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.
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".