What is in this article?:
Today's emphasis on pollution prevention and waste stream minimization has made the benefits of contamination control programs for hydraulic fluids even more compelling.
Concern for the environment has become a fact of life for most companies. For the companies that use hydraulic equipment, that concern is reinforced by stringent federal and local regulations requiring pollution prevention and governing disposal of used industrial fluids. Higher costs (and greater potential liabilities) for fluid disposal are a direct result of these regulations. This adds another economic item to the list of benefits derived from controlling contamination to extend the service life of hydraulic fluids. The list now includes:
- lower cost for fluid needed for replacement and replenishment
- more consistent hydraulic system performance
- less component wear, and
- reduced fluid disposal costs.
Contamination's detrimental effects
It is an established fact that particulate contamination and water in hydraulic fluids can have serious adverse effects on the fluids' physical and chemical properties. The loss of crucial fluid properties, which are central to useful service life, can result in inefficient system performance and accelerated mechanical and chemical wear processes.
Hydraulic fluids are carefully formulated for specific areas of application. They usually are comprised of a base stock and an additive package. The additive package consists of chemical compounds designed to protect the base stock - as well as the components in the hydraulic system - and to ensure proper performance of the system. Typical additives include dispersants and detergents; anti-oxidants; anti-corrosion, anti-wear, anti-foaming and extreme pressure (EP) agents; and viscosity-index improvers. Particulate contamination and water adversely affect both the base stock and the additives.
Water is a poor lubricant, and significant concentrations of water in hydraulic fluids can decrease their viscosity and load-carrying ability, as well as hydrodynamic-film thickness. This can lead to greater surface-to-surface contact at sliding and rolling dynamic clearances, and hence, increased component wear. The presence of free water in systems that could be exposed to temperatures below the freezing point of water can lead to icing, which will degrade system performance and can produce malfunctions.
The presence of both water and particulate contamination can lead to the formation of insoluble precipitates, and viscous sludges and gels. These materials induce excessive stress on system components - especially pumps - and can clog orifices, nozzles, and jets.