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Why are phosphate esters used in some hydraulic systems?

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motor oil — lubrication Motor oil, a lubricant for automobile engines.

Phosphate esters are utilized in specific hydraulic systems primarily because they provide excellent fire resistance.1

In the context of lubrication technology, synthetic lubricants are often chosen for their superior performance compared to traditional petroleum-based products. While petroleum lubricants are valued for their low cost and availability, synthetic materials like phosphate esters are specifically engineered to offer enhanced stability and safety in demanding environments.1

Beyond their fire-resistant properties, phosphate esters are also employed as low-temperature lubricants. These phosphate compounds are a class of synthetic materials that, unlike naturally occurring hydrocarbons, are designed to meet specialized operational requirements where safety and temperature stability are critical.12