Kinematic viscosities appear to be loglog dependent on temperatures. Where w i = weight fractions of the components.Ĭoming back to your question, measure the viscosity at another temperature, and then extrapolate or intrapolate as needed to get the value at 100 oC. Ln visc blend = summation of (w i x ln visc i) with a 5-10% precision, There are charts for low and high viscosity ranges. One can also use the ASTM Standard Charts for Liquid Petroleum Products (D341) that give kinematic viscosities vs temperatures. The BP chart is helpful in making blends on a weight basis. The BP chart, for example, enables converting among various viscosities such as Redwwod I, Saybolt Universal and Saybolt Furol, all of them measured in seconds, to degrees Engler or to kin. You probably heard of paraffinic (high VI) and naphthenic (low VI) lubes. The VI or V/T dependence varies with chemical structure of the hydrocarbons. This is needed since the VI (viscosity index) of the fuels isn't known. In order to be able to find viscosities of fuels at various temperatures one needs to know two viscosities at two different temperatures.īy using charts such as the BP viscosity/temperature chart or the Refutas chart one can find the wanted value at other temps. There are various charts in the market to help you out.
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