Hi,

I would like to know if anyone of you have had problems with the 3/27 test.
It happen that after waiting 1 hour of letting the biodiesel separate from glycerin (at that time glycerin separates completly) I performed a 3/27 Test, and it passed, 100% conversion.
Then after one day of settling, I just wanted to proof the 3/27 test an it happen that it failed!!(conversion around 95%), then after 2 days the results were still dropping (about 80% conversion), after 3 days reached 75% convenrsion and so on...... Today conversion was about (60%)
Could anyone explain me what is happening? (Im testing it in unwashed biodiesel).

I'm using Waste vegetable oil (titrates at 3.5 gr NaOH), I'm using a base of 5gr/NaOH.
Is the excess of NaOH still reacting on the Biodiesel?, and makes the reaction to go in the opposite direction converting it again in triglycerids?
Well, hope anyone could help me explaining what is actually happening.

p.d. I also made a test batch with virgin oil, (5 gr/L of NaOH and 20% MeOH) and the results where the same: the 3/27 test drops everyday...
Thanks

Temperature is the same everyday

furzuga
-are you doing new 3/27 each day or just observing the original one, if the methanol is allowed to evaporate, then the bio will settle out more and more . There is NO revese reaction. so I'm not sure what you are seeing.

Hi Biotom,
Yes, I'm doing everyday a new 3/27 Test.
I'm wondering what is actually happening?

I was thinking to to the 3/27 test with washed biodiesel, just to check if changes...

While I test unwashed bd the test during processing, you should depend on should be done on fully washed and dried bd.

quote:

I would like to know if anyone of you have had problems with the 3/27 test.
It happen that after waiting 1 hour of letting the biodiesel separate from glycerin (at that time glycerin separates completly) I performed a 3/27 Test, and it passed, 100% conversion.
Then after one day of settling, I just wanted to proof the 3/27 test an it happen that it failed!!(conversion around 95%), then after 2 days the results were still dropping (about 80% conversion), after 3 days reached 75% convenrsion and so on...... Today conversion was about (60%)
Could anyone explain me what is happening? (Im testing it in unwashed biodiesel).

How are you determining the percent conversion from 3/27?

At what temp was each test done?

Have you washed and dried a sample and done the test on it?

Are you taking each sample from the same layer of fuel, or are you taking from lower layers later?

Hi Andrew, regarding your questions:

_ 1. I'm determining it by multiplying by 4 the mL of oil that didn't dissolve in methanol, then I substract that % to 100%

- 2. Well,I think temperature is my problem. I'm doing it at ambient temperature (perhaps 24 C more or less)...

3. I'm washing now the biodiesel just to compare with the unwashed one. I let you know what my results are.

4. And for the last question, no, actually I'm taking each time from different layers....


If the temperature of biodiesel is hotter then it would dissolve more in methanol??

The test has to be done at what temperature? The biodiesel should be also at the same temperature? What about the methanol?
I think my problem is with temperature.... Today was hotter, and I got better results....
How do you manage to have everything at a same temperature?

quote:

Today was hotter, and I got better results....

Yes - temp change will change the results. That is why I asked about it.

I suggest doing the test at 68f for 30 min. Assuming your goal in doing the test is to know if your fuel is likely to be at or near ASTM levels of bound glyceride. (This is no absolute.)

Put the jar with the methanol in a water bath at 68f until the temp is stable. Then add the BD. Best if it is near 68f too. Once the the BD and ME are mixed, observe it every few minutes over a 30 min. period. Any fallout, however small, indicates a fail. The size of the fallout is related to the degree of under-conversion, but no quantitative relationship has been established, AFAIK.

HTH.