4. Viscosity standards

The provision of viscosity standards for industry is of paramount importance, as viscosity is a key parameter in the measurement of flow velocities, in the calculation of heat transfer coefficients and in the control of chemical reactions. Since Poiseuille first measured viscosity, establishing viscosity standards for gases and liquids has proved an extremely difficult task. These standards can be used to verify the reliability of a new measurement method or device, and are also indispensable for calibrating viscometers for relative measurements. While an absolute determination of viscosity is difficult and complicated, a relative measurement is often much simpler to achieve.