TYPES OF FIRE-RESISTANT HYDRAULIC FLUIDS & THEIR IMPORTANCE

Lubrication holds significant importance in the metalworking industry. Effective lubrication is key to getting the best out of your machinery and ensuring its long operational life. A routine lubrication regimen offers several benefits during production and machine maintenance. While its core benefit is protection against corrosion and wear & tear, good lubrication practices can ensure the high-performance capabilities of machines in the long run. Since metalworking involves high-temperature environments, industries typically prefer hydraulic fluids. 

A hydraulic fluid or oil is the medium by which power is transferred in hydraulic machinery. These fluids are either mineral oil-based or water-based. Fire-resistant hydraulic fluids are often associated with hydraulic systems, where components operate at an extremely high temperature. Such working conditions will likely ignite the fluid and risk the entire operation. 

Characteristics of fire-resistant hydraulic fluids

While the primary purpose of fire-resistant hydraulic fluids is to avert ignition, these oils possess several other characteristics. An ideal hydraulic fluid should have

• Excellent lubricity
• Very high flash point
• Stability of fluids in service

Furthermore, these oils should guarantee a long lifetime of service and adequate protection for your equipment. 

Types of fire-resistant hydraulic fluids

Since hydraulic systems and their applications differ largely, different types of fire-resistant hydraulic oils are used. Let us take a look at some common hydraulic fluid types. 

• Phosphate esters fluids

Phosphate ester fluids possess excellent lubricity for hydraulic components. However, one must be cautious when handling or discarding this type of fluid. In fact, special seals and hoses must be used on all hydraulic components within the hydraulic system. That said, these fluids offer excellent fire-resistant properties. Previously, phosphate ester fluids were used in aircraft hydraulic systems, although they have fallen out of favour in recent years. 

• Water glycol fluids

Water glycol fluids offer excellent fire-resistant properties as it has high water content. However, when this fluid is subjected to high pressure, its protective film safeguarding hydraulic components gets affected by the poor lubricity of the water contained in the fluid.

• Oil-in-emulsion fluids

The creation of water-in-emulsion fluids involves mixing regular hydrocarbon hydraulic oil with water. These fluids require water from 35% to 45% to maintain their resistance to fire. Water in emulsion fluids must also be carefully monitored to ensure that water evaporation does not render the fluid combustible.

• Polyol ester fluids

In recent times, polyol esters have become the most widely used fire-resistant hydraulic fluid. They have excellent fire-resistant properties, great lubricity even under high pressure, and superior viscosity levels across a wide range of temperatures. As a result, these fluids can often be used with NBR (Buna) seals that are typically available.

• Oil-water emulsions

A fire-resistant oil-water emulsion comprises two components: an oil-in-water emulsion and an oil-in-oil emulsion. In oil-in-water emulsions, small amounts of oil dispersed in water are sustained. The general ratio of oil-to-water is 5:95 . The formulations provide excellent fire resistance and heat transfer. However, they lack lubricity and corrosion protection because of the water content. 

Final thoughts

Fire-resistant hydraulic fluids play a critical role in hydraulic systems, be it of any type. They can potentially prevent the ignition of the machine and extend its operational life. Thus, selecting the right fire-resistant type of hydraulic fluid is extremely essential. Castrol understands the importance of selecting the right hydraulic fluid for your fleet. And that’s why we offer a wide range of fluids designed to protect and improve the efficiency of your hydraulic machines. Our select range of products can improve oxidation stability to accommodate high operating temperatures, offer better hydrolytic stability to handle water contamination, and extend pump life to meet Denison T6H20C pump performance.