In accordance with DIN ISO 15380, biodegradable hydraulic fluids are divided into different product groups depending on their composition, for which group-specific requirements are defined (see table).
| Group | Base oil |
| HETG | Triglycerides (e.g. rapeseed or sunflower oil) |
| HEES | Synthetic esters |
| HEPG | Polyglycols |
| HEPR | Polyalphaolefins and related |
In addition, manufacturers of biodegradable hydraulic fluids can have their products certified in accordance with European or national regulations.
The EU Ecolabel has established itself in Europe, while the Blue Angel ecolabel continues to apply in Germany. Awarding these ecolabels ensures that hydraulic fluids meet the minimum requirements of DIN ISO 15380 as well as the additional requirements of the responsible national or international authorities.
In the current edition, the EU Ecolabel does not define any obligation to use renewable raw materials. However, in accordance with ASTM D6866, the current edition of DIN ISO 15380 (2024-10) has introduced a minimum proportion of 25% of raw materials of biological origin for the HEES (synthetic ester fluids) and HETG (triglycerides, based on e.g. rapeseed or sunflower oil) product groups.
In concrete terms, this means that biodegradable hydraulic fluids that met the requirements of the HEES group according to the previous edition of DIN ISO 15380 can no longer be designated as “HEES in accordance with DIN ISO 15380” if they do not contain the required proportion of biogenic components. This affects many commercially available products.
In addition, fluids from the HEPR group (PAO base fluid or similar) are currently available that meet the requirements of the EU Ecolabel, including biodegradability. However, no requirements for the use of raw materials of biological origin are defined in this group.
As a result, this has given rise to the following situation:
- Ester fluids that fully meet the requirements of ISO 15380, except for the requirements regarding the use of raw materials of biological origin, may no longer be designated HEES.
- HEPR fluids, on the other hand, are allowed even though they do not contain any raw materials of biological origin.
Ultimately, this is a situation that raises questions not only from end users. It remains to be seen whether there will be any further adaptations here in the future.