Ive been using the 3/27 test for over a year now and I think most homebrewers would agree that it is the most useful test we have available to us.
However it has its limitations, it requires a bit of experience to judge the results and it gives a only a pass or fail result.
I decided to have a go at making the test a bit more useful with an accurate measurable result. as always Ive tried to avoid expensive lab equipment, using stuff we all have lying around.
As you can see from the picture the test vessel is a 2 litre milk container, Im sure you have something similar in US. I made 6 or 7 mm hole in the cap and using a hot glue gun I stuck a short length of 8mm internal diameter transparent tube to it. I sealed the other end of the tube with a small plug and some hot glue. Voila! my test apparatus was finished.
To calibrate the tube I filled a syringe with water and squirted in 1ml, I marked the level with a pen. I repeated this for 2ml and 3 ml. Since I was going to use 30ml of biodiesel for the test the 3 ml mark would represent 10 percent of the test sample or 90% conversion.
Now to use the tester I poured in exactly 270ml of methanol and 30 ml of biodiesel. I fitted the cap and shook the container up and down 5 times. I then hung the container upside down for 15 minutes.
This biodiesel was from a batch which had already failed the 3/27 test but I was curious to know exactly how bad it was. As you can see the undissolved oil filled the tube to the second mark giving a result of 93% conversion, not good but not hopeless either.
I did a second test on a sample that had passed the 3/27 test and it gave me a result of 98%, much better.
All the tests were carried out at 17 degrees C
These results are encouraging and I feel will help me to make better biodiesel. I was particularly pleased to find out that a sample that passed the basic 2/27 test actually contained 2 percent unconverted oil.
I don't claim to be a 3/27 expert, but I am pretty sure there is no direct correlation between fall out volume and conversion percentage. There might be a rough correlation, but the fact that the conversion reaction produces intermediates (triglyceride to diglyceride to monoglyceride to methyl esters) that have differing solubility in methanol, the fallout volume can be a mix of these.
Example: 0.1ml of pure trigyceride fallout, had it been pure diglyceride, would have been about 0.2ml, or 0.3ml had it been pure monoglyceride. Now imagine a mix of these. Now factor in that, say, the monoglycerides are 66% (totally made that up) soluble. 0.3ml of mono- would only show as .1ml of fallout.
Plus there are certain oils for which the resulting methyl esters are not methanol soluble (fish oils, if I remember right). If your oil sources are relatively constant, and you verify your percentage calibration through trial and error of reprocessing, you can make a one-off test rig calibrated to your own system, but I fear it would have to be re-calibrated for every different person's system. At least as far as 2 people not being able to accurate compare fallout volumes and have it mean anything.
I appreciate that the test is not universal and can only be applied comparatively to consistent oil supplies processed by the same method. But a home brewer should be able to use this method to get a clearer idea of how well his process is performing and what difference in terms of conversion any improvements might make.
Your point about the different volumes of tri,di and mono glycerides is a valid one but the increasing solubility of these compounds offsets this problem, at least partially. In your own example the mono glycerides would have read exactly the same as the triglycerides although I appreciate you made up the figure of 66%.
Perhaps someone on this forum could tell us the comparative solubility of di and monoglycerides.
But essentially you are right, this is not an absolute measurement and it makes no sense to compare readings from different oils and different processes.
It could still be a powerful tool to help fine tune the process and achieve the best possible biodiesel.
Dont forget to give it a name,but something more glamorous than 'the milk jug test'
-how much time are you leaving the test sample to settle before reading results? I have read in a recent post by Kumar that less than 10 minutes or more than 30 minutes can result in erronious readings. 17C is a bit cool for 3/27 that can give false fail? Tom
" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
On the JtF site where the original test was posted by Jan Warnqvest using the quantities of 25 ml of biodiesel dissolve into 225ml methanol to perform the test Jan says, "The biodiesel should be fully soluble in the methanol, forming a clear bright phase. If not, there is pollution in the biodiesel. Each ml of undissolved material corresponds to 4% by volume."
Huh...I wonder what that is based on.
1 part in 25 = 4%
To keep thing totally consistent I have used the same technique I always use for the basic 3/27 test. I shake the sample up and down 5 times and then take my reading after 15 minutes. I always use 17 degrees C which is 63 degrees F. This means chilling the samples,the methanol and the test jar during the summer months in a small cool box before testing.
The 3/27 test is very temperature sensitive and sticking to a consistent temp is important if you want meaningful results.
As you said in the last post 1 part in 25 is 4%. Because I use 30ml of biodiesel 1 ml of fallout will equal 1 part in 30 or 3.3%.
I only calibrate to 3ml or 10% because I reckon that if you have less than 90% comversion you need to reprocess.
A few points about making the test bottle, when glueing the tube to the cap make sure that the tube does not protrude through the cap. This would create a hollow where fallout will collect in the cap instead of flowing down into the tube.
Use a plastic bottle not a glass one as you may have to squeeze the bottle gently to expel the air out of the tube. This will not work with a glass bottle.
Ive been away on holidays for a few weeks, drove my old Skoda to Italy and back, got there on biodiesel but had to buy dinodiesel to get home. Uggh! I had forgotten how smelly and horrible that stuff is, and the price, ouch!
