Pan Test
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Summary
The "Pan Test" is a quick, unscientific and non-quantitative test to check for the presence of water in WVO.
It works, although it is not "foolproof" by any means. False positives can be obtained if the pan is WAY too hot or if solvents are mixed in the WVO. False negative results are possible if the sample contains suspended water that has high concentrations of salt/sugar/acids.
Procedure
Smear a finger of WVO across a frying pan (cast iron preferred) as a temp check.
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 high temp until the smear begins to really smoke then pour in the sample.
NOTE: 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 a fire.
Look closely at the bottom of the pan where the oil meets it. Are there very small bubbles forming? This indicates water is present in the WVO. The number of bubbles is a rough indicator of how much water is present.
"Acceptable" Water Levels
For the various standards and what is deemed acceptable, see Fuel Standards. Also see Filtering and Dewatering for more dewatering options.
Accuracy
SunWizard conducted tests using the Pan method and sent them off to be analyzed (tests sponsored by Dieselcraft) via Karl Fischer ASTM D6304 (couloumetric) (accurate to 1ppm.)
Sample #1 was the original VO, sucked from dumpster with 100 mesh screen.
Sample #2 was one pass though the centrifuge at 55-120F.
Sample #3 was heated, mistwashed and went six passes though the centrifuge at 120-180F.
He ran two pan tests on each sample, separated by several hours. The results of the pan test were:
- Sample #1 = lots of bubbles
- Sample #2 = no bubbles
- Sample #3 = no bubbles
The lab results from the samples analyzed via Karl Fischer ASTM D6304 (couloumetric) were:
- Sample #1 = 708ppm water
- Sample #2 = 545ppm water
- Sample #3 = 478ppm water
This shows the pan test does not detect water at or below 545ppm. From this test, it can only be stated that the pan test will usually detect water levels of 708ppm and higher.
