Dewatering WVO

Most filtration systems only take out the food particles and water that is in droplet form.  Waste oil also contains water that is suspended in the oil, which as I stated earlier, carries acid and will corrode parts of your fuel system causing expensive long term damage.  There are processes and methods to remove this.

If you pour your clean filtered oil into settling tanks and leave it for a few weeks, it will separate into a lovely tan looking fluid at the top which you put in your fuel tank, and a sludgy grey brown gunk at the bottom.  The sludge is a blend of animal fats, fine food particles and water.  It can be taken back to the fish and chip shop and placed in their waste oil bin out the back as they’ll get paid for it, or you can heat it up to condense the water and then run it through a settling process again.

To test if there is any water in your oil or your sludge, you can do a hot pan test.  This test is not necessary if you can see water in the sample.  Keep the sample to be tested handy, enough for 6mm to 8mm thickness covering the bottom of the pan is best.  

Heat a  pan on high and smear a little of the sample across the pan until the smear begins to produce smoke, then pour in the sample.

Look closely at the bottom of the pan where the oil meets it. If there are very small bubbles forming, it indicates some suspended water. The number of bubbles indicates how much water is present in suspended form.  Lots of small bubbles is unacceptable and will do damage to your injection system. If the oil is crackling or popping, then there is way too much water is present, and the fuel will have to be treated or settled.

There are filter powders available on the market that can be used during the filtration process as it will attract water and other free fatty acids and is relatively inexpensive. 

It is sprinkled over the surface of warm oil and will attract water as it falls through.  It should then be agitated for a while so that it makes maximum contact with the oil.  The powder is rated at about 60 micron and must be filtered out before you put the oil into your fuel tank. 

Some takeaways are now using this product to clarify their oil as it is safe to use with food grade oils.  You could perhaps talk your  take away shop into using it.  It can be purchased from their filter supplier, and will increase the quality and life of their oil.  The downside is that you’ll only get half as much fuel but it is better quality.

There is a well recognised brand of this product called Magnasol which is available from Vegiecars.com.  I have used the Magnasol product on filtered oil that I pick up from my chip shop.  After filtering it with Magnasol, there was half as much sediment after settling, and no water in the hot pan test.

I use a fuel processor in my vehicle that collects the molecules of water on the filter and coalesces them into droplets that fall to a bowl at the base.  There are several companies that make units that will perform this task as explained later (see Fuel Processors).  This allows me to pick up filtered oil anywhere and use it immediately, without having to stand it for several weeks to settle out.