When I got home four test samples had arrived in the post. ( I offer a free water content testing service to home brewers in Ireland and UK.) I decided to test them for conversion as well and got the following results...94%, 91%, 89% and 83%.
I contacted the owners of the samples and found that the 94% sample had been made using the 2 stage process, the other 3 had used single stage processing.
The 83% sample had been processed for only 30 minutes after adding the catalyst. The owner uses it in an old model Mercedes and found it worked fine but occasionally had problems with emulsions during washing.
The best 3 samples had passed the basic 3/27 test
I understood the 3/27 test was to be done at 68 deg F. If much less, it would give a false reading.
The other question I have, I thought if there was ANY fallout, it was considered a fail. So if you have a 2% fallout, isn't that a fail? I can understand the quantitive aspect of this test to compare failed samples but just wanted to clarrify these two points. Thanks.
"This biodiesel tis a cruel and heartless mistress we home brewers have chosen"
You are right about 68 degrees being the correct temperature for the 3/27 test. I began doing the test during winter and found 63 was easier to achieve in my workshop. I stuck with it because it made it harder to get a pass and encouraged me to work harder to get very high conversion.
When I developed this test I stuck with it because I wanted my results to relate to my earlier results.
So when I do the test and get a result it is probably a bit low, I suspect by about 2%. What I would like to do is have a sample analysed for exact conversion and then adjust my temperature until it matches the correct conversion result.
I find that samples that pass 3/27 can contain as much as 8% unconverted oil ( by my admittedly low scale).
I got a sample in the post this morning and I tested it with both the standard 3/27 test and my own larger scale test. This sample had been made using the 2 stage process by some one I know who is careful and methodical so I expected it to be top quality.
Sure enough the 3/27 test showed a clear pass almost immediately with no visible fallout.
When I tested the sample with my test outfit it registered 98% conversion, the best Ive measured so far.
This test was carried out at 20 degrees C or 68 degrees F and from now on all my tests will be done at this temperature.
Last week I made a botched batch. I inadvertently left my pump on the lowest setting instead of the highest while processing. I didnt notice anything was wrong until about halfway through washing I had a serious emulsion, the first Ive had for over a year. I broke the emulsion using glycerol and continued to wash . Even after the soap was gone the bio was still a dirty orange juice colour. something was really wrong. I tested it using my larger scale 3/27 test ( I must give it a name) and sure enough I had only 80% conversion.
Reprocessing was the only option. Normally when reprocessing the amounts of catalyst is guesswork but I decided to base my amounts on the results of the test, It was a 150 litre batch so it must contain 30 litres of unconverted oil. That would require 7 litres of methanol and since my original titration number was 9 I would need 270gms of KOH. I upped these quantities by 10% to be safe and went ahead and reprocessed.
The reprocess yielded more glycerol and the bio washed easily. The test at the end read 98%, one of the best batches Ive ever done.
The test proved very useful when reprocessing.
Posted October 11, 2010 04:06 AM
As many of you know I have been offering a free testing service for the last year or so, testing for both conversion ratio and water content. Many of you have availed of the tests, so many, in fact that it has begun to interfere with my day job.
So Im going to have to make a small charge for tests in future, the good new is that I have added a third test to the set.
Conversion Test, measured in percentage points, accurate to 1%.
Soap titration, measured in parts per million, accurate to 5%.
Water content, measured in parts per million, accurate to 5%.
Just post me a 300ml sample in a well wrapped plastic soft drinks bottle and enclose a cheque or postal order for 20 euro ( or 17 GBP) and your email address. I will send you the results within 24 hours of receipt.
I think this price is fair as it takes me half an hour to carry out the three tests, and to have fuel tested for astm standards by a lab costs at least 750 euro. The service remains free to all my customers who have bought processors from me.
The Railway Station
I have been able to check the accuracy of my test. A friend works in a lab and he made a batch of biodiesel. For several reasons he got very poor conversion so he took it into the lab and had it analysed. The result was tryglycerides 15%, diglycerides 1.9% and monoglycerides 0.06%.
He gave me a sample and I tested it by my method and it read 83%, almost exactly the same. So I think I can safely claim that my test is accurate to 1%.
Since I developed the IMB 30/270 test a few months ago I have been testing the conversion of every batch I make. At the beginning my average conversion was 96% using single stage processing. By fine tuning the system and processing in 2 stages I pushed that up to 98-99% . This week, for the first time, I managed 100% conversion.
The secret was a process heater. Once the oil was heated to 65 degrees I switched off the immersion heater and switched on a 200w silicone rubber mat type process heater which I had stuck to the outside of the processor drum. This remained on for the full 5 hours of 2 stage processing and at the end the temperature had only fallen to 56 degrees instead of the usual 48.
These heaters are really good because they heat gently and there is no danger of boiling or flashing the methanol as there is with an immersion heater. They are expensive, about 70 euros from Radionics
.ie but if you want to make the best possible bio they are worth it.
I just referred someone to this post but realized that he may not find it because it was on page 3 so here it is Frankle. i hope it is of use to you.
Excellent, IMB, I had read it some months ago, but am suffering a little from information overload!
2001 Citroen Xsara
2002 VW T4 Transporter
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