I have a few questions regarding conversion. Most times i do the original Jan Warnqvist test (25/225), as opposed to the 3/27 test. my results vary somewhat in that I either get NO fallout, or sometimes I get a 1ml fallout, which, as I've read, equates to about 4% fallout, or a 96% conversion. My question: what would be considered the "De Facto" homebrew standard? I have a 1996 E300 Diesel Mercedes(normaly aspired) and a 2007 2.5 Ford Ranger (pre-DPF). Would these 2 vehicles be OK running 96% converted fuel? My next question is, IF these cars are NOT OK with running 96% converted fuel, what quantities should I use if I re-proccess? I know the "rule of thumb" is 30% of the original titrating figures (ie: if your original titration was 1, making your NaOH 6grms, youd use about 2grams), but from what i understant, this is for VERY POORLY converted fuel. Should I stick to the 30% when re-proccessing, or should I use less, and do I ALSO use 30% of the original methanol (ie: 60ml of meth per liter of oil, instead of 200ml)?
My oil titrates rather high at 2.5-3, if that helps
i wouldn't worry about it. tri's are good fuel, and mono's are great lubricant. soap, free glycerin, and water concern me more. i don't think it's worth the effort to repro.
you might consider tweaking your process to improve conversion slightly. higher titrating oil usually requires a bit more caustic. a bit more heat or a bit more reaction time might also help. if you are concerned about conversion, then a two stage process is definitely the way to go.
thanx for the reply.
I usually use the 2-stage process, with better results- but this particular time i had an out of town friend who was staying with me for a few days, and he wanted to see how I make my diesel. i opted for the single stage process to simplify my demonstration for him. He is very interested to also "get into the game", and i thought that if i keep it simple, he might be more inclined to start making his own.
I do think my "problem" is with my reaction time. I mightve "rushed" the mixing time a bit for the benifit of my friend. And something else, durig this last batch, the glycerine fallout was very high. usually my settling yelds about 15 to 20% glycerine, but on this last batch it was very close to 30%... could it be too much caustic?
poor yield can be caused by high soap production. the soaps pull biodiesel down into the glycerin layer. high soaps are a function of too much caustic, or too much water, or too much mixing time/heat. i think water is usually the culprit, followed by improper titration (titrating fluid or phenol).
i find there is a tradeoff between yield and conversion. higher conversion = higher soaps = lower yield. it's tough to find the sweet spot, especially when your oil isn't always the same.
You and I must have very different ideas of what "conversion" means. To me, conversion means oil turned into biodiesel (and not glycerin or undesirable byproducts like soap). For me, high conversion = low soap = high yield. I don't think I have misunderstood this for all these years that I've tinkered around with WVO and biodiesel.
I suppose if you count "conversion to soap," then what you said makes sense. As you said, soap is minimized by a proper titration followed by reaction in the absence of undesirables like water.
Just an update on my poor yeild of the previous batch.. What i havent mentioned is that ive moved recently, from a farm to town, which ment that allot of my stuff went into storage. during all this i mustve missplaced one box which had odds and ends in it - amongst others my new bottle of Phenol Red. When i made this batch (my first at my new home), i couldnt find my newer Phenol Red, and used and older bottle i had. I strongly suspected this bottle is the culprit. The reason a bought a new bottle is because i suspected that this one might be past its "Best Before" Date. I have a sneaky feeling my titration figures was wrong, due to the expired Phenol Red, and that lead to more caustic, which lead to poor yeild... Time to visit the swimming pool shop again... :-)
At the risk of being patronising which i dont want to do at all, you do know of using turmeric for titration, yes?
If i am stating the obvious tell me to shut up.
"In times of universal deceit, telling the truth will become a revolutionary act" - George Orwell
Yes, i know of turmeric for titration, but for whatever reason, i like phenol red (I dont know why, i have no reason other than personal preference), and no, I didnt take your post as being patronising. We all are here to learn, and had I not known about turmeric, that wouldve been valuable information.
conversion = biodiesel (kg) / (biodiesel + tri + di + mono) (kg)
"yield" = biodiesel (kg) / original oil (kg)
"yield" can be over 100%, so it's kinda not a true yield but its a convenient measurement. i believe 109% is theoretical max yield.
you can certainly have high conversion and high soap. i've astm tested my fuel and it was very high conversion, but my soaps were near 3000 ppm, which i would say is high soap. it's all in how much caustic is used. more caustic pushed the conversion higher, but also makes more soap.
be careful with the phenol red. the pH range is a bit lower than phenol, so i suspect you could be underdosing a bit. i perfer a slight overdose on cuastic than an underdose.
