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ASTM D6751-08 Tests explained w/ Home Brew Equivalent Tests

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September 21, 2014, 04:57 PM
ASTM D6751-08 Tests explained w/ Home Brew Equivalent Tests
Hi Tom,
Yes,you are correct,absolutley loaded with soap.
When the glycerol is "cracked" with conc sulphuric,the middle layer (glycerol) contains no soap (it's wet and very acidic,but no soap)
I re-neutralise this with KOH in water and bring it back to pH 7.0

I then mix this with my bio(when dropout test passed)
Three washes with this brings the soap level down from @ 3000ppm to <200ppm.
The good thing is that it can be used several times before being less effective.

My friend from the commercial factory told me about this years ago. First time I was in 2 minds to add it-scary!

Makes the lovely clear bio go all murky, but boy does it work well.

No need to de-meth or bubble wash,just go ahead and pump wash.

When I put up the post re shake-up test I had been experimenting using virgin Glycerine as the last wash and obviously not got rid of it all,
September 21, 2014, 07:00 PM
Thanks Dave, that clears things up for me. I didn't realize that you where splitting the glycerin out. If I remember correctly the methanol remains in the glycerin layer.

" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
September 22, 2014, 04:56 AM
Hi Tom,
Yes I think your correct,and also If the methanol is left in the glycerol it seems to give a "cleaner"split.

It will be interesting to see how long the pure glycerine lasts before it doesn't absorb the soap as well.

At the moment I just use it for the last glyc wash,I only use @ 10-15 litres of glyc for each wash for 300 litres of bio.

The disadvantage of the pure glycerine is the cost.It has reduced in price recently but is still £40/20 litres.