Vegetable Oil Filtration

So…veggie oil filtration…I’m almost afraid to write this as there are as many different filtering setups as there are people running on veg. I should preface the rest of this by saying that this is how I do it; I’ve read a lot and seen different setups, and this is what I’ve been using and it’s what I’m comfortable with. Some people put together filtering rigs that cost many hundreds or more and might insist that I’m not doing enough. Much of the information out there is second-hand or anecdotal, so I suggest reading up on all you can and go with a filtering setup that you feel most comfortable with.

I started out very low-tech and low-cost, just to get started. I bought a big 20-quart lobster pot and poured in a 5-gallon container of used oil, then put it on the stove. Heating the oil makes it go through the filter much faster, and supposedly removes free water in the oil. I cooked it on ‘hi’ for about 20 minutes until it was nice and hot, then poured it through a sock filter suspended over a 5-gallon bucket. I use the double filter that Greasecar sells, which is 5-micron on the inside and 1-micron on the outside. Recommendations vary about what micron size to filter to, but I’m more comfortable with 1 micron instead of 5 or 10; what the heck, it doesn’t cost much more so why not? The 5-gallon buckets I keep the filtered veg oil in have pour spouts in the lid, and handles so it’s easy to carry and pour into the veggie tank in the trunk. I generally fill the buckets and let them sit for 2-3 weeks before using. Even after the filtering I notice small particles that settle at the bottom of the bucket after a few weeks. Gravity and time are your friends.

The lobster pot worked well but I use about 10 gallons per week, and cooking on the stove took some time. That setup was also messy. God forbid you accidentally spill a little oil on the outside of the cooking pot, so that it gets onto an electric stovetop burner. I did that once, and caught shit for weeks. Between the smoke and the smell, it’s best to be avoided. Also, pouring the heated oil into the filter was often messy, despite my best caution and protection for the floor. From there I worked on a more involved filtering setup that was faster, cleaner, and more efficient overall.

Here is the setup that I currently use: I bought two 55-gallon metal drums from a local barrel-reconditioning place for around $12 each, with quick-lock removable lids. The first barrel is my settling drum. I bought a 100-micron barrel filter off Ebay that fits over the top of the drum, and the nylon mesh filter catches much of the larger particles. It’s easy to take off the barrel filter and shake it out to clean it. I bought a utility transfer pump from Home Depot for $75, and I pump the oil from the settling drum to the other drum, which is ready to filter, then I pour more oil into the first barrel through the barrel filter. To heat the oil in the barrel before filtering, I use a 1,500-watt water heater element wired to an extension cord. I picket this up from Home Depot for about $15. I drop the heater to the bottom of the drum, pull it up about a foot, and plug it in. It heats the oil FAST, so I do that first thing, then get all my buckets and sock filters in place. In about 20 minutes that oil is hot. I then pump the oil out of the second barrel and into the suspended 5-1 micron filter and into the 5-gallon bucket. To make things go faster, I usually suspend 4 sock filters over 4 buckets simultaneously and keep filling up the filters with the pump. I always take oil from the top, since the particles tend to settle at the bottom. Vegetable oil is not a conductor of electricity, so I don’t worry about dropping the wired heater element into the drum. For my liability sake, I’m not saying YOU should do this. I always make sure I’m closeby when the heater is plugged in, and the barrel lid is on in case there is a problem.

I should stop and address some issues that some others may raise, to save them from emailing me.

First, de-watering. People seem to agree that water in the fuel is very bad. Many people go far beyond what I do in attempting to remove any water from their veg oil. Again, it’s largely second-hand and anecdotal information out there, so do your homework and do what you feel comfortable with. My first defense against water is to only take used oil from fryers that is poured directly into the 5-gallon cube containers, not into outside grease bins that could get water in them.

I’m just guessing here, but I doubt that the heating I do makes much difference with de-watering. Fryers heat the oil VERY hot, much hotter than what I do, so I’d argue that if heating evaporates any water from food cooked in the oil, water is a lot more likely to dissolve in the hot fryer oil than in my drum, no matter how long I heat it up, but that’s just my guess.

People use different methods to heat in a metal drum. Some people use drum heaters that wrap around the outside of the barrel. In my opinion, these do a great job of heating the air outside the barrel, and also the steel of the drum itself. Oh, and eventually the oil gets hot. Oh, they also cost an arm and a leg. Some people also use heating units that sit at the bottom of the barrel, surrounded by a cage. These also can cost a lot of money. Look into them all, but for me, I’ll stick with the water heater element. I’ve seen or heard of people using residential water heaters or solar hot water panels. Too complex for me. I keep in mind that my free time is scarce and I don’t want to spend hours a week making fuel for my car. When I could spend those hours making money or doing more enjoyable things, I could save the hassle and just buy new oil from the store – it’s often cheaper in bulk than diesel fuel.

Another issue I might get cranked at over is heating near the bottom of the barrel, which can cause the settled particles to rise with the heated oil (cavitation). I don’t know how you beat physics on this one. If you put the heater near the top of the oil, the lower stuff won’t heat up for a looooooong time.

Some people use enclosed filters attached to filter heads, attached to a transfer pump. The filter heads and housings can be pretty expensive, especially if you have several in series using different micron filters. I’m also concerned that the pressure from the transfer pump would push through small particles that would otherwise be caught in a sock filter, which filters by gravity. I have no evidence that one method is any more effective than the other, I’m just more comfortable with the sock filters.

So that’s how I filter my veg oil. The Greasecar forum has many ideas that people have tried, so I’d suggest starting there and see what others do.