This International Standard specifies the requirements of fire-resistant hydraulic fluids for hydrostatic and hydrodynamic hydraulic systems in general industrial applications. It is not intended for use in aerospace or power generation applications, where different requirements apply. It provides guidance for suppliers and end users of fire-resistant hydraulic fluids and also direction for equipment manufacturers of hydraulic systems. This International Standard is written in a general form so that its application can accommodate various climatic conditions throughout the world. It also stipulates the requirements of fire-resistant hydraulic fluids at the time of delivery. ISO 6743-4 establishes the classification of fluids used in hydraulic applications. Of the categories covered by ISO 6743-4, only the following are detailed in this specification: HFAE, HFAS, HFB, HFC, HFDR and HFDU. NOTE For the purposes of this International Standard, the expressions "% (m/m)" and "% (V/V)" are used to represent respectively the mass fraction and the volume fraction of a material.