Thoughts on the 3/27 test.

[Julian]

I was doing 10/90 tests today instead of my usual 3/27s as I wanted to try and achieve a more accurate/obvious result.

Musing on what I was doing, my train of thought went thus ... if I get a "perfect" pass, what would happen if I added more methanol to the test.  The only answer I could come up with was nothing.

If that's the case, is the maximum amount of methanol critical?  I can see that the minimum is critical because I assume 27ml of methanol will be saturated by 3ml of biodiesel.  So assuming incomplete conversion a 3/30 or 3/40 should show the same drop out as a 3/27.

Sits back and awaits incoming!

[julianf]

Are triglyerides insoluble in meth, or do they just have a low solubility?

[Tony]

Amount of methanol is unimportant so long as fatty acid methyl esters can dissolve in it.

Solubility and temperature are also related, which is how we ended up with the Fahrenheit scale (rather foolishly scaled against water with salt impurity -but that's a whole other story).

The 3/27 is an excellent way of measuring FAME conversion, because there is a huge excess of methanol, which counters the problems of solubility vs temperature, because there is a LOT of solvent.

Consider say 3/277, 5/455 testing.  I would be surprised if they showed any different to 3/27 or 5/45

So I would say a clear 3/27 pass indicates 100% conversion at room temp.

The same might not be true if there was a lot less meth at lower temperatures - but we're so far off that, that it's pretty irrelevant.