeping DCM out), and get trapped on my skin and unable to evaporate.
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Tetramethylsilane is not bad with a very low boiling point (~25 °C).
Hello
I am new here. I come from an aerospace engineering background I joined because I am currently involved in designing a project with a friend. We have run into a little road block with a slight chemistry issue.
We are trying to design our own lighted bubbler tube. The idea is to make something like you see on the front of a juke box or in those bubble lights you see around Christmas time. They are closed, sealed, glass vessels with a light on the bottom that heats the liquid inside enough to make it boil. We want to use this idea as well. We thought of using a small air pump, but that means constantly refilling the tubes, and more noise then we want to put up with. Also a pump uses too much power for our end application.
After doing some research we found out that most juke boxes and bubble lights use methylene chloride (Dichloromethane) which boils at 40 °C. This is our first choice as well but here comes the road block. Doing some more research we found out that methylene chloride will probably melt the acrylic tubing we were going to use to hold it.
We have thought about using glass, but that greatly complicates the manufacturing of our design. Neither of us own the tools or have any experience working glass. At the moment we are currently looking into other clear plastics.
So my question is could someone recommend another liquid? We are looking for something clear, relatively safe, and with a boiling point between room temperature and 50 °C.
Or, could some one recommend a clear plastic that will stand up to methylene chloride?
Your help is greatly appreciated.
-Peter B
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Funny, I know it isn't good for you, but I never found DCM to be particular painful to get on my hands. The only time it ever really burned was if I got it on my hand while wearing gloves and then it would seep through the gloves (note, latex gloves are terrible in terms of keeping DCM out), and get trapped on my skin and unable to evaporate.
Getting it under your watch or wedding ring can also be particularly painful.
For the OP, if your major concern is the toxicity of the liquid, I believe you will need to pick your liquid, then find tubing that is resistant to that liquid. There are enough different varieties of clear plastic that you will be able to find something that is resistant to virtually anything you might use. If worse comes to worst, you can use glass.
Alkanes might be the easiest option, something like cyclopentane or petroleum ether. Cyclopentane has a flash point of -37, so you certainly don't want sparks around while you're working with it, but that is slightly better than ether at -45, and the autoignition temperature is higher, 360 compared to 165. And cyclopentane doesn't form peroxides.
The lowest MW ester, methyl acetate, is only a little outside your range (bp 57) and is frequently used as a volatile solvent due to its relatively low toxicity. Somewhat more toxic than ethyl acetate but still very low toxicity for an organic compound.
The low molecular weight amines, like t-butylamine or methyl ethylamine fit the right boiling point range, but tend to be more toxic and are still flammable.
The low molecular weight halocarbons would be the least flammable options, and are also relatively non-toxic, but may be of higher environmental concern.
Hope this helps.