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This system was invented by Sean Parks of Davis Ca and improved on by El Jefe de Biosmell.
Originally posted at equipment forum by Girl Mark

article copyright 2003, 2005 by Maria ‘Mark’ Alovert / Biodiesel Homebrew Guide

This design allows you to build tanks out of old 55-gallon drums very cheaply without needing to find a conical-bottom or dome-bottom tank. It has two valves- one valve drains water, and the other drains from a higher level- draining only biodiesel when you’re finished washing. I prefer this tank design over a conical bottomdraining tank- with this one I can save my last wash’ water for reuse and to just drain the clean biodiesel from above it.


The tank is a closed-head drum, turned upside down so the bungs face downwards, with the former bottom (no-bung) end cut open. A sawzall or a jigsaw works perfectly for this. You really need a metal drum for this, but people have figured out a few ways to do the same thing with plastic drums also.


To the left is the tank, with a plywood cover on it, so as to contain any methanol fumes that are present in the beginning of washing.





Clear plastic tubes on the two drain valves are very important to allow you to see what you’re draining- clear PVC eventually becomes milky and you should replace the tubes with new ones at that point.




Parts needed:

* 55-gallon or 30-gallon closed head drum (the type without a removable lid)
* drum deheader tool, or sawazall, or jigsaw, or cold chisel, used for cutting off one end of the drum
* Plumbing: All parts 3/4” unless otherwise noted. All parts black iron or galvanised (except ball valves which are brass) Yes, black pipe will rust, no, it doesn’t matter very much in this application. PVC ball valves tend to break off their non-PVC plastic handles when exposed to biodiesel…
o A. one Bushing: 2” to 3/4”
o B two 2” pipe nipples
o C. two 90 degree elbows
o D. Two 3” pipe nipples
o E. Two Ball Valves
o F Two hose barbs. I use grey plastic ones, not available at every hardware store, but cheap. In san francisco area they’re at OSH or Yardbirds’ not at Home Depot. Home Depot has white nylon ones.
o G. Two pieces of 3/4” clear vinyl tubing long enough to reach to a bucket or a floor drain.
o H standpipe: a piece of pipe about 8” long
o I one coupling

[Total length of H and I should be 1/4 the length of your wash tank- if you use 1/4 water to 3/4 biodiesel when you wash]

* Teflon pipe thread tape or teflon paste. Tools needed: one Pipe wrench, one pair of large channelock pliers or crescent wrench, and a flathead screwdriver for hose clamps.

Assembly details

* Water drain: The 2” bung gets a bushing threaded into it, and this receives a valve assembly for draining wash water. When you need to change your wash water you drain it using this valve. You stop draining when either emulsion or intermixed biodiesel/water starts coming out of the clear tube. You probably won’t be able to drain every last bit of water out of the flat-bottom tank..
* Biodiesel (standpipe) drain: This is used when your biodiesel is washed and you are ready to move it into storage or to a filter or to your vehicle. It is assembled this way:

Thread pipe nipple “B” into the 3/4” bung as far as it will go. Threads should protrude inside the tank about 1/4 inch. Assemble coupling “I” and standpipe “H” together, then climb inside the tank with it and screw the assembly onto the short protruding threads. The rest of the plumbing looks just like the lower drain. You may want to label which drain is the standpipe to avoid confusion. I use fullsize two milk crates stacked together as the stand, and strap the tank to the wall using heavyduty webbing or water heater strapping.

The Stand Pipe wash tank also has a few variants Utahbiodiesel has one that works for poly tanks. And an article from WVOfuels on making a better wash tank.