Hello all
Over the past several years I've successfully made many dozens of batches of BD. For about the past 25 batches I have begun performing the 3/27 test and typically gotten a variety of results ranging from very little to no fall out, to an accumulation of several match head sized droplets. I think I'm always very careful about how I produce the BD and perform the 3/27 tests, conscientious of consistency in my process etc. Can anyone here explain what variables exist that perhaps I may not be controlling properly or is the amount of variation in my 3/27 tests par for the course?
Thanks. P

Proper ratios and temperature I would say are the most important. Temperature being the hardest one to control. Peerhaps that's where your variables are coming from. Are you letting the bio settle before exracting your sample?

PD
-not warmer than 68F, or the test could indicate a false pass, I keep the temp of my 3/27 at 64-65f, in hot ambiant temps this is not easy, so soak the sample container in cold water, or start with ice cold methanol (I keep a jar of methanol for 3/27 in the freezer) Tom

Letting settle, yes. With the 3/27, I agree temperature is difficult to control. I wonder how much a variation of say 5 deg. F has on the amount of fall out?

PD
-if your conversion is just on the edge of pass/pail, 5F will have a large effect of pass/fail result, if the process is pushed further to the right, the temp change has little effect Tom

quote:

if the process is pushed further to the right, the temp change has little effect

Please explain further?

PD
-when I complete the single base stage, conversion is at a point that 3ml of bio will desolve in the methanol, but not 4, or 3 ml will desolve but some flakes of amber or white stuff will settle out. So I always push the reaction further with a repo using 10ml methanol and 1grkoh/ltr of oil. after this, 5/27 will be achived, no problem, and the methanol/ bio mix will be perfectly clear Tom

Agree with tom, if you have very high conversion (using the suggested formula makes fantastic fuel) then there really is almost nothing to fall out at any temperature

quote:

Originally posted by Biotom:
PD
-when I complete the single base stage, conversion is at a point that 3ml of bio will desolve in the methanol, but not 4, or 3 ml will desolve but some flakes of amber or white stuff will settle out. So I always push the reaction further with a repo using 10ml methanol and 1grkoh/ltr of oil. after this, 5/27 will be achived, no problem, and the methanol/ bio mix will be perfectly clear Tom

Thats very interesting! Do you do that on every batch?
Have you tried this with Naoh? I ask this because I have had issues on a reprocess with my entire batch turning to gel using Naoh... Not fun!
Jon

quote:

then there really is almost nothing to fall out at any temperature

I disagree.

Some fuel I had that tested .09% for FTG would fail around 50f, if I recall. I can look at my notes if anyone wants more details.

I don't think maintaining 68 should be difficult for anyone,you just have to get the
methanol ready ahead of time in a water bath.

Jon
-I switched to KOH 5 years ago for that reason, and have never looked back. Koh biodiesel requires one extra wash, but glop is not an issue. Tom

AT 50F , some high melt temp esters will fall out! Tom

Andrew,
Im just speaking from my own experience. If I put my 3/27 in the fridge and its good fuel, it will stay very clear. Pop it in the freezer, and yes then I get chunkies starting to fall out. As tom said, higher melting point esters (saturated, longer chains, etc).

Ive said this before, but I think the 3/27 is also a cold weather operability performance indicator as well as a conversion test. Once you reduce the temperature you can start to see what is falling out

quote:

AT 50F , some high melt temp esters will fall out! Tom

Tom - firstly, it seems that there are not much high temp ester in my samples, since they remain clear down to 30f or so.

Secondly, have you seen well converted high melting point fuel have fallout on 3/27 at a given temp when the same level of conversion fuel from other feedstock does not? I have not seen this.

quote:

Im just speaking from my own experience. If I put my 3/27 in the fridge and its good fuel, it will stay very clear.

If you are passing 3/27 at fridge temp, doing the whole test at that temp (45f), I'd suspect that you are at least 2x under ASTM for glycerides, assuming you wash well. Perhaps you have a need for VERY converted fuel, or you like the comfort of a wide margin for error.

Andrew
-this past summer I seen biodiesel made from bacon fat. at amient temp, that day, was 28C there was a white solid layer on the bottom of the sample about 3/16 of an inch thick (high melt temp esters). this biodiesel passed the GC tests. I can just imagine what 3/27 would looked like on that stuff even at 68f.

quote:

this biodiesel passed the GC tests.

What were the #'s for mg, dg, tg, total g and free g?

Andrew
-I don't know, but they have their own GC machine this was one of many samples on display by the Canaidian International Grains Institute. Tom

Tom,

Passing GC with no numbers doesn't really tell us much about how converted the fuel is.