The NF T66-020 test standard, canceled in 2002, describes a method for measuring the pseudo-viscosity of emulsions still used in certain French-speaking countries. An identical method, varying in a few technical details, is also described in standard ASTM D1665. In Europe, the method currently in force is that of the viscometer STV EN 12846.

The test consists of measuring the time taken by a specified quantity of emulsion (200 ml) to flow through an orifice of given size at a temperature of 25°C. This flow time is then divided by the flow time of the same volume of water under the same experimental conditions. The result is expressed in °E (Engler degree).

Standard NM 03.4.033 (Morocco) recommends the use of the Engler viscometer for viscosities up to 15°E. Beyond this, the STV viscometer must be used.

NF T66-020 – ASTM D1665 – NM 03.4.033