Comment:
Typically, the ash value is in the range 0.03-0.07% m/m. The figure is a histogram of world-wide residual fuel ash levels.
See also Section 2.10 Vanadium and Sodium
Info Centre >> Fuel and Lube Oil Technical Manual >> 2. Fuel Oil - Characteristics >> 2.7 Ash
The ash value is related to the inorganic material in the fuel oil. The actual value depends upon three factors, firstly the inorganic material naturally present in the crude oil, secondly the refinery processes employed, and thirdly, upon possible subsequent contamination due to sand, dirt and rust scale.
The ash level of distillate fuels is negligible. Residual fuels have more of the ash-forming constituents as they are concentrated in the residue from the crude oil refining processes. Vanadium and other materials such as silicon, aluminium, nickel, sodium and iron are the main contributing components.