ABSTRACT
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There are several ways in which hydraulic oils are classied or described for marketing purposes. The two major class descriptions for hydraulic –uids are based upon the majority ingredient, the base –uid. These classes are mineral oils and synthetics. As a general class, mineral oil hydraulic –uids are the most common hydraulic –uids used in the –uid power industry. The main reasons for this include: tradition, comparative low cost, availability, good viscosity and viscosity-pressure properties, excellent lubricity, suitability for high temperature use, metal and seal compatibility, and resistance to corrosion. Disadvantages of mineral oil hydraulic –uids include: –ammability characteristics, low biodegradability and ecotoxicity problems when leaked into open water or underground aquifers, poor compatibility with metalworking formulations, and-in some cases-poor viscosity-temperature properties when used over a broad temperature range [1].
