Hydraulic Oils Classification
Hydraulic Standard Fluids
Composition | ISO Classification | Applications |
|---|---|---|
| Rust & Oxidation | ISO-L-HL | Recommended where pressures are not very high and pump performance is less than maximum and therefore loads are low. |
| Antiwear | ISO-L-HM | Recommended for pumps operating at high pressures or close to maximum performance, or when recommended by the OEM. |
| Antiwear, low temperature and viscosity modifiers | ISO-L-HV | HM type lubricants but with a high viscosity index. |
| Hydraulc with anti-stick slip properties | ISO-L-HG | Machine tool slideways have special lubrication requirements, because they move slowly but with large forces applied between the moving surfaces. |
| Mineral oils | ISO-L-HH | Only in systems such as manual hydraulic jacks or systems that are prone to high and costly oil leaks. |
Biodegradable Hydraulic Fluids
Composition | ISO Classification | Applications |
|---|---|---|
| Vegetals oils | ISO-L-HETG | These oils, together with carefully selected additives, are ideal in agriculture when contact with crops is unavoidable. |
| Synthetic esters | ISO-L-HEES | Reaction between alcohols and acids. They are used when hydrolytic stability, compatibility with sealing elements and low temperatures are needed. |
| PAG - water soluble | ISO-L-HEPG | The solubility of these materials is ideal in systems where there may be contact with water. Example: hydraulic engineering or water purification plants. |
| PAO and related | ISO-L-HEPR | Insoluble in water and not recommended for working in these environments. |
Fire-Resistant Hydraulic Fluids
Composition | ISO Classification | Applications |
|---|---|---|
| Water | - | Additive-free water is used in sensitive applications such as freshwater or marine environments. |
| Oil-in-water emulsions | ISO-L-HFAE | Fluids with high vapor pressure, this circumstance can happen due to suction cavitation. |
| Synthetic water-based concentrates | ISO-L-HFAS | Not very well positioned in the market, minerals still predominate. |
| Water-in-oil emulsions | ISO-L-HFB | As in all fluids that incorporate water, manufacturers recommend working at lower pressures and discharges than with mineral oils. |
| Water-Glycol | ISO-L-HFC | Low wear protection compared to mineral oils, not very suitable for pumps with rolling element bearings or for working at high pressures. |
| Water free fluids - Phosphoric esters | ISO-L-HFDR | Used in industrial applications as controlling and regulating fluids in turbines and as hydraulic fluids for aviation. |
| Water free fluids - other compositions | ISO-L-HF | Stable to oxidation, used in hydraulic systems operating at high temperatures and pressures. Good wear protection. |