How to Get Water Separated From Oil in an Oil Drum
Separating water from oil is necessary if you're making biodiesel or running your car on waste vegetable oil. The techniques in this article will work for fuel oil or automotive oil as well, although heating these oils is not recommended.
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Things You'll Need
- Siphon hose or pump (hand or electric)
- Five-gallon bucket
- Immersion heater (optional)
Instructions
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For the best results the drum with the oil and water should be undisturbed, and kept at above 60° F. The natural behavior of oil and water is to separate, with the oil rising to the top and the water sinking to the bottom. However, vegetable oil thickens at lower temperatures and the natural separation is inhibited as a result. At 80° complete water and oil separation may occur within a few hours, while at 40° it may take several weeks. If the drum is at the right temperature the oil may already be separated and you can skip to Step 3. Fuel oil and motor oil do not thicken the way vegetable oil does and should separate from water even at lower temperatures.
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If the temperature is too low for adequate separation (or you don't have the luxury of waiting), and moving the barrel is not an option, you will need to either transfer the mixture a bucketful at a time to a container in a warm location, or heat the barrel and/or its contents. Commercial immersion heaters can heat the mixture in the drum to allow for proper separation. Do not attempt to heat fuel oil or motor oil, as this can be dangerous.
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To remove the separated oil you will need to suction it from the top into a bucket at ground level. Many hardware stores sell a small pump that attaches to an electric drill and transfers liquids through two hoses. Just be sure you stop pumping before you get to the water level under the oil.
If you wish to remove the water from the drum, leaving the oil behind, you will have to use a pump and a hose that will reach to the bottom of the drum. A siphon will work only when moving liquid from a higher level to a lower level. Watch carefully for the point at which the water is gone and the pump begins drawing oil.
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Tips & Warnings
If using a siphon to transfer the oil, be careful not to ingest or inhale any when using your mouth to start the suction. Better still, you can purchase a siphon with a compression bulb at most auto-parts stores, so you don't have to use your mouth at all.
If the oil is to be used for making biodiesel or as a fuel, you will need to filter it carefully to remove particulate matter.
While vegetable oil is not very combustible, care must be taken in heating it. If you are using an immersion heater, follow the directions and any warnings carefully, and never leave the mixture unattended. If there is any way to move the mixture to a warmer location for separating, that is preferable to using a heater.
