On the basis of the refractive index the concentration of ethylenglycol or propylene glycol is determined. The glycol content primarily influences the thermal characteristics of a coolant.
As the concentration is linked to the additive content it considerably incluences the corrosion protection. Furthermore, it is possible to distinguish between ethylenglycol and propylene glycol with the density. A mixture with a third component can change the refractive index or rather the density. With the ethylenglycol concentration a theoretical freezing point can also be output.