5. Conclusion

Several methods for measuring the viscosity of gases and liquids have been carefully described. Particular attention has been paid to devices that allow simultaneous measurement of viscosity and density, with good accuracy. Capillary tube viscometers are the most widely used instruments for measuring liquid viscosity, due to their simplicity of construction and ease of use. A number of rotational viscometers are currently on the market. These devices not only measure viscosity, but also determine the rheological properties of materials. They should be used with caution, especially when the materials under consideration do not exhibit Newtonian behavior.

The viscosity of gases increases with temperature in a quasi-linear fashion within a small temperature range, e.g. between 300 K and 600 K. The viscosity of liquids decreases with increasing temperature. This decrease...