ISO/TC 28/SC 4/WG 3 - Joint ISO/TC 28/SC 4 - ISO/TC 131 WG: Classification and specifications of hydraulic fluids

This document specifies the minimum requirements of unused fire-resistant and less flammable hydraulic fluids for hydrostatic and hydrodynamic 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 these less hazardous fluids and to the manufacturers of hydraulic equipment in which they are used. Of the categories covered by ISO 6743-4, which classifies the different types of fluids used in hydraulic applications, only the following are detailed in this document: HFAE, HFAS, HFB, HFC, HFDR and HFDU. Types HFAE, HFAS, HFB, HFC and HFDR are "fire-resistant" fluids as defined by ISO 5598. Most HFDU fluids, while displaying an improvement in combustion behaviour over mineral oil, fall outside this definition and are more appropriately considered as "less flammable" fluids.

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).

ISO 6743-4:2015 establishes the detailed classification of fluids of Family H (Hydraulic systems) which belong to class L (Lubricants, industrial oils, and related products). It is intended to be read in conjunction with ISO 6743‑99. This classification system does not include automotive brake fluids or aircraft hydraulic fluids.

ISO 7745:2010 specifies the operational characteristics for the various categories of fire-resistant fluids defined by ISO 6743-4. ISO 7745:2010 details the factors to be considered when selecting a fluid from these categories for a proposed application. ISO 7745:2010 identifies difficulties which might arise from the use of such fluids and indicates how they may be minimized. Appropriate procedures are given for replacing one fluid with another from a different category. Health and safety aspects when handling and disposing of fire-resistant fluids are also covered. ISO 7745:2010 does not apply to fire-resistant fluids used in the hydraulic systems of commercial or military aircraft. The appropriate aviation standards are also usually applied where aircraft hydraulic fluids are filled into ground-based systems.

ISO 11158:2009 specifies the minimum requirements for new mineral oil hydraulic fluids and is intended for hydraulic systems, particularly for hydrostatic hydraulic fluid power application. The purpose of ISO 11158:2009 is for the guidance of suppliers and end users of mineral oil hydraulic fluids and for the direction of equipment manufacturers of hydraulic systems. ISO 11158:2009 is written in a general form so that its application can accommodate various climatic conditions throughout the world. ISO 11158:2009 also stipulates the requirements for mineral-oil hydraulic fluids at the time of delivery. Classification of fluids used in hydraulic applications is defined in ISO 6743-4. Of the categories covered by ISO 6743-4, only five types of mineral oil based fluids are embraced in ISO 11158:2009. These categories are HH, HL, HM, HV and HG.

ISO 12922:2012 specifies the minimum requirements of unused fire-resistant and less-flammable hydraulic fluids for hydrostatic and hydrodynamic 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 these less hazardous fluids and to the manufacturers of hydraulic equipment in which they are used. Of the categories covered by ISO 6743-4, which classifies the different types of fluids used in hydraulic applications, only the following are detailed in this International Standard: HFAE, HFAS, HFB, HFC, HFDR and HFDU.

ISO 15380:2011 specifies the requirements for environmentally acceptable hydraulic fluids. It is applicable to 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 to advise manufacturers of hydraulic systems. ISO 15380:2011 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 15380:2011 encompasses only four of the categories of environmentally acceptable fluids covered by ISO 6743-4. These categories are HETG, HEPG, HEES and HEPR.

This International Standard 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. This International Standard 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. Of the categories covered by ISO 6743-4, only four types of environmentally acceptable fluids are embraced in this International Standard. These categories are HETG, HEPG, HEES and HEPR.

Provides guidelines detailing, for the various categories of fluids, operational characteristics, advantages and disadvantages, and the factors affecting the choice to be made amongst these various categories. Specifies also precautions which should be adopted to reduce difficulties arising from the use of such fluids, as well as the precautions which are necessary when replacing fluids with fluids from different categories. The installation of hydraulic circuits with respect to fire-resistant fluids is also described.