Freeze Dried Friday

Filtering Oil

This was a slow week for the freeze driers again. We just fired one of them up on Wednesday to run a batch of basil. Today we are finishing up a batch of tomato sauce. However, I’d like to ask SurvivalBlog readers a question.

We currently filter our oil after every run through a simple oil filtering setup made out of plastic jars and an automotive oil filter. The issue with the current design is water in the oil. If you allow water to enter the oil filter, it will not exit until the filter is full of water. At that point, you have to either change the filter or tear the setup apart and drain the water out of the filter. I’ve seen two ways to get the water out.

  1. Use a capture jar with a shoulder on it when you drain the oil from the pump. Then let it sit for about an hour and the water will settle to the bottom. You can then carefully pour the oil into the filter, leaving the water in the shoulder of the jar as you pour. Because of the design of Mason jars, you can’t get a perfect pour and avoiding all water means you will lose about 1/4″ of oil. We currently get around that by not dumping that water/oil until the jar has been used for many oil changes and the water accumulates to a larger amount.
  2. Freeze the jar of captured oil. The water will solidify and the oil will get slugish. You can then up-end the jar when you pour into the filter without having to worry about the water. This method certainly avoids all water, but the sluggish oil doesn’t pour very well from the jar and you end up wasting about the same amount of oil in the long run. It also takes much longer as you have to add in the freezing step.

So, how do you avoid water in your filtered oil?


  1. This works on planes so I would assume you could downscale it. Oil floats on water and the water gathers on the bottom so make a container with a funnel like bottom, attach a short length of thin clear tubing with a valve on the bottom. The water will go to the tubing, you open the valve drain it out and you will be able to see the line between water and oil. Stop right after the oil line passes the valve. Then in theory you should have pure oil left in the container with only a small lose of oil. I bet after a couple times you would be able to time the valve just right as to only lose a couple drops of oil per cycle.

  2. Use a diesel fuel/water separator assembly.
    You can buy a “filter head” at NAPA with pipe thread holes on each end so you can connect into your system, then ask them to recommend a common diesel fuel water separator filter. They have a bowl at the bottom sometimes but almost all have a small petcock valve at the bottom that you can open up and drain the water out with.
    The diesel fuel filter should be plenty good enough to keep your oil clean and then you can buy several and put away.

    1. This is the best solution. Frank Lindhardt has designed a flush kit but uses a oil filter. I think a diesel fuel filter with a drain would work best in his design. He runs the oil through this flush kit with out the mess of removing the oil.

  3. I use a ‘diesel’ fuel cartridge filter (designed to install between a pump and nozzle), with a 2 qt funnel on filter housing inlet. This I located just below pump for ease of draining vacuum pump. This filter unit has a water drain valve on bottom. Cold oil takes a couple hours to pass filter. Also I use $10 gallons of dairy-vacuum pump oil from the farm store.

  4. I have a question.. I have tried to package freeze dried squash (yellow crookneck, spaghetti, acorn) using QT mylar bags and 300cc O2 absorbers, and they remain inflated and do not compress like everything else I package this way. More air volume ratio in squash?

  5. I purchased four gallons of oil with my FD. This gives me enough to have backup and perform this:
    Upon shutting off the pump, I drain the entire pump oil into a clear, 2 liter soda bottle while it is still hot. After about 4 or 5 oil drains, the bottle is full. Let it sit a couple weeks. The oil on top of the water and residue will be much cleaner than the oil passed through the filter. The oil will be very clear. You will then be able to slowly pour most of the oil off and leave the residue in the bottom, since it is a tall, narrow, bottle with a good shoulder.

  6. Freeze the jar of captured oil to remove the water, and then filter through a roll of Scott 1000 toilet paper for a clear oil. That’s much cheaper and does a better job than an oil filter.

    1. This is what I do too, and it works great. I drain the oil from the pump while the pump is still hot and then let the oil sit on the counter for 12 or more hours for the oil and water to separate and to let the sediment settle (I don’t know that this is necessary). Then I freeze the oil for a day and then pour it through a toilet paper filter in a Brita water filter jug. You can use a spatula to help scrape out the thick oil from the container that you froze it in. I don’t often rinse the oil collection container because having a nice layer of water in it when you freeze it helps to make a thick slab of ice in the bottom. If there is only a little water at the bottom (not enough to cover the bottom of your container), then you end up with some free pieces of ice that dump out with your oil which defeats the purpose of freezing to separate the water and oil in the first place.

