People come up with all sorts of ways to heat and cool the ingredients for the 27/3 test, so that it is done at 68 deg F. In my experience, most of these methods are not as stable nor accurate as one would like. Because my company uses this test as an important indicator while we are reacting our fuel (we switch to the more expensive tests after the reaction is done), we researched what would be the most energy-efficient, no-nonsense way to manage this trick. If you want something foolproof, I suggest the following:
It's a reptile incubator. It is thermostatically-controlled, and will heat or cool to get to maintain the desired temperature. Since it's built like a small refrigerator, it is very well insulated, it can be run on 12V sources, and its peak power draw is 50 watts.
We've been using it for a while now, and it has definitely become a very important part of our lab. It's $160, which I admit isn't in everyone's price range, but for what it does, I felt like it was a good deal.
(Now, does anyone want the free 8 quart bag of "glitter grade" vermiculite that came with it?)
That Picture is missing something!!
Where is the celebretory bottle of California red? I personally feel a successful 3/27 should always be followed up with a celebretory toast.
68F is close to the perfect temperature, Um Hum, for the wine that is.
Nice find... just bought one.
Cool. Glad I could help.
I've been using an electronic wine bottle chiller that I picked up off e-bay. Not as good as the incubator, but is cheaper and sure beats the ice water bath.
Those were what I looked at first. Then I looked at far more expensive incubator type things from scientific instrument companies. This was like the perfect middle-ground between the two.
Now, that's a good idea, seeing as how the 3/27 is temperature sensitive, and this would guarentee the right temp.
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Kumar how many times have you saw a beautiful clear and no fallout 3/27 fail for mono di and tri glycerides? I have saw this a few times (although they failed astm by a very small margin) Was just wondering if others have experienced this. What is the more "expensive" test you are using?
If you mean fail on total glycerin, I haven't. There have been a few times when we thought that had happened, but upon running a second 27/3 on the sample in question, it clearly wasn't a crisp pass after all.
While it's possible that you are getting perfectly crips passes that still fail ASTM for total glycerin, I would suggest using a bigger vessel for the test, and multiplying the ingredients to magnify the fallout. Also, a graduated, tapered vessel can help. Obviously, temperature and time are very important.
We have a Gas Chromatograph ("G.C."), but have been relying more on our SafTest equipment, which in my opinion gives more repeatable (if not as precise) results, and is easier to train people on and use on a daily basis.
Current dogma tells us that 68deg is the Important temperature. What is the important time and how was this determined?
There are various resources around the web, including in the original infopop posts about Jan Warqvist's method, and others by Andrew Morris I think, that go into detail about optimum temp and time.
For my part, I've found that analyzing results less than 10 minutes after performing the test may give you the very dangerous "false pass". Sometimes, oil droplets simply take longer to fall out of solution. On the other hand, if you wait longer than 30 minutes, you can have a "false fail". Because, in the past, I wasn't able to hold temperature steady as well as I can now, this may have been more due to temperature drop of the ingredients. At any rate, my advice, based on my own experience and what I've read, is no shorter than 10 minutes, no longer than 30.
Try searching for posts from Andrew M
Andrew did extensive testing of the 3/27 test and verified the 30 minutes.
I agree with you about 10 minutes being the least time to wait and for the reason you state. However, if the only reason you say to not go past 30 minutes is because you could not hold the temperature steady then the false fail would be because of a temperature problem not a time consideration.
I can not find anywhere where Andrew M verified that after 30 minutes the test becomes unreliable. My own experience has been that if you hold the temperature steady and keep the container airtight there should never be any drop out.
If you can not hold the temperature steady that is a temperature problem not a time problem.
Southside, you're probably right. I don't worry about it too much, because the 10 minute minimum is working so well with us, and we don't retain 27/3 samples. If we need to retest fuel, we take it from the sample that we did the SafTest on, and we retain those for a long time.
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