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In previous discussions, we explored the advantages and drawbacks of using mineral oils and water-glycol solutions for high-pressure die casting machines. While both have their merits, there is another option that stands out for its balance between performance and fire resistance—HFDU oils. These synthetic hydraulic fluids are particularly well-suited for high-pressure hydraulic fluid applications, offering a robust solution in industrial settings. Let’s delve into why HFDU oils could be the superior choice for those looking for nonflammable hydraulic fluid options.
Key Takeaways
- HFDU oils are synthetic, fire-resistant, and water-free hydraulic fluids ideal for high-pressure systems.
- Offer high viscosity stability, superior pump protection, and excellent rust and oxidation resistance.
- Perform well under extreme pressure (up to 400 bar) and high-speed conditions.
- Last 4–5 times longer than mineral or water-glycol fluids, reducing maintenance costs.
- Require proper moisture (<2,000 ppm) and particulate control (NAS Class 9) for optimal performance.
- Balance fire safety and high performance, making them ideal for metalworking and die-casting industries.
What are HFDU Oils?
HFDU oils, known for their synthetic, anhydrous (non-water containing) nature, offer significant benefits over traditional hydraulic fluids. Formulated with a mix of organic and inorganic esters along with performance-enhancing additives, these fire-resistant hydraulic oils are designed to excel in demanding environments.
Key Properties of HFDU Oils
Higher Viscosity Index
One of the key benefits of HFDU oils is their high viscosity index, which allows them to maintain a wear-reducing lubricating film even at elevated temperatures. The ability to keep a consistent viscosity across varying temperatures reduces wear and tear on the equipment, ensuring longer-lasting performance and reducing the risk of costly downtime. In this regard, HFDU oils outperform traditional mineral oils and high-pressure hydraulic fluid options, such as water-glycol fluids, which tend to have lower viscosity stability under such conditions.
Rust and Corrosion Protection
HFDU oils offer excellent protection against rust and corrosion for both ferrous and non-ferrous metals. While mineral oils are effective in providing rust protection, HFDU oils perform at the same level, if not better. They significantly outperform water-glycol fluids, which are known to cause corrosion over time due to their water content.
Improved Pump Protection
Hydraulic systems rely heavily on pumps to maintain fluid pressure, and pump wear is a major concern for any system operator. HFDU oils excel in protecting pumps from wear and tear, as demonstrated by results from tests such as the Vickers Vane V104C. These tests have shown that HFDU oils provide better pump protection than mineral oils and water-glycol solutions. This improved protection leads to longer pump life and lower maintenance costs, making HFDU oils a cost-effective solution in the long term.
Resistance to Oxidation
HFDU oils have a significant advantage over other hydraulic fluids when it comes to oxidation resistance. Their formulation allows them to resist the formation of acids that accelerate oxidation, which is a common cause of oil degradation. Field data suggests that HFDU oils can last up to four or five times longer than mineral oils or water-glycol solutions. This extended lifespan not only reduces the frequency of oil changes but also lowers the overall maintenance burden on the system.
Performance Under High-Pressure and High-Speed Conditions

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One of the most compelling reasons to choose HFDU oils is their ability to perform under extreme conditions. They can operate at pressures up to 400 bar and are designed to handle the high speeds of modern hydraulic pumps. This contrasts with water-glycol fluids (HFCs), which are often limited by lower pressure and speed ratings.
Fire-Resistance Capabilities of HFDU Oils
While HFDU oils are not as fire-retardant as water-based HFCs, they still meet essential fire resistance standards, such as those set by Factory Mutual (FM). This makes them a safer choice for industries where fire hazards are present, without sacrificing the overall performance required by hydraulic systems. In this regard, HFDU oils strike an ideal balance between fire resistance and operational efficiency, making them a preferred option for industries like metalworking and die casting.
Handling and Maintenance of HFDU Oils
Proper handling and maintenance of HFDU oils are critical to ensure their optimal performance.
- Moisture Control: It is vital to keep moisture levels below 2,000 ppm, as excessive water can react with HFDU components to form harmful acids.
- Particulate Control: Solid particulates must also be controlled, with NAS Class 9 being the recommended upper limit. Maintaining these standards ensures the long-term reliability and performance of your hydraulic systems.
Conclusion
In summary, HFDU oils are an excellent option for high-pressure die casting machines, offering a unique combination of performance, fire resistance, and durability. For industries requiring high-pressure hydraulic fluid solutions, HFDU oils provide a superior alternative to traditional mineral oils and water-glycol fluids.
Discover the Benefits of HFDU Oils for Your Hydraulic Systems
To learn more about fire resistant hydraulic oils and find the right solution for your hydraulic systems, contact Fluid Solutions, a leading hydraulic supplier in the Philippines. We offer plenty of hydraulic fluid options, including HFDU oils. You may reach us at (02) 8370 5928 / (0917) 894 9156, or via email at inquiry@fluidsolutions.com.ph.