I have noted on some threads that members sometimes refer to the pH and specific gravity of their finished product.
Can someone please tell if these are indicators to the quality of the BD and if so, what should we be aiming to achieve on their respective scale of measurements.
Using a fairly basic means of determining the SG of my product I have come up with a reading of 0.87 but I do not know whether this is good or bad.
I would like to know how to test the pH of BD. I understand a swimming pool test kit is not suitable. Is litmus paper the answer and if so would it give a reliable reading?
Look forward to your usual good advice
Drover

Hello Drover

The pH of biodiesel is meaningless.
I have never heard of biodiesel made to such a low standard that it did not meet the required SG.

Both tests have no meaning for biodiesel production

Biodiesel cannot have a pH as it is not an aqueous solution. It could have an "Acid Number" which relates to residual caustic in the biodiesel (IIRC). This has not been shown to have any impact on the fuel system unless there is water in the fuel. People who wash the biodiesel should have a very low acid number as most, if not all, caustic will have been removed in the first 2 washes.

SG is the density of the biodiesel (weight compared with water - for the same volume) and has no valuie in determineing the quality of the fuel. It may vary because of the feedstock or if residual methanol is present in the biodiesel. It is of no consequence.

Melting point and conversion are the 2 tests which tell us most about biodiesel.
the first can be done using a fridge/Freezer and a thermometer and the second can be done using 27mL of methanol and 3 mL of the biodiesel.

I hope this helps,
Tony

Thank you Tilly and Tony, you have both been awesome with your prompt and meaningful replies.
I obviously have a lot to learn still but I am sure I am now on the right track.
Drover.