Petroleum and related products - Determination of the shear stability of polymer-containing oils using a diesel injector nozzle (ISO 20844:2015); German version EN ISO 20844:2015

2Scope / Description

This International Standard specifies a method for assessing the resistance of mineral oils, synthetic oils, and other polymer-containing fluids to shear stress when passing through a specified diesel injector nozzle. Shear stability is measured as the change in viscosity of the fluid under test resulting from polymer degradation under stress. This International Standard is generally applied to hydraulic fluids of categories HR and HV as defined in ISO 6743-4 and specified in ISO 11158; however, under adapted conditions according to ISO 12922, it may also be applied to fire-resistant hydraulic fluids of categories HFA, HFB, HFC, and HFD. No formal correlation has been established between viscosity loss or lack thereof when applying the methods of this International Standard and viscosity loss or lack thereof in oils and fluids in practical application. However, the method provides standardized conditions for assessing polymer stability under reduced thermal and oxidative stresses. It is commonly used by manufacturers of liquids and additives, as well as by users, as an aid in evaluating existing and potential formulations.