... as described at:
http://www.biodieselcommunity.org/testingforsoap/

I am confused as image six in the procedure states:
" Starting with this color Titrate using .01N HCL solution"

but then next image (7) states:
"Neutralize this by titration to yellow using your lye/water solution that you have in your acid value (i.e. free fatty acid) titration equipment"

then the remaining images seem to suggest adding from you HCL until color change end point.

Can someone clarify step 7 in this procedure for me?
thx

I use a streamlined version of that soap test. It is on my webpage where I sell kits. You don't need my kit, I just put the procedure there to help people out. It may be a little clearer once you read mine.
http://www.fryerpower.com/store/page2.html

-Jim

Thanks Jim, yes your instructions are very helpful.

I just thought I would post about the tutorial, so that any confusion may be cleared up (unless I am the only confused!).
thx,
rob

I think the pictures are out of order. I remember having a LOT of trouble getting it figured out last year. You are not the only one...

-Jim

The soap test you are following is not completely correct. This is the method I usesoap test. It was written by Dr. Gerpen. There are a couple of issues with Girl Mark's procedure. One of the issues is that she doesn't address someone using KOH instead of NaOH as a catalyst. Another issue is that in order to get ppm, you would need to multiply by 3044, not 30.44, if you used NaOH as a catalyst.

Another possible confusion is that it states to neutralize to yellow using lye/water solution...shouldn't this be your HCL solution?

No, it is right in that part. Alcohol goes acidic if it is stored too long. Adding lye/water blanks the titration so that you are starting from the right point every time.

-Jim

I understand the need to blank acidic alcohol..but that would before doing the HCL titration..but the way it reads on the site looks to me like:

Picture 1 : just a picture of ingredients
Picture 2 : another pic of needed stuff
Picture 3 : STEP 1 - start with 100ml of solvent
Picture 4 : STEP 2 - add .5ml of bromoblue
Picture 5 : STEP 3 - add sample to be tested
Picture 6 : STEP 4 - This one is a little confusing..it states "Starting with this color Titrate using .01N HCL solution". To me this sounds like you are to start with the blue liquid (sample in solvent with bromoblue)..and start adding your HCL.
Picture 7 : STEP 5 -?? Now it states to neutralize this titration to yellow using lye/water.

Isn't this out of order/incorrect?

Should you not blank the titration with lye/water PRIOR to titrating with HCL?
In fact..should it not be prior to even adding the sample?

1. start with 100 ml solvent
2. add bromoblue indicator
3. neutralize solvent - with base and appropriate indicator if suspected to be acidic.
I would think this would be lye/water until indicator is BLUE.
4. add sample to be tested
5. add .01N HCL as needed to go from blue to yellow
6. Calculate

Yep, there are more steps than photos and I made a massive mistake in the captioning for the photos. I think I wrote this in the middle of the night one year, and I NEVER do it this way myself (*I always do a volume-based titration so as to determine how much acid to use for some kind of neutralization procedure, rather than determining PPM soap)- so I haven't really followed the problems and no one else in the biodieselcommunity.org team has either for lack of time.


Please submit corrections to the article's writing forum at www.localb100.com/forum and they'll actually get fixed- I havne't checked in here to the soap article section in a while.

The exact place to submit changes is here:
http://localb100.com/forum/viewtopic.php?t=20

In general, even though we have an INfopop forum for asking questions about the processes discussed in the biodieselcommunity.org article, the writing forum is over at www.localb100.com/forum- which is confusing, but keeps the writing forumn from dealing with newbie questions and keeps the 'submissions' and 'suggestions' and 'corrections' all in one place that's separate from a discussion forum.

It certainly leads to additional problems and confusion when corrections happen here and don't get transferred over there, and I apologise about that!

Will do.
Thanks!
-Rob