Biodegradable Hydraulic Fluids: A Review

Abstract

There is currently increasing interest in biodegradable hydraulic fluids. Such fluids are often considered to include only vegetable oils, polyol esters and diester base stocks. However, other fluid base stocks including highly refined mineral oils, poly (alpha olefin) and fire-resistant fluids such water-glycol hydraulic fluids are also biodegradable fluid alternatives. This paper will provide an overview of the international literature on biodegradable fluids, various international testing protocol, fluid base stocks, effect of oxidative stability, material compatibility and pump performance. From the literature available, an assessment of future directions in this ever-changing field will be provided.