There is a wide range of performance levels among readily biodegradable and petroleum-based lubricants. Operators have many options from lower performance lubricants to high end, high performing “fully synthetic” products. While care must be taken in choosing the appropriate product for the specific application, Environmentally Acceptable Lubricants (EALs) also offer the full range of performance. It is important to know that some EALs provide even higher performance results than some petroleum-based lubricants.
EALS are defined by the EPA as having three characteristics:
ISO Classification for Hydraulic Environmental Lubricants includes four types of EALs:
Choosing the most suitable EAL depends on the end-user application.
THE NEED FOR OIL CONDITION MONITORING
Even the smallest hydraulic system failure can be very costly in terms of lost productivity, change-out times, and repairs. This is compounded in large-scale operations, such as oil rigs or dredging sites. When a hydraulic system failure occurs, it is commonly blamed on the oil or hydraulic fluid being used, and rightly so, since it is estimated that 90 percent of the time a fluid-related pump failure is due to contamination. It is important to examine HOW the contamination occurred, what might have been done to prevent it, and to use this information to mitigate future issues.
According to OEMs and tribologists, the primary cause of hydraulic system failure is water contamination. Through a series of chemical reactions, the presence of water in the system builds a corrosive environment, which shortens the life of the pump or other equipment. While it is impossible to prevent water from getting into your system, there is a series of procedures and protocols that can be implemented to measure the amount of water in the system and work to remove it before a failure occurs.
Sources of Water Contamination
It is virtually impossible to prevent water from entering a hydraulic system. Water can seep in through external sources (through cylinders or leaky seals, leaking into external reservoirs and even through rain or routine washdowns) or come from internal sources, including condensation and heat exchangers. For example, a system run in hot, humid environment takes in air containing water vapor, which condenses as it cools and remains in the hydraulic system.
This water can be present as dissolved, emulsified, or free water. The point at which the fluid cannot hold any more dissolved water is called saturation. Hydraulic fluid saturation points vary based on the fluid base oil and the additives used, as well as operating conditions, including pressure and temperature.
Problems Associated with Water Contamination
One of the signs of oversaturated fluid is cloudiness, although in a closed system, the level of water can be difficult to detect until there are problems.
Long before a failure, problems begin to occur when the saturation point is reached including surface corrosion, oxidation, reduced viscosity, lubricity, compressibility, and load-carrying capability, bearing system damage, hydrolysis, crystallization, higher operating temperatures, cavitation, foaming, premature additive depletion or sludge formation.
The Impact of Fluid Choice on Water Contamination
The type of oil used can have a major impact on water contamination and removing water from a system. Unlike traditional oils, which do not mix with water, some EALs, including certain hydraulic environmental synthetic esters (HEESs) and polyalkylene glycol synthetics (HEPGs) are emulsifying, which means they are intended to absorb water contamination. Hydraulic Environmental Polyalphaolefin and related hydrocarbon products (HEPRs) are demulsifying, which means that they separate water out from the fluid, rather than absorbing it.
Many producers of HEESs and HEPGs claim that, given their fluids’ ability to emulsify water, there is no need to check or remove water from the system. Most OEMs disagree, recommending draining and refilling any fluid with water content above 5 percent. The industry appears to be moving toward wider use of demulsifying lubricants, which allow water to be easily removed through normal separating methods.
Best Practices for Preventing System Failures Related to Water Contamination
There are many steps that can be taken to prevent failures.
There is a great deal of information and resources to assist in minimizing the risk of large equipment failures and maximizing uptime. OEMs have established product certifications and guidelines, and many fluid manufacturers offer insight into selection and monitoring. RSC Bio Solutions offers oil analysis programs to assist in understanding the state of your fluids, their impact on performance, and what you can do to extend fluid and equipment lifecycles. This analysis is performed by capturing oil samples during routine predictive maintenance to provide meaningful and accurate information on lubricant and machine condition. By tracking oil analysis sample results over the life of the equipment, trends can be established which can be used to help extend equipment life and eliminate costly repairs.
For more information visit the RSC BioSolutions website.