      1. It’s not necessary to let the oil sit to allow the water to separate. If you place the jar in the freezer at about a 20 degree angle you’ll see the water collecting immediately in the bottom.

  7. Leave your oil in the freezer over night to solidify the water and then pour the oil out leaving the frozen water in the bottom of the jar to be dumped out.

  8. We do everything you have mentioned above. I don’t think there is any way to completely remove the water other than the freezer method. Yes, it adds a step but it doesn’t slow us down because we have 5 gallons of the oil and several containers in the filtering process. Here is what we do:

    1. We have 2 filters set up as we filter the oil twice before putting it back in the vacuum pump. Our filters are not car or engine filters. We purchased 2 from and took them apart to see how they were made. Inside the filter chambers were coffee filter paper, a PVC pipe to distribute the oil evenly, and what appeared to be classic low loft batting.

    2. Let twice filtered oil sit until water is settled on bottom. Put in freezer. When the water content is frozen we pour out thick oil.

    3. Store filtered oil in container to be reused.

    4. Don’t wait for the filtered oil because we have the other gallons of oil so we just add new oil to the pump while we are waiting for the oil/water to freeze.

    5. Once we have enough of the filtered oil accumulated we recycle instead of adding new oil.

    I find that there is less oil wasted with the freezer method than pouring non-frozen oil and hoping to stop the water before it pours out.

    Also, making the homemade filters saves money instead of buying engine filters.

  9. Instead of an automotive oil filter check out Semi-tractor diesel fuel filters. Some have a water separator spigot on the bottom. Fuel (oil) floats on top in the filter, water can then be drained out the bottom.

  10. I do not have a freeze dryer (yet), but my Grandmother would put broth with grease in the fridge over night. The grease would sorta solidify and then she would get it out that way. Would the oil do something like that?

  11. Heat and hold the oil temperature over boiling point of water for your given altitude. Water will off gas from the oil, but does take time. You will want to keep the temperature below the point where your oil will start to degrade and coke up. Putting it in a flat pan (to increase surface area) in the oven at 225F to 250F for several hours might work.

    Let the oil cool before using.

  12. Thanks for the ideas about the water in the filtered oil. While I change the oil every time I use the FD, I have not yet reused the filtered oil so this will give me ways to remove the water.

    I am still FDing chicken breasts; it takes about 32-34 hours to FD 10 pds so at this rate I have another week of chicken to do. I use a meat slicer to get the chicken down to between 1/2 to 5/8 inch thickness, then I spice and brown the chicken in the skillet. I let it cool before putting in the FDer. When it comes out of the FDer it goes into mylar bags with O2 absorbers and a bay leaf, and then into a latch-lock storage container.

    Have a great week; prayers for those in IRMAs path.

  13. I got tired of draining, pouring, filtering and refilling. I always had an oily mess on the table. I had originally purchased a power flush kit but it caused too many pump problems. I had broken valves and leaky shaft seals. I came up with a system that works for me. I use two buckets and a 10 micron hydraulic filter. I use the pump to push the dirty oil into the top bucket. The oil flows through the filter into the bottom bucket, trapping the debris and water in the filter. The clean oil can be returned to the pump by a hose and ball valve.
    The filters last about three months and just spin off. They are mostly full of water and debris at this time. I tear the pumps apart and clean only when the shaft seals start to leak which is maybe three times a year. We run two standard sized units.

  14. In the lab, in order to remove water from an organic layer (the oil), we do a two set process. First, as others have mentioned physically separate the oil from the water that is at the bottom. Next place a few ounces of anhydrous calcium chloride in with the oil and allow it to sit for an hour or so. The oil you pour off will be dry and you’ve accomplished it without energy expenditure. The Anhydrous Calcium Chloride can be reused until it forms a sludge at the bottom of the container. Save the sludge and use it in the winter time to de-ice driveways, etc.

  15. Use the same method that is used in racking wine or mead. If you already have clear jars just get a 3 ft. piece of clear plastic food grade tubing and use the same method to pull off the oil.

  16. I forget what is called but they make a fryer filter powder makes a solid out of water so it can be filtered out of the oil. Check with a local restaurant supply company.

  17. Use a gravy separator. The tea pot design allows you to pour off the water first and then filter the oil.Just look on Amazon or do an online search. For those of you who don’t know it’s a kitchen gadget.

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