What are the types of fire-resistant hydraulic oil and what are the differences in performance?
March 20, 2022
Fire-resistant oil is commonly used in hydraulic system oil, and mineral oil cannot be used in applications with fire-resistant requirements. The International Organization for Standardization (ISO) divides fire-resistant hydraulic oils into four categories: HFA oil-in-water emulsion; HFB water-in-oil emulsion; HFC. HFA-oil-in-water emulsion It is a mixture of fine oil particles dispersed in water as a continuous phase, and is an emulsified water-based fire-resistant liquid with a water content of more than 80%. Its Base Oil is used as a carrier for various additives, and emulsifiers, rust inhibitors, mildew inhibitors, anti-foaming agents and cosolvents are added. Therefore, HFAE emulsion has high specific heat, good flame resistance, excellent cooling performance, cheap and harmless to human body. The anti-rust and anti-corrosion ability of metal materials can be improved as required. Good adaptability to general non-metallic materials. Because it is an aqueous liquid, with high vapor pressure and poor lubricity, the operating temperature cannot exceed 50°C, and the system pressure cannot exceed 7.0MPa. It is suitable for hydrostatic hydraulic system of coal mine hydraulic support and other hydraulic systems or mechanical parts that do not require recycling waste liquid and do not require good lubricity, but require good flame retardant liquid.
HFA - High Water Base Fluid Usually consists of 95% water and 5% water-soluble chemicals. It is non-flammable, non-compressible, has high heat capacity and thermal conductivity, and has good cooling effect. The system operating temperature is usually lower than the oil system. Low viscosity, fast dirt precipitation, cheap (only 1/5 to 1/10 of the cost of mineral oil), non-toxic, non-polluting, and easy to handle. The best use temperature is 4 ~ 50 ℃, if the temperature is too low, it may freeze, and if the temperature is too high, the evaporation is too fast. The lubricity of water is poor, so the system pressure it operates cannot be higher than 7.0MPa. In addition, it is not compatible with aluminum, magnesium, lead, zinc, galvanized steel (material), cadmium metal materials, and cork, paper, butyl rubber, leather, most paints and coatings. Pay attention when using it. Suitable for low-pressure hydraulic systems and metalworking machinery that require inflammable liquids. HFB-water-in-oil emulsion It is composed of 60% mineral oil and 40% water, fine water particles are dispersed in the continuous phase of mineral oil, and water is the flame retardant component. The lubricating properties of water-in-oil emulsions are relatively low compared to mineral oils, which limits their use in high-pressure systems. Due to water content and high vapor pressure, its maximum temperature cannot exceed 65°C. One of the main problems with water-in-oil emulsions in use is stability. Long-term standing, high temperature and pollution will cause phase separation, and the appearance of phase separation accelerates the premature damage of the pump. The main advantage of water-in-oil is the ability to use the same non-metallic materials as mineral oil, including seals, hoses, and coatings. Except for magnesium, it is compatible with general metal materials. Suitable for medium and high pressure, high temperature and flammable systems in metallurgy, coal mining and other industries. HFC-water-glycol solution It is also a fire-resistant hydraulic fluid with water as a fire-resistant component. It is composed of 30-55% water and 25-45% ethylene glycol, glycerol or its polymers, as well as water-soluble thickeners, anti-wear agent, rust inhibitor, Anti-foaming Agent, etc. The liquid has excellent flame resistance, high viscosity index, good stability and fluidity, and is a transparent true solution. The operating temperature cannot exceed 65°C, and it is generally used in systems with a pressure not higher than 10MPa. It can use the same sealing materials and hoses as mineral oil, but it is different from zinc, cadmium, magnesium, silver and untreated aluminum. Compatible, also can not use leather and cork, can soften ordinary paint, can only be used on epoxy-based paint or vinyl paint. Ethylene glycol has certain toxicity and should be prevented from entering the mouth, but it does not cause harm to the body. Low and medium pressure hydraulic systems for industries such as metallurgy and coal mining.
HFD-Phosphate Ester Synthetic Fire Resistant Hydraulic Fluid The fluid has high auto-ignition point, low volatility, good flame resistance and lubricity comparable to the best mineral oils. Compatible with most metal materials. Because of its high polarity and strong solubility, it is not suitable for general non-metallic materials such as nitrile rubber, neoprene rubber, asbestos rubber sheets, polyvinyl chloride plastics, plexiglass and vinyl coatings that are usually suitable for mineral oil. Carefully select matching materials. The operating temperature range of phosphate ester is -50~135℃, and it is suitable for hydraulic systems operating under high temperature and high pressure such as metallurgy, thermal power generation, and gas turbine oil. Mainly used in aircraft hydraulic systems and high temperature and high pressure hydraulic systems near high temperature heat sources or open flames. HFDS - Chlorinated Hydrocarbon Anhydrous Synthetic Liquid HFDT-anhydrous synthetic fluid mixed with chlorinated hydrocarbons and phosphate esters There is no production of these two types in my country. HFDU fluid For other anhydrous synthetic liquids, the performance of this variety is not very clear at present.
