I was reading how the 3/27 may be "too good a test" and people were using their fuel as is before the test was readily used. So I decided to take a sample from a washed and dried batch that show a bit of fallout on the 3/27 test. After reprocessing and letting sit overnight I had about 3ml glycerine from a 1L test.

How much is too much? Is any fallout bad? I figure from this test its about 0.3%

Artesp

-Tests for biodiesel quality are just that. If your not concerned about meeting astm standards, then you could use that bio
-there and lots of people that burn straight wvo. And I’m sure they wouldn’t bat an eye at using under reacted oil.
-under reacted oil presents other problems, like it’s harder to wash, it becomes cloudy at higher temps and so on
-each person has to make a decision as to what the minimum standard will be for them. for example I process until I get a clear 4/27
-I'm assuming here that you had 3ml of unreacted oil drop out, not glycerine Tom

A lot of it depends on what motor you intend to run the under reacted fuel in. The older MBZ's run fine on it, the TDI's might not.

Before 3/27 I could count on a fuel filter clog and lift pump failure with the first cold snap in the fall. Has not happened since I learned to run a better fuel. Before 3/27 I had no way to judge the quality of my fuel. Now with 3/27 and the Imanometer I have a pretty good picture of my fuel quality.

Tom,

I guess my previous posting wasn't clear. I took 1L of finished biodiesel and re-processed it just for kicks. Out of 1L of the bio, about 3ml of glycerine dropped out. Somewhere I read, I think it was Tilly that posted, that one of the tests (not sure if its the ATSM test) only required 96% conversion.

Is my math correct in stating that in the above example, it produced 0.3% glycerine? I don't know if this can further be stated as a 99.7% conversion?

artesp

-then this batch pass 3/27, then further reaction created some by-product. The reaction is not complete at 3/27 pass, but sufficient to pass astm. Is the reaction ever really complete? I don't think so, and your test shows this Tom

quote:

Originally posted by artesp:
Is my math correct in stating that in the above example, it produced 0.3% glycerine? I don't know if this can further be stated as a 99.7% conversion?

You will find that the large majority of the drop out will probably be methanol as well as some soap. If you can safely evaporate away all of the methanol you will get a better idea of how much glycerin dropped out.
I do not know if there is a correlation to the conversion rate of the biodiesel.

For the sake of simplifying the calculations, there are a number of assumptions involved. These are not based on data, just done for sake of simplification. Feel free to adjust the model as is suitable.

Assume 2ml of glycerol in the 3ml of dropout (remainder being methanol). In that 2ml of glycerol, there are ~0.0274mol of glycerol molecules.

2ml(1.26 g/ml)(mol/92.1 g) = 0.0274mol

Lets assume that these molecules were all bound in monoglycerides with linoleic acid. The molecular ratio is 1:1. The total mass of these monoglycerides is ~10.21g.

0.0274mol(372.6g/mol)=10.21g

The total mass of the test reprocessed sample is ~0.86kg=860g.
The unconverted percentage is approximately 1.19%, so conversion is 98.81% (mass/mass ratio). Note that this percentage is a ratio of glycerides to esters, not glycerol to esters.

10.21g/860g =~1.19%

If we assume that all 3ml of fallout are glycerin, then conversion is ~98.22%.

I am not sure how the quantity of drop-out in a reprocess test can tell you the conversion of the reprocessed biodiesel.
Several of my friends have had to reprocessed a batch of biodiesel 2 or even 3 times before it passed the 3/27 test.

quote:

Originally posted by Biotom:
Artesp

... -there and lots of people that burn straight wvo. And I’m sure they wouldn’t bat an eye at using under reacted oil... Tom

I've always wondered that. Isn't what drops out in a 3/27 test unreacted oil? If so, it would be the same thing that people use straight? I know in those systems they heat up the WVO to reduce the viscosity. But why would it not be okay to have a tiny fraction of it left in the bio?

It has been common knowledge for years that if you use low conversion biodiesel your engine will self destruct. Fortunately none of my engine have ever heard about this and continue run just fine on low conversion biodiesel over the years.
So have my friends who use biodiesel.

None of us have common rail or DPF

Ha, I wonder if I ever mentioned it to my vehicle?

Now that I think of it, I can recall some time ago someone explained to me that the drop out in the 3/27 test is not the same as straight WVO. It is left over mono..something or another. That is what is bad to the engines over some time.

The drop out is probably triglycerides. However there will probably be more mono and di glycerides in partially reacted biodiesel than un-reacted Veggie oil. The mono and di glycerides are more likely to hold moisture than triglycerides.
If your biodiesel is dry then this is not a problem

artesp

-I always concidered the drop out to be unreacted wvo. place 3ml of unreacted wvo in 27mls of methanol, see what you get 3ml of dropout. Tom

your right Tom..

I dont think its common knowledge that unreacted oil self destructs engines.. although mine would tell me it doesnt like it like when it made me replace an injector... but of course mine is a fussy model..

But for the most part I personally think a large portion of the homebrewers actually run unreated BD without ever knowing it..

quote:

Originally posted by biogirlz:
your right Tom..
I dont think its common knowledge that unreacted oil self destructs engines.. although mine would tell me it doesnt like it like when it made me replace an injector... but of course mine is a fussy model..
But for the most part I personally think a large portion of the homebrewers actually run unreated BD without ever knowing it..

Good to hear you are another person who realizes that many diesel engines do not require high conversion biodiesel.
I was reading about your problems just the other day. I thought the problem was incomplete washing or plugged filter, not low conversion biodiesel. Or was that a different problem you had
I think most people are using biodiesel that does not pass ASTM

Unreacted oil= triglycerides

"I think most people are using biodiesel that does not pass ASTM"

Like I said at the begining of this thread, it all depends on what motor you run it in. I don't know if my bd passes or not but I make it and test it to the best quality I can.

quote:

I was reading about your problems just the other day. I thought the problem was incomplete washing or plugged filter, not low conversion biodiesel. Or was that a different problem you had

yes you are right. When I started dry washing I had to demeth first. I didnt realize that with KOH if you demeth then you have a slower drop out... the soap plugged my system