Environmental approach to hydraulic fluids

ABSTRACT Over the past years, contradictory information about ‘bio‐oils’ and ‘fast biodegradable hydraulic oils’ has been spread in the media and in the public. There are norms and standards that define the environmental requirements of environmental‐compatible hydraulic fluids. A key criterion in all of these standards is ready biodegradability, but testing biodegradability of poorly water soluble products is difficult. However, how important is fast biodegradability in the environment? Degradation needs oxygen. In sewage treatment plants, there is much oxygen due to an artificial supply, but in the environment, there is often a lack of oxygen, e.g. the biodegradation of 1 kg oil needs the oxygen that is dissolved in 400.000 l of water. If a fast biodegradable substance gets into an ecosystem, nature has to cope with oxygen deprivation. In the following review article we will summarise the present understanding of an environmental‐compatible hydraulic fluid, from a holistic point of view. Copyright © 2012 John Wiley & Sons, Ltd.