CCAI (Calculated Carbon Aromaticity Index)

The Calculated Carbon Aromaticity Index estimates the ignition quality of a residual marine fuel from its density and kinematic viscosity, because residual fuels are too dark and viscous for a measured cetane number. A higher CCAI signals a more aromatic, harder-to-ignite fuel that can cause ignition delay and combustion problems in the engine. ISO 8217 references it as an informative quality indicator, and engine makers set CCAI limits for the fuels they will guarantee.