"If oil is first filtered to 10-30 microns then heated to about 80-90F and held there in an insulated drum for 8 hours, the top 2/3 will be water free."

What if the variables are different?
What if the oil is strained to 100 micron and heated to 180? How long will it take for any water to settle? Is there a citable reference for this information?

I have 50 gallons of strained oil, which I have heated today in three batches to 180 F. Now it is all in a stand pipe wash tank and I intend to let it settle for a day or three. Then take off the upper oil through the stand pipe. I believe this should yield 30+ gallons of clear oil to process.

I am starting with my reliable supply of restaurant oil which has more non-oil solids/sludge than I like, but it titrates as good oil. The collection barrel behind the rest. has a semi-solid 10" layer of batter sludge in the bottom. I know because I pumped out all that was liquid above it and that is what was left. What I am trying to do now is mimic the settling that occurs in the restaurant barrel and only take off the best oil to process. This crud is not straining out easily through my 400 (doesn't catch much) 200 (collects a layer I can scrape off the mesh), and 100, which oddly, was not catching scrapable crud, nor stopping much of it that did filter through.

This actually worked very well. I drained off the upper oil and got my best separation ever, in one processing pass. I can run the pump to circulate it to a brown. Turn it off and watch the clear layer over dark glycerine separate in about three minutes. So I figure the steel wash-tank is my "oil-in" dryer/settler. Now, I need to make another steel dryer tank for output.

Have a look at this for some ideas
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/15960555...611079412#7611079412

That is an interesting no heat, passive pass through design.

The reason I heated it to 180 f. is because the batter sludge holds water, and getting the water out was actually my first priority. After straining I ran the hot oil through a brass lawn sprinkler head for a spray pattern, and air exposure. I blew some compressed air through the spray, until I realized I was creating a WVO mist in my garage. The fact that the solids settled out was a related bonus.

Speaking of compressed air, I was also using an air gun to blow sediment off the filter bag and back into the solution in the bag increasing flow dramatically for a few seconds. Too much labor. I will settle and dump the sludge every third or 4th time.