ISO 15380:2016 specifies the requirements for environmentally acceptable hydraulic fluids and is intended for hydraulic systems, particularly hydraulic fluid power systems. The purpose of this International Standard is to provide guidance for suppliers and users of environmentally acceptable hydraulic fluids and for the direction of original equipment manufacturers of hydraulic systems.ISO 15380:2016 stipulates the requirements for environmentally acceptable hydraulic fluids at the time of delivery.Classification of fluids used in hydraulic application is defined in ISO 6743-4. ISO 15380:2016 encompasses only four of the categories of environmentally acceptable fluids covered by ISO 6743-4. These categories are HETG, HEPG, HEES and HEPR. The minimum content of base fluid for each category shall not be less than 70 % (m/m).