Plantoil/diesel conversion basics
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Carimbo

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Hi,

Using a standard Dana simple prefilter unit, has been serving me well for almost a year and a half. Last few times I run it, the result fails the hot pan test miserably. Even tried letting the heater (1200W 220V element wired to 110V) run 5 days, even after 5 days I was still hearing popping from the droplets hitting the element. Frustrating.

What are the probable causes? Like I say, it has been working well up until recently.
danalinscott

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Reply with quote  #2 
Have you drained the emulsion from the bottom of the unit occasionally? Eventually enough will accumulate to reach the level of the heating element and then it tends to remix constantly rather than settling out.



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Carimbo

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This is the second consecutive batch with this problem. During the first time (2 weeks ago) I drained 2-3 gallons out of the bottom-mounted valve but it did not appear to be an emulsion. Looked pretty clear, but with numerous small black flakes which I'm guessing were shed from the heater element surface? Had that painty odor but otherwise seemed normal-looking. Source is non-hydrogenated soy from a Japanese teriyaki lunch restaurant, possibly a bit overused because it's oftentimes quite dark in color. Think rootbeer vs. honey.
danalinscott

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It is possible that your wvo is contaminated with a solvent. That painty smell is often an indication of this.
WVO contaminated with solvents will cause the Hot Pan Test to give false positives for water in the form of small bubbles. This is solvent rather than water turning to vapor bubbles in the pan.

Is there a painty smell during the HPT?
Try bubbling air through a sample for 10-20 hours and retesting. This should drive off most solvents from the sample and show significantly fewer bubbles in the HPT.

Solvents mixed in VO will not settle out as water does.

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Carimbo

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HPT quickly creates lots of medium size bubbles, which stick together in clumps as they ride along the pan surface before rising to top. Soon after creates somewhat fewer more dispersed smaller bubbles.

Not quite painty odor thrown off HPT but not quite "foody"-smelling either. Hard to identify, but maybe a burnt odor?

Wish I had a way of pumping air bubbles through a sample to test for solvents.

What solvents would be in the WVO?
danalinscott

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Reply with quote  #6 

Quote:
Originally Posted by Carimbo
What solvents would be in the WVO?

I have seen all sorts of contamination in WVO...from used engine oil to vinegar.

From your description of the HPT results it is possible that you are heating your pan too hot before pouring in the wvo sample. This is the latest version of the HPT:
Quote:

The hot pan test.

Smear an oil dampened finger of wvo across a cool cast iron fry pan.

This will serve to indicate when the pan is reaching test temperature.

Keep the sample of wvo to be tested handy. Enough for 1/4"-3/8" thickness covering the bottom works best.
Heat the pan on medium high temp until the smear begins to produce smoke then pour in the sample.

Observe the sample where the oil contacts the pan surface. Very small bubbles forming on the pan/oil interface indicate suspended water in the sample.

The density of bubbles indicates how much water is present in suspended form.

Many large bubbles indicate the sample contains at leas 1000 ppm of water in the sample.

Many small bubbles indicate the sample contains 500-1000 ppm of water in the sample.

3-4 bubbles per square inch indicate 200-300 ppm of water in the sample.

1-2 bubbles per square inch indicate under 100 ppm of water in the sample.

If crackling or popping is heard..over 1000ppm of water is present in the sample.

Optimumly you want to use VO fuel that contains less than 100ppm of water for maximum injector pump and injector life.

NOTES:
Do not pour in a sample with any visible water.

If water droplets are visible no testing is needed. There is water present in your sample.

Visible droplets of water will spatter hot oil out of the pan and may cause burns or fire.

Do not average bubble count. The visibility of bubbles is dependent on the temp of the underlying pan and this may be regionalized depending on your heat source.

If the pan has been washed or not used previously it must be "seasoned" to make certain that no moisture is trapped in the pores on the surface of cast iron.

False positive results (bubbles) can be obtained if the pan is WAY too hot..or if solvents are mixed in the WVO.

False negative results (no bubbles) are possible if the suspended water has high concentrations of salt/sugar/ acids.

I have tried to keep this test as simple, cheap, and translatable as possible.

It works....though it is not "foolproof".

 


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