Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/325287
www.machinerylubrication.com | May - June 2014 | 35 options must be considered to achieve the system's target ISO cleanliness codes. The filter's physical location in the lube system will make a difference in some of the decisions such as media type and construction material. With full-flow filters or when filters are installed in the supply line, they offer direct protection to components downstream of the filtration system. Since these filters are in the path of the oil before it lubricates any components, they must be monitored for any signs of filter plugging or the filter going into a bypassed state. The term "bypass" is a reference to an internal valve that opens when pres- sure becomes too great. If the filter's bypass valve is opened, the oil flows around the filter and continues through the system unfiltered. When installing full-flow filters, ensure you have differential pres- sure gauges to monitor the health of the filters and to confirm oil is still flowing through the system. Return-line filters are common in most hydraulic systems. They are installed in the line after all lubricated components and before the main reservoir. While these filters don't offer direct component protection like supply-line filters, they are often oversized, which can lead to longer filter life. Typically, these filters are installed in tandem, so if one becomes plugged, the line can be switched over to allow the plugged filter to be changed without disrupting lubri- cant flow. Aside from being oversized, return-line filters usually have high beta ratios. The beta ratio refers to the filter's capture efficiency. The higher the beta ratio, the more efficient the filter is in capturing particles at the rated micron size. Kidney-loop systems offer the best option for reaching total system cleanliness targets. Since they don't require the system to be working in order for the filters to be active, they provide a more econom- ical method of removing dirt. With kidney-loop systems, it is also easy to add additional lubri- cant conditioning and monitoring accessories, such as heat exchangers, temperature gauges, online water meters, etc. These accessories can help ensure that the health and life of the oil are monitored and controlled as much as possible. Filter carts and other portable filtration devices can be used as a kidney-loop filtration system on most machines. These allow you to decontaminate the in-service lubricant as well as clean the oil as it is transferred from the drum into the system. An added benefit of portable systems is that they can be moved from one system to the next. Care should be taken to make certain that they are dedicated to a single lubricant to avoid any potential problems with cross-compatibility between different lubricant types. To maintain and improve system cleanli- ness, a balance must be established to remove particles as quickly as they are ingressed. For this to be achieved, the correct filtration system must be employed. In most cases, utilizing multiple filter locations offers the best way to hit the cleanliness targets that the machine requires to operate at optimum reliability. By reducing the number of particles in the oil, you can extend the life of the machine and make your facility more profitable. About the