Beta Testing a Mixing Eductor

By Rick Da Tech


Plastic Tank Mixing EductorWe used this mixing eductor in a test with 12 people to see how well it would work in an Appleseed Processor. I put together a little kit to install it in a standard appleseed. There were a couple of testers that used an upside down water heater or AppleTurnover. These testers had to fabricate their own install kit since they were not using the same ports we used on the standard Appleseed.

The kit consisted of the eductor in the picture above along with a length of 1/2" black pipe and an adapter nipple. The adapter nipple was a 3/4" x 4" black pipe nipple with 1/2" threads cut on the inside on one end. Also since the eductor was going to have to be inserted through the upper element hole, we added some twine to fish the eductor through to upper element hole and out through the anode rod hole.

Biodiesel Mixing Eductor Kit

Before going too far with this, I tried it out on a drum of oil. The video is using the largest nozzle from the eductor above. I also tested a nozzle made from pipe. As you can see in the video the eductor really gets the oil moving around in the drum. The pipe fitting version was less effective, but even it offered a major improvement over no nozzle at all.

Using the plastic eductor:

  • 0.125" dia = 48 psi
  • 0.156" dia = 40 psi
  • 0.188" dia = 30 psi
The 1/8" x 2" pipe nipple
  • 0.269" dia = 30 psi

The pump used for testing had a maximum pressure of about 50 psi.

Mocking up the Biodiesel Mixing Eductor

Here you can see how deep into the Appleseed we wil be installing the eductor. The hot and cold water ports on the water heater are fitted with ledges to hold a dip tube in place, so we had to use the anode rod hole for our return line.

We dropped a string in through the anode rod hole and fished it out through the upper element port with a wire coat hanger. Then fed the string through the inside of the 1/2" pipe and eductor and tied a washer to the end. Then fed the eductor in the element port then pull the string coming out of the anode rod port until the 1/2" pipe was sticking through. Then we screwed the 1/2" pipe into the adapter pipe and screwed the assembly into the water heater.

Once it was installed we replumbed our return line and put the spare element back in the upper element port to plug it up. Then it's time to run a test batch.

installing the eductor

On my first batch I wanted to test out the appleseed for both reducing the methanol and fast loading of the methoxide. Normally I use 22% methanol add the methoxide over a 20 minute period and mix for two hours before passing the 3/27 test. On this test I was able to urn 18% methanol, add the methoxide as fast at the pump would pump it in (under 2 minutes), and still pass the 3/27 test with 1.5 hours of mixing. I was sold.

The beta testers had similar experiences. One tester said that before, he had to use the base/base process to pass the 3/27 test, and after he was able to use the single stage base method. Another tester reported passing the 3/27 test in under 30 minutes using his old recipes. Before it was taking him several hours to pass.

top view of eductor installation

The beta test showed unquestionably that using an eductor with our little blue pumps make huge improvements. Some of the testers were worried about the pressure building up on the pump and drilled out the nozzle to 1/4" and still saw the major improvements.

Finished with eductor install

Now for the down side. This little plastic eductor did not instill confidence in the beta testers for it's ability to survive long term inside a processor. The general consensus was a desire for a metal eductor. There was also a bit of concern over pressures involved. The plastic tubing many of us are using on the return line is normally not heavily pressurized. With an eductor it becomes pressurized and is more likely to fail sooner. The solution is to go with an all steel return line.

One additional issue I noticed after the beta test was that the amperage on the pump rises from about three amps up to about six amps when using an eductor. The higher the pressure the more amperage it will draw. At max pressure it will draw about 8 amps. This can be an issue if you are heating and running the pump at the same time on the same breaker.

Related Links

Beta Test Discussion Thread on Infopop


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