Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/957021
16 | March - April 2018 | www . machinerylubrication.com How to Verify Oil Filtration Efficiency OIL ANALYSIS Steffen Nyman | C.C. Jensen Most maintenance profes- sionals know that clean oil can result in significant cost savings and that oil analysis can be used to reveal the state of lubricants and machines. However, as online particle counters and other sensors become increasingly popular, it is important to be aware that one number does not tell the whole truth about a system's conditions. It takes experience and a variety of tools to translate the vast amount of information that an oil sample carries. Understanding this language by using appropriate tools and efficient oil filters will help you reduce operation and maintenance costs associated with downtime, component wear and oil replacement. For example, consider an online particle counter installed to remotely monitor particles in hydraulic oil. It may show an ISO code of 16/14/11, which would lead you to believe that everything is perfect in the hydraulic system, but is it? Unfortunately, the particle counter cannot detect submicron or very large particles (greater than 200 microns), an installation fault in the counter, if the oil viscosity is off, or if additives have depleted. It also is unable to distinguish the oil color or smell, oxidation, acidity, varnish, water separation efficiencies (demul- sibility), or problems with air release or foam. erefore, you still need to perform traditional oil analysis and onsite tests. Old-school Methods to Verify Filter Efficiencies A sample can provide a lot of information about an oil's properties and system condition, even prior to shipping it to the laboratory. e following onsite methods can help you translate this information into corrective actions and verify the filter efficiencies of your oil system. Visual Inspection Examine the oil color. Is it comparable to new oil? Oxidation changes the oil color from amber to dark brown. Black usually indicates soot from combustion byproducts or entrained air causing micro- dieseling. Check for air leaks at the suction side of the system pump. Do you see any large wear particles as black or shiny sediment? ese would be greater than 100 microns. Use the crackle test (oil drop on a hot plate) to reveal the water level above 1,000 parts per million. Look for cloudiness, emulsions or free water. Does water ingress into the oil system? Check the oil's demulsibility by mixing the oil with water (50/50) and time the separation. More than 5 percent emulsions or more than 20 minutes to separate means the water sepa- ration by coalescence or centrifugal forces is severely impaired. Engine oils, esters, polyalkylene glycols and most environmentally accept- able lubricants can keep water in suspension so there is no free water. Shake the Sample Shaking an oil sample will indicate the foam and air-release properties. Observe how fast the "Filters are not created equal and cannot be tested using the same standards." " Oil with and without varnish