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BioDiesel Class 101

Class # 7 - Drying BioDiesel

    Drying BioDiesel can be done in various ways. A lot depends on your local humidity & temperature. Drying BioDiesel can be as simple as placing a cheese cloth over the top of an open drum & letting it sit around for a month or two & if you live in a very hot dry climate a few weeks may dry it. Most methods of drying will only remove dissolved water & will not dry up pooled, or high amounts of suspended water which will eventually drop to the bottom where it will pool over time.

    If your like most people, you don't have the room or inclination to wait weeks or months for your BioDiesel to dry so we have a couple of other ways to dry BioDiesel. If you have nice hot dry weather with low humidity (below 50%) you can get away with simply pumping your BioDiesel through a shower head exposing a large surface area to the air & allow natural evaporation to take place. If on the other hand your weather is cool or you have elevated humidity or you expect the temperature to plummet soon, you will need to heat the BioDiesel and pump it through a shower head to expose a large surface area to the air allowing evaporation to take place. Both methods work rather quickly in an hour or two your BioDiesel should be bone dry.

The Drying Method

  1. First, let the BioDiesel sit a few hours or overnight after doing your last Bubble Wash so any relatively large droplets can fall out of suspension. Drying works wonders but it can't work miracles, nothing will remove pooled water except for pumping or siphoning it out.

  2. Using the measurement (BioDiesel to tank lip) that you took at the beginning of washing, use that measurement as a guide to insure the wash water level is at least 1" below the fuel stand pipe drain before starting to drain out your BioDiesel. Using the Stand Pipe Washers (stand pipe) Fuel drain fitting, Pump the washed BioDiesel into your Drying tank. For further information on Stand Pipe tanks buy our PGB book.

  3. You can use our "All in One" low fume Processor for Drying or a stand alone Drying tank both of these design plans are in our PGB book which we highly recommend you get. Either of these Drying tanks work well for drying your BioDiesel although a stand alone dedicated Drying tank will speed up production because you can be processing a batch of BioDiesel while your drying another batch.

  4. Using a Pump you will pull washed BioDiesel from the stand pipe fuel drain fitting in the washer & pump it into your Dryer until you have emptied out the clean BioDiesel in the wash tank. Some BioDiesel should remain below the stand pipe in the washer. Follow up by draining out the wash water & then catch the last inch or two of wash Water & BioDiesel in a clean container. Oil cubes from a restaurant work well for this. Let the cube sit around until the wash water & BioDiesel separate then siphon out the wash water & any emulsion into another oil cube. Next take your salvaged BioDiesel & put it into your Drying tank as well. Save the emulsion & wait for it to break apart in a few days, you can add this BioDiesel to your next wash.

  5. Depending on the local temperature & humidity levels you can choose one of two ways to rapidly dry your BioDiesel. Air Dry it with heat or just Air Dry it. Both methods circulate the BioDiesel up through a shower head (as detailed in our PGB book) to expose broken up droplets of BioDiesel to the air. Normally drying with heat takes about an hour in 70% or less humidity, drying without heat in less than 50% humidity can take a similar amount of time. However drying without heat does have it's risks, see our book for details.

  6. You will notice the BioDiesel change it's appearance from a tad cloudy to a bit more transparent. This usually indicates it is dry. We suggest testing the moisture content before placing it into your vehicle! Testing is simple & takes only a half an hour or so. Failure to get dry BioDiesel can damage your fuel injection system & as they say an ounce of prevention is worth a pound of cure. Besides if BioDiesel contains enough moisture from insufficient drying it can cause water to precipitate or rain inside your fuel tank if the fuel temperature  drops sufficiently. Water will damage your injection pump & injectors in short order.

  7. Always test for moisture content 2 ways!  Refrigerate a sample at the coldest temperature you expect for the duration of time that you will be burning that batch of BioDiesel & look for condensation. Weigh, Heat & dry a sample to verify moisture content.

And you thought we forgot.....

  1. How long does it take to dry BioDiesel that is left in a drum & covered with cheese cloth?

  2. Can you dry the water left pooled in the bottom of the BioDiesel drum?

  3. What is the quickest way to dry your BioDiesel if the temperature was 45F & the humidity was 80% ?

  4. What will happen to the moisture content of your BioDiesel if you simply circulate it through a shower head without heating it & the relative humidity is 95% ? Hint: Get our book to find out.

  5. How can you tell at what temperature the moisture (if any) in your BioDiesel will condense out at?

  6. At what temperature do we heat BioDiesel for drying when using a shower head?

  7. What can occur inside your vehicles fuel tank if not quite dry BioDiesel is pumped in during the day & the temperature plummets that night?

  8. What happens if moist BioDiesel in your vehicle fuel tank condenses out into precipitation and water & is burned along with the BioDiesel in your vehicle?


The next class Moisture Testing


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Last modified: 11/26/16