Sciencemadness Discussion Board

How to check fuel quality for octane & cetane ratings & possibly ethanol & water contamination

RogueRose - 28-5-2022 at 19:33

I'm trying to come up with a fairly easy method where I can test gasoline or diesel to see if it is any good, tell what grade gasoline it is (and ideally if it has ethanol & howw much) and also test diesel fuel (IDK whatt kind of tests I would need for this, possibly ultra-low sulfur, biodiesel, kerosene or heating oil, etc.

Ideally the test would be as simple as possible and quick (faster the better, but up to maybe 60 mins would be tolerable).

I have a job that handles many thousands of cars a week, many with completely full tanks and many of the tanks are 35-50 gallons for primary tank & 25-40gal for an aux tank (for "personal SUV & trucks). Then there are the BIG trucks which might have 100-150 gallons.

So, I'd like to be able to test the gas to see if it's "regular" or up to premium or ultra & if diesel, is there any problem, contamination, etc.

I would probably need to do 200+ tests a day, maybe up to 500-1000+, but that would just be the person doing the actual testing (handed a sample - maybe 3-50ml of the fuel to test) & depending on the results will determine where we go from there.

Rainwater - 29-5-2022 at 09:39

Water and ethanol are very very easy to test for.
The problem will be collecting a proper sample. The sample must be taken from the lowest point in the storage tank, regardless of size.

For a nonaviation vehicle, this is most easily done using the existing fuel line.
Place the sample into a graduated cylinder. If water is present it will form the bottom layer.

Special agents are added to ethanol containing fuels to prevent the ethanol from moving into an aqueous solution. Not sure what these chemicals are but by trade we just call them "phase separation inhibitors". They basically saturate the water so the ethanol doesn't want to enter it.

With a known sample of fuel (100ml) add to it a 50% volume of water. (150ml total) then shake.
If no ethanol is present you will see an aqueous layer from 0-50ml then a fuel layer from 50-150ml
If ethanol is present it will move into the aqueous layer. So you will see, for example, an aqueous layer from 0-60ml and 60-150ml fuel.

Most areas in the usa dye the fuel different colors for different grades. High sulfur diesel is, to the best of my knowledge, the only nationwide standard colored red.
The colors are usually determined by the refinery which shipped the fuel

Edit: forgot the last point. If you would like. I can provide you with the apc certified company I use for detailed fuel testing. They do charge per sample with a 3-5 day turnaround time. But for the situation, as described, I do not believe that would be a viable solution. In addition to them only servicing Georgia and Florida


[Edited on 29-5-2022 by Rainwater]