How is the viscosity of oil determined?
Oil viscosity can be determined by various methods. The most widely accepted practice is to follow an ASTM method such as D445 or D7483 which are based on capillary and oscillating piston viscometers respectively. The capillary viscometer measures the time for a fluid to flow between two points in a glass capillary that has been placed in a temperature controlled bath. The oscillating piston method, sometimes referred to as Electromagnetic Viscometer or EMV viscometer, uses a sensor comprised of a measurement chamber and magnetically influenced piston. Measurements are taken whereby a sample is first introduced into the thermally controlled measurement chamber where the piston resides. Electronics drive the piston into oscillatory motion within the measurement chamber with a controlled magnetic field. A shear stress is imposed on the liquid (or gas) due to the piston travel and the viscosity is determined by measuring the travel time of the piston. The construction parameters for the a