I aggree andyman. In the past I have managed 105% yeild, with zero fallout during the 3/27 test. The above is usually what I aim for in my batches. About your Phenol vs Phenol Red comment, I didn't know that you get both. I always though Phenol and Phenol Red is the same thing. English is not my first language, so I assumed some people "abreviate" Phenol Red by calling it just Phenol. I'll look into that. Possibly my bottle that got lost in the move was indeed Phenol, and not Phenol Red, and that the bottle I'm using now is Phenol (or vica versa), which would explain the different results...
I use phenolphthalein indicator solution to test vegetable oil. Its a carcinogen, maybe, but I don't drink it. I have considered yield by volume not mass. So 1 litre of corn oil might produce 1045 millilitres of biodiesel, theoretically. Except Soap making reduces the yield because the fatty acids that make the soap don't make biodiesel. The product biodiesel has unreacted methanol in it so that increases the volume. I consider that after purifying the biodiesel that I can calculate the yield (by volume). Thanks
Ronny, I understand that yeild has nothing to do with convertion. I don't know if your post was directed at my previous post, but if it was, I didn't mean to make it sound like the 2 are related. I mearly meant that those 2 things (yield and convertion) are 2 early indicators just after ons has processed, to determine whether one is still "on the right track"... Obviously there are other things to test for aswell (soap, water, glycerine etc), but when I said that my "aim" is 105% yield and zero fallout during the 3/27 test, didn't mean for it to sound that the 2 might influince each other. I understand that the 2 are mutually exclusive, I mearly wanted to state "my version" of good quality diesel. Usually I would process (2 stage), and right after processing I would look at % yield and 3/27 fallout. If these 2 (seperate) indicators show around 105% yield, and zero fallout, I am confident enough to proceed with washing. Now, I realise that after washing the yield may drop further, as one keeps taking more contaminents out of the diesel, thereby reducing the volume. But the 105% is (for me) an early indicator that I got my calculations right as far as my titration was concerned. I also need to mention that I usually do 2 3/27 tests, one where I draw diesel from the top after I let it settle for a short time (to give any contaminents a "chance" to settle to the bottom-i do this because I haven't washed the diesel yet, and I figure that drawing from the top, would "simulate" washed diesel. I also do a second 3/27 test after "mixing things up a bit", to be able to compare the results). I know this is not scientific, but also remember that I said these are "early, preliminary" tests to indicate whether I can proceed, or whether I'm wasting my time with a bad batch, that could (maybe) benifit from a reprocess.
Sorry for the long winded posts, but as mentioned earlier, english is not my first language, and I tend to "over explain" as I'm not always sure I'm making myself clear.
yes sorry, phenolphthalein is the indicator commonly used in titrating oil. i'm sure phenol red would work fine as well, but you may need to adjust to compensate for the slightly lower endpoint.
quick question. If i use Phenol Red instead of Phenol, do i need to add more caustic, or less?
Just use turmeric and be done with it, its accurate, cheap and non hazardous...
Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
quick answer: read my posts above.
Phenolphthalein and phenol red are not the same thing, but they both change colour at about pH 8.2. So do you add more or less caustic? Well, it should be the same amount, neither more nor less. The pH of free fatty acids is acidic, so I think the phenol red ought to work to determine how much free fatty acids are present.
According to Wikipedia phenol red pH indicator is yellow at pH 6.8 and pink at pH 8.2 and above.
This is the most important point in the discussion, because soap, free glycerin, and water cause more problems in the fuel system than a few percent of clean VO in an under-converted batch of BD.
To minimize soaps, would under-reacting for a conversion of 90-95% of the VO to BD, thus create less soap and free glycerin dissolved in the residual methanol?
I prefer BD with the least amount of soap, free glycerin, and water dissolved in the residual methanol; yield and conversion rate are less important. These dissolved contaminants can pass trough filters then fall out of solution when the methanol evaporates. When this happens inside the fuel system it can cause significant problems.
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