ASTM D341 Standard Practice for Viscosity-Temperature Charts
ASTM D341 Standard Practice for Viscosity-Temperature Charts for Liquid Petroleum Products
5. Procedure
5.1 Plot two known kinematic viscosity-temperature points on the chart. Draw a sharply defined straight line through them. A point on this line, within the range defined in Section 3, shows the kinematic viscosity at the corresponding desired temperature and vice versa.
5.2 Alternatively, the interpolated and extrapolated kinematic viscosities and temperatures may be calculated as described in Annex A1, within the range identified for the charts in Section 3.
6. Extrapolation
6.1 Kinematic viscosity-temperature points on the extrapolated portion of the line, but still within the range defined in Section 3, are satisfactory provided the kinematic viscosity-temperature line is located quite accurately. For purposes of extrapolation, it is especially important that the two known kinematic viscosity-temperature points be far apart. If these two points are not sufficiently far apart, experimental errors in the kinematic viscosity determinations and in drawing the line may seriously affect the accuracy of extrapolated points, particularly if the difference between an extrapolated temperature and the nearest temperature of determination is greater than the difference between the two temperatures of determination. In extreme cases, an additional determination at a third temperature is advisable.
7. Keywords
7.1 charts; kinematic viscosity; MacCoull; viscosity; viscosity-temperature charts
