The complete guide for using fire-resistant hydraulic fluids
Fire-resistant fluids are most often associated with hydraulic systems. In this guide, we have compiled criteria for choosing a fire-resistant lubricant.
Lubrication is an essential aspect of the demanding metal-working industry. Effective lubrication provides machinists with several benefits during production and machine maintenance. A lubricant's core benefits are protection against corrosion and wear, dissipating heat from hot zones and transferring heat to contaminants. Selection of the ideal lubricant is crucial in the metal-working industry as metal components operate under high pressures and temperatures. A majority of the lubricants are flammable under specific conditions. This is due to the properties derived from the lubricant's base oils. For this reason, industries operating in high-temperature environments prefer fire-resistant hydraulic fluids. In this guide, we have compiled a checklist to see if your industry requires a fire-resistant lubricant.
Criteria for choosing a fire-resistant lubricant:
1) Working conditions
There is always a risk of fire when equipment operates with a lubricated component. The risk of fire increases significantly when the lubricant in use has a low flash point and is close to the ignition source or hot surfaces.
If lubricants are pressurized in their application, such as in hydraulic lines, it increases the risk of small leaks and the possibility of a spray of lubricant being atomized in the air. Frequent small leaks of lubricant sprays can result in component failure. Such leaks also increase the risk of a fire that can lead to serious injury to the employees and even death in catastrophic scenarios. Opting for fire-resistant lubricants with higher fire points reduces the risk of death and damage.
2) Fire-resistant fluid standards
Hydraulic fluid types as classified within the ISO 6743-4:2015 standard. The six categories of lubricants with fire-resistant properties are HFAE, HFAS, HFB, HFC, HFDR, and HDFU.
3) Types of fire-resistant hydraulic fluids
A. Oil-water emulsions
The two types of fire-resistant oil-water emulsions are oil-in-water and water-in-oil. Oil-in-water emulsions are formulated to sustain small amounts of oil dispersed in water. The general ratio of oil:water is 5:95 . These formulations offer superior fire-resistance and heat transfer capabilities. However, they lack lubricity and corrosion protection because of the water content.
Water-in-oil emulsions, popularly known as inverse emulsions, are formulations where the oil is in the majority. The ratio of oil to water in these formulations is generally 60:40. Water-in-oil emulsions offer good fire-resistant properties and excellent heat transfer capabilities. These lubricants provide higher lubrication than oil-in-water formulations. When exposed to heat, the water in the emulsion turns to steam and reduces the oil’s flammability.
B. Water-glycol solutions
These emulsions are formulated with 60% glycol and 35% water. Glycol-based formulations have a lower freeze point, with the water providing fire-resistant properties. This lubricant can be incompatible with other fluids, paints and coatings.
C. Phosphate esters Phosphate esters have superior fire-resistant properties out of all fluids. Their natural molecular structure enables them to have excellent fire-resistance, anti-wear characteristics, and oxidative stability.
D. Polyol esters Polyol esters have excellent fire-resistant and lubrication properties. They also offer good viscosity stability over a wide range of temperatures.
4) Considerations during changeovers
A lubricant changeover in any application should be carried out carefully by considering the degree of cross-compatibility and the remaining amount of residual fluid in the working system.
Draining the fluid while the system is warm makes it convenient to remove fluid from every corner of the system.
Replacement of filters with leftover lubricants is essential for synthetic-based fluids.
Conclusion:
Selection of the ideal fire-resistant type of hydraulic fluid is essential to decrease the risk of damage and death and to provide a safer working environment for employees. Choosing a fire-resistant hydraulic fluid from a dependable manufacturer is essential for peace of mind. Castrol is one of the most reputed liquid engineering companies globally. Our products are formulated after thoroughly researching the industry requirements for maximum efficiency. Our range of fire-resistant hydraulic fluids provides a safe working environment, improved system reliability and biodegradability.