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Wednesday, 17 October 2012

What are fire resistant oils?

Are fire resistant oils for real? Where are they used?

When we refer to fire resistant oils we’re not really talking about those crash and burn accidents we see in the movies: No fire resistant oils are more commonly used in hydraulic applications.

What are fire resistant oils?

First discovered in the 1940’s phosphate esters have since been applauded by industry for their anti-wear and flame resistant properties.

Phosphate esters are used primarily as basestock
in several fire resistant oils including hydraulic fluid, turbines and compressors.

The first commercial products were synthesized from coal-tar derivatives and were consequently a mixture of various isomeric aryl phosphates, including the hazardous neurotoxic orthotolyl phosphate.

However, today, phosphate esters are synthesised from other raw materials. Modern technology allows better control of the manufacturing process, and the toxicity of the final product is normally low.

Their high ignition temperatures, excellent oxidation stability and very low vapor pressures make them difficult to burn, while their low heats of combustion result in self-extinguishing fluids.

Other uses for phosphate ester-based products.

Numerous organic phosphorus compounds including phosphites, phosphonates and phosphates have found application as additives in a variety of lubricant formulations as stabilizers, anti-wear additives, antioxidants, metal passivators and extreme-pressure additives.

Of these, zinc dialkyl dithiophosphates (ZDDP), found in virtually all automotive engine lubricants, are the most widely used. Only one group of phosphates, the tri-substituted natural esters of H3PO4, has found significant use as a synthetic basestock.

Phosphate ester-based fire resistant hydraulic oils

Although inhibited phosphate esters possess excellent oxidation stability and inherently good anti-wear properties under critical loading conditions, they suffer from somewhat inferior hydrolytic stability, low viscosity index and extreme chemical aggressiveness toward many conventional seal and coating materials.

These weaknesses limit the use of phosphate ester to specialized applications where a high degree of fire resistance is required.

Maintenance of a Phosphate Ester System

The user of fire resistant oils must accept the need for greater vigilance with respect to fluid maintenance than is normal for conventional mineral fluids. No longer is it sufficient to periodically change filters, repair the occasional leak and top off the reservoir. On average, phosphate esters cost five times more than their mineral counterparts.

The majority of fire resistant oils display a considerably greater degree of detergency than mineral fluids. Consequently, dirt particles or wear debris do not settle out in the sump as readily. This tendency promotes abrasive wear of pumps and other components along with affecting valve function.

If you’re not sure whether your plant and equipment require fire resistant oils then you need to speak to Habot Synthetic Lubricants – we’re the professionals in our field.