Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1123345
52 | May - June 2019 | www . machinerylubrication.com BACK PAGE BASICS environment, friction, etc. For the oxygen element to separate, only a small amount of energy is required (approximately 495 kilojoules). is is equivalent to 120 calories, which is about the same amount as a half slice of birthday cake. Hydrocarbons are a bit worse and require less energy. Any increase in heat creates a volatile environment, adding to the potential of oxidation and varnish formation. Other Bad Environments Other environments may also aff ect the life of a lubricant. For instance, water can impede lubri- cant life. However, this generally is accomplished by degrading additives that attempt to deter oxidation. Water requires a lot of energy to break apart, so oxygen availability is limited. In addition, metals can react with mineral oils, causing sludge. Process f luids may be damaging as well. Process acids can lead to major destruction. Ultraviolet light is another source of energy that can result in oil degradation. Controlling Oxidation Preventing the lubricant from a life of oxidation requires mini- mizing the availability of air and controlling heat. It is important to remember that heat alone will not lead to oxidation. It can only expe- dite the reaction process between two unstable elements. Since heat reduction or control may be diffi cult to achieve, controlling air availability is a better option. Following are some actions to better control air and heat in your systems. Air Control In circu lat ing lubric at ion systems, ensure the fittings and connections are tight. Air can be sucked into the lubricant through loose connections. Once inside, there is plenty of agitation to allow the oxygen and hydrocarbons to react. Also, keep your bearing seals in good shape. Air can infi ltrate through defective seals, enabling the oxygen and hydrocarbons to react and form oxidation products. On reservoir systems, maintain a positive pressure. Using an inert gas such as nitrogen prevents air from entering the system. Finally, consider oil mist. Although oil mist is mostly air, the temperatures are low enough to prevent the oxygen atoms from separating. It also provides positive pressure to keep external contami- nants at a minimum. Heat Control Always use the correct viscosity grade. Low-viscosity lubricants allow metal-to-metal contact, which gener- ates friction and results in excess energy from the heat produced. A high viscosity can cause internal friction and lead to similar problems. Your lubricant and equipment manu- facturer can help you determine the right viscosity for your application. Equipment vibration should also be kept at a minimum. Excess vibration can occur for a multitude of reasons and cause increased metal-to-metal contact and heat. Additionally, try to restrict external heat where possible. Use fi n fans or covers to inhibit the heat absorbed from the environment. Consider adding coolers to reduce heat buildup in the lubricant. Avoid Bad Environments How do you keep a good oil from turning bad? Analyze your lubri- cant systems, looking for air-entry avenues. Remove these points of entry wherever possible. Find the sources of heat and engineer methods to reduce or control that energy. Lubricants can have long lives free of oxidation. Equipment opti- mized in this manner will provide high production rates and minimal downtime. Just stay away from those bad environments. ML About the Author Keith Spoonmore is an inde- pendent consultant in lubrication and reliability. He holds a Level III Machine Lubricant Analyst (ML A III) certif ication from the Inter- nationa l Council for Machiner y Lubrication (ICML). His career spans sales, technical and engineering expe- rience with several major lubricant manufacturers and industrial compa- nies. He currently provides training and technical assessments for Noria Corporation and other independent work. Contact Keith at kspoonmore. ncic@noria.com to learn how Noria can help keep your lubricants in optimum condition. 78% of lubrication professionals say oil degradation products such as oxidation and varnish have caused problems for their plant's machines, based on a recent survey at MachineryLubrication.com