Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1222953
6 | March - April 2020 | www . machinerylubrication.com AS I SEE IT to co-exist in the oil, a common consequence is entrained air. Emulsified water changes interfa- cial tension and impairs the ability of oil to rapidly release entrained air to the atmosphere. When air fails to detrain, a tertiary consequence is oil oxidation and adiabatic thermal failure, among others. Likewise, when dirt ingresses through tank headspace openings and enters the oil, this dirt abrades surfaces and leads to wear metals. is in turn accelerates the formation of oxide insolubles, leading to surface deposits and varnish. e list of secondary and tertiary consequences of dirt and water contamination is almost endless. Although not always practical, touching the inside ceiling of a reservoir to look for condensation water on your fingers can provide a quick indication of saturated moisture in your sump or reser- voir. Additionally, a highly visual sight glass, such as the one shown on the left, can quickly reveal emulsified water and evidence of corrosion caused by moisture. ML About the Author Jim Fitch has a wealth of "in the trenches" experience in lubri- cation, oil analysis, tribology and machinery failure investigations. Over the past two decades, he has presented hundreds of courses on these subjects. Jim has also published more than 200 technical articles, papers and publications. He serves as a U.S. delegate to the ISO tribology and oil analysis working group. Since 2002, he has been the director and a board member of the International Council for Machinery Lubrication. He is the CEO and a co-founder of Noria Corporation. Contact Jim at jfitch@noria.com. BEWARE OF WATER-INDUCED CORROSION FROM SEALED RESERVOIRS Water, regardless of its ingression source, must have quick and unrestricted means of exiting the reservoir as vapor. Some hydraulic systems have pressurized or piston-cylinder reservoirs. There are different reasons for this, but for the most part, they are found in mobile equipment applications. What happens too often is that high original or ingressed moisture is being locked into the circulating oil. Because the reservoir is pressur- ized, the moist vapor is unable to exhaust at operating temperatures. Instead, it is continu- ously re-condensed and entrained. A robust anti-rust package usually is able to protect headspace surfaces. However, this thin- film protection can be lost in the presence of zinc dialkyldithiophosphate (ZDDP) decompo- sition products from hydrolysis and continuous exposure to wet headspace fog. Inspection Tactic Inspection of hydraulic fluid for saturated water is essential. Any emulsified water observed in lines and tank sight glasses is cause for alarm. Look for evidence of corro- sion on oil-wet and headspace surfaces, filter element and housing hardware, and similar places. This sight glass makes the appearance of harmful levels of water easy to observe. The cloudiness of the oil indicates emulsified water, while the rust on the corrosion gauge punc- tuates the potential damage occurring to exposed internal machine surfaces.