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  1. #181
    holmburgers's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    The filter paper is flat and is measured in diameter. You custom flute or fold it to meet your conditions such as funnel size or flow rate.

    PE
    I suspect that Shaz means filter-pore size, such as in microns (or whatever).
    If you are the big tree, we are the small axe

  2. #182
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    I was just flipping through this and fyi for anybody thinking about it - autoignition temp is WAY differerent than the flash point or the fire point of the liquid. Very quickly:

    Flash point - temp at which the vapors already present would flash but not sustain a flame.
    Fire point - temp at which a liquid, once it saw an ignition source, was high enough to produce sufficient vapors to continue burning
    Auto Ignition temp - literally spontaneous combustion, no ignition source is required.

    For toluene
    FLAMMABLE PROPERTIES:
    FLASH POINT: 40F (4C)
    AUTOIGNITION TEMPERATURE: 896F (480C)
    OSHA/NFPA FLAMMABILITY CLASS: 1B (flammable liquid)
    LOWER EXPLOSIVE LIMIT (%): 1.2%
    UPPER EXPLOSIVE LIMIT (%): 7.1%
    FIRE AND EXPLOSION HAZARDS
    Vapors may be ignited rapidly when exposed to heat, spark, open flame or other source of ignition.
    Flowing product may be ignited by self-generated static electricity. When mixed with air and exposed to
    an ignition source, flammable vapors can burn in the open or explode in confined spaces. Being heavier
    than air, vapors may travel long distances to an ignition source and flash back. Runoff to sewer may
    cause fire or explosion hazard.

    Personally, I wouldn't work with the shite anywhere inside my house. Think it of like working with gasoline in your basement - yikes!
    Last edited by nhemann; 05-02-2011 at 04:48 PM. Click to view previous post history. Reason: my poor grammar
    "There is no such thing as objective reality in a photograph"

    My flickr and (gasp!) dpug photos - take a look if you like.

  3. #183
    Photo Engineer's Avatar
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    The information in post 182 is correct.

    Unfortunately, one thing is omitted. Once the material flashes, the flame formed is high enough in temperature to sustain a fire if enough vapor is present, and that is the big concern here, especially with EtOAc (Ethyl Acetate). It is so volatile that enough vapor can be present to sustain a minor (or major) explosion. BTDT!

    PE

  4. #184

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    Consider a 2 cubic meter room. 2 cubic meters are equal to 2000 liters. Two percent of 2000 liters is 40 liters. He would have to evaporate 40 liters of ethyl acetate for it reach 2% of air concentration. He would have to work in a very small room or with very large amounts for it to be actually dangerous.
    Even if his room is full of stuff and air cannot escape or enter it, he still needs to have evaporated at least 20 liters of ethyl acetate for it to be dangerous. I'd say a 2 cubic meter room is a below average small room

    I can't remember how large the bottles he own are exactly, but they are definitely below 5 liters, more like two liters maybe. (http://d30.e-loader.net/0g0K012Peu.JPG for reference.) Unless his 100W lightbulb can reach 860 degrees fahrenheit, three times as much as the 60W lightbulb in your link. 2% air concentration is a lot.

    Even the 1.2% air concentration for toluene he needs to evaporate 24 liters of it in 2m^3 of air. Only 12 liters of it in 1m^3 is still at least four times as much toluene as he owns, all evaporated into the air. He needs to work with MUCH larger amounts for it to be actually dangerous. This is only relevant for large scale lab chemistry.

    He simply does not own enough for it to be dangerous at all.

  5. #185

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    This is pointless to discuss anyway, just do it outside and everyone will be happy Shaz. Lets not derail this thread too much.

  6. #186
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    I use Whatman filter papers: http://www.whatman.com/QualitativeFi...ardGrades.aspx

    I can't find my lone remaining box, since I use it so seldom, so I cannot tell you what size pore I use, not that it would mean anything in this case. You select a paper based on he smallest particle you wish to retain! So, if you have 10 micron particles, you need a smaller pore size for the filter if you want to retain them. The smaller the size, the slower the filtration. The slower the filtration the more your solvents will evaporate. If you use suction to speed it, then you get vacuum loss of solvent! And, the solvent goes down the drain too. In that case, you need a filter funnel with a given pore size or a large pore funnel with your selection of filter paper.

    This is the subject of several days instruction in Organic Chem Lab 101.



    PE

  7. #187

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    Anoher possibility for a "glue" would be Venice Turpentine which is a resin that is soluble in alcohol. Canada Balsam is usually dissolved in a hydrophobic solvent such as toluene.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

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  8. #188
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    A) you have no idea what you are talking about right now....you have forgotten about the difference in specfic gravity between a liquid and a gas - which is a factor of about 1000x. I could blow the hatches off a tanker with 40L of gaseous toulene

    Saftey never hurts and its only useless until somebody blows their house up because they didn't understand exactly what was being talked about - but I humbly bow out.
    "There is no such thing as objective reality in a photograph"

    My flickr and (gasp!) dpug photos - take a look if you like.

  9. #189
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    Quote Originally Posted by nhemann View Post
    A) you have no idea what you are talking about right now....you have forgotten about the difference in specfic gravity between a liquid and a gas - which is a factor of about 1000x. I could blow the hatches off a tanker with 40L of gaseous toulene

    Saftey never hurts and its only useless until somebody blows their house up because they didn't understand exactly what was being talked about - but I humbly bow out.
    You are right! But...

    You could probably do it with less considering 1 mole of Toluene = 22.4 L of gas (at STP), and that will react to form several moles of oxidation products at a far higher temperature! One liter is about 10 miles or 224 L of gas without oxidation byproducts or increased temperature. Lets assume it burns to give 7 moles of CO2 and 7 moles of water (no balancing of equation here), then you have formed 14 moles of gas x 10 = 140 moles x 22.4 = ~3200 L of gaseous byproducts at room temp. Add in the temperature increase and those hatches are going to MOVE baby!

    I have seen my share of lab explosions over the years that I worked as a bench chemist and have been in my share. Better safe than sorry.

    PE

  10. #190
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    Ah, Mr. PE, I was contemplating figuring that out just for the fun of it but you beat me to it, sir! lol. Now I'm gonna have to console myself with the number of joules released.
    Also just as a matter of correctness - I mixed my metaphor, tankers don't have hatches, per se. But it would literally rip open a ship like a tin can. But anyway - I let the topic continue.
    NH
    Last edited by nhemann; 05-02-2011 at 04:59 PM. Click to view previous post history. Reason: i just can't type today.
    "There is no such thing as objective reality in a photograph"

    My flickr and (gasp!) dpug photos - take a look if you like.



 

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