Oil Collection Tank Using Vacuum - Collaborative Biodiesel Tutorial

In a previous post that I cannot seem to find now girl mark said something to the effect of "collecting wvo is a time consuming and expensive part of making biodiesel" for her group.

It does not have to be.

I use a simple and cheap "oil sucker" which uses a salvaged (free) refrigerator compressor to create a vacuum (25") in a salvaged (free) water pressure tank. These tanks are commonly available in sizes from 5 to 120 gallons and are easily capable of safely withstanding the pressures involved.

In the top of the tank I have a needle valve ($3) screwed into the port provided for a schreader valve. I use 20' of 1/8" poly line ($1.20) to connect the compressor to the tank. which I load into my pickup bed or small trailer on collection days. and store in the corner of my garage the rest of the time.

In the bottom of the tank I connect a 20' section of cheap flexible hose ($10) to a brass ball valve ($4) via a few nylon barbed fittings ($4). On the other side of the ball valve I have 6' of clear flexible poly hose ($2) so I can see if I am drawing crud or clear wvo from the dumpster. This allows me to skim the best wvo off the top of the wvo in the collection container...and leave the rest to settle more. Eventually I have to suck the accumulated crud out of these tanks using the same unit and dispose of it...but those making biodiesel may find it ok to simply use even this dirty bottom crud.

When I arrive at my wvo source I slip the cheap clear pipe into the wvo and barely open the ball valve allowing me to determine if the end of the "suck" tube is sitting above the layer of crud. Then I secure it with a simple clamp and open the valve all the way. At a rate of about 4 gal per minute the wvo is sucked into the evacuated tank and quickly fills it to within a few inches of the top before the rate of flow decreases noticeably. I have a cup of coffee, talk to the owner/manager/cooks, or read a book while the tank is filling since there is no pump to damage when/if the pipe sucks air. When I was collecting for a co-op I had several units in the truck so I
could pull from several collections tanks at once and speed my day along.

Usually these wvo collection tanks are 55 gallon drums I provide...since most restaurants with grease hauling service have "exclusivity" agreements with the haulers. Once the wvo is in a grease haulers dumpster it is often their property and even the restaurant owner cannot "give permission" to take it. Once the tank is full I simply drive home and connect the compressors "pressure" side to the tank, slip the "suck" hose into my holding tank, and open the ball valve. Soon the tank pressurizes and the wvo flows out of it even faster than it was sucked in.

This is a simple and cheap manner to collect wvo without pumps or lifting. Since I have a "corporate" policy of sharing much of the fruit of my R&D for free I would be happy to elaborate more on the "system" or even provide pics and diagrams if there is interest. Let me know if you want more info.

For a downloadable pdf version go to http://vegoilconversions.netfirms.com/newpage1.htm and select "Wvo sucker collection unit schematic"