What are fire-resistant hydraulic oils and how are they classified?
Posted by Hamid Shakouri on 3rd Sep 2024
Fire-resistant hydraulic oil is specially formulated to prevent or minimize the risk of fire in hydraulic systems, especially in environments where the risk of fire or explosion is high. These oils are used in hydraulic systems that operate under high temperatures or where there is a potential for exposure to flames or sparks.
There are several types of fire-resistant hydraulic oils:
- Water-containing Fluids: These include water-containing fluids like water-containing phosphate esters and water-containing alkyl phosphates. They have a high water content, which helps to extinguish or suppress flames.
- Water-containing Phosphate Esters: These have a high flash point and are effective in cooling and extinguishing fires.
- Water-containing Alkyl Phosphates: Similar to phosphate esters but with different chemical properties.
- Non-water-containing Fluids: These do not contain water but have high fire-resistant properties.
- Phosphate Esters: These have a high fire point and are used in high-temperature operations.
- Organic Esters: These include esters derived from organic acids and alcohols and are used in various applications.
- Fluorocarbons: These are resistant to fire and have a high flash point, but they can be more expensive.
Fire-resistant hydraulic oils are crucial in industries such as mining, metallurgy, and manufacturing, where machinery operates in high-temperature environments. They help in reducing the risk of fire-related accidents and ensuring the safety and reliability of hydraulic systems.
| Classifications | Properties |
| HFAE: Oil in water emulsions | The water content exceeds 80% and is blended with a concentrate, either mineral oil or a soluble polyglycol-based solution. However, using a mineral-oil-based concentrate carries the risk of separation and potential microbe growth (referred to as the diesel bug). Notably, this mixture is flame-resistant and suitable for use within a temperature range of +5°C to +55°C |
| HFAS: Synthetic concentrates dissolved in water | There is no risk of separation, as this forms a true solution. However, it's important to note that this characteristic makes the hydraulic components more susceptible to corrosion |
| HFB: Water in oil emulsions | The water content surpasses 40% and is combined with mineral oil, forming an emulsion that is infrequently utilized. Despite its limited use, this emulsion is flame-resistant and can be employed at temperatures ranging from +5°C to +60°C. However, it's worth noting that in Germany, HFB fluids are not permitted due to their lack of fire protection properties |
| HFC: Water glycols | The water content in this polymer solution exceeds 35%. It is flame-resistant and suitable for use within a temperature range of -20°C to +60°C. Additionally, it can be utilized at pressures of up to 250 bar. |
| HFD: Synthetic liquids | HFD-R: Phosphoric esters ✅ HFD-S: Anhydrous
chlorinated hydrocarbons ✅ HFD-T: Mixture of HFD-R and HFD-S ✅ HFD-U: Anhydrous other
composition (consisting of fatty acid esters)
Synthetic liquids, excluding HFD-U, possess a higher density than mineral oil or water. This characteristic can potentially lead to issues with the suction performance of pumps and may impact various gasket materials. However, these liquids are flame-resistant and can be utilized within a temperature range of -20°C to +150°C |
