Water, Water Everywhere, but NOT in Your Hydraulic System By Dr. Bernard C. Roell, Jr.

September 21, 2016

According to original equipment manufacturers and tribologists, the number one cause of hydraulic system failure is water contamination. The presence of water in the system builds a corrosive environment, which shortens the life of the pump or other equipment.

Whether through a series of chemical reactions or external egress, water will accumulate in any hydraulic system.  Since it is impossible to keep it out, and given the damage it invariably causes, it seems obvious that the best maintenance strategy is to remove the water as quickly as possible.  However, I am often shocked by how many of those with whom I speak believe just the opposite, choosing lubricants that emulsify and absorb water in the system, rather than removing it.

The type of oil or fluid used can have a major impact on water contamination and the ability to remove water from a system. While traditional oil-based lubricants can be used on land applications, the United States Environmental Protection Agency’s Vessel General Permit regulations require the use of environmentally acceptable lubricants (EALs) in marine environments. However, traditional oils and different classes of EALs react differently with water. Unlike traditional oils, which do not mix with water, some EALs, including certain Hydraulic Environmental synthetic esters (HEESs) and polyalkalene glycol synthetics (HEPGs) are emulsifying, which means they are intended to absorb water. Hydraulic Environmental Polyalphaolefin and related hydrocarbons (HEPRs), on the other hand are demulsifying, which means that they separate water out from the fluid, rather than absorbing it.

Many producers of HEESs and HEPGs have claimed that, given their fluids’ ability to emulsify water, there is no need to check for or remove water from the system. However, most OEMs disagree, recommending draining and refilling any fluid with water content above five percent.

As the Vice President of Research & Development of RSC Bio Solutions, I pride myself on our team’s innovative spirit, thought leadership on key issues, and our commitment to providing the insight and information customers need. We’ve created this primer (pg. 4-11) to educate hydraulic maintenance professionals and lubricant buyers on the dangers of water in their systems and the best strategies for addressing this critical issue.  It’s just one of the many ways we help you Keep Moving. Forward.

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