Hi all, Here is a shortened rant on making bio-diesel. I collect old cooking oil from some food outlets in 20 litre snap-top drums. My refinery is an enlarged 210 drum to 250 litre on a stand with an element from an old hot water unit and a stirrer driven with a washing machine motor ( about 450 rpm). It has outlets bottom and side. Another smaller drum about 45 litre to mix caustic and menthol together. Heat 200 litres of old oil strained through fly wire to about 55c. Fill second drum with 36 litres of menthol - (18% of oil content ) and carefully add and stir measured amount of caustic*, mixing with paint stirrer for 5 min., tip into hot oil and then mix for one hour. Shut down and wait 2 to 3 hours, then drain off soap through bottom tap. Crude soap will set as cools, it is potassium salt, glycerin, soap and some cooking waste, flour etc.traces of menthol can be heated out for health reasons later. The rest is first class diesel to be filtered and stored. It is best left a week or so. * caustic amount is worked out by Taking one gram of caustic (15.43grains) and add to 1 litre of water. (lye water = lye) Now take 10 ml. rubbing alcohol in small jar and add 1 ml. of hot oil then add a ml. at a time of lye till ph. paper turns heavy green. New veg. oil has a value of 3.5 grams of caustic per litre, old oil varies. Most of my brews take about 5 ml. of lye to turn green e.g. 5 plus 3.5 = 8.5 equates out to 8.5 by 200 = 1.7 kg of caustic to work. Be carefull of fumes and caustic, cover up and protect motor as fumes will shorten electric motor's life..... and yours. I fit a lid on refinery. Have now travelled about 30,000 klms. trouble free in my old Cruiser on the clean fuel. If any of the list need detail of this, E-mail me at Cheers old Bob.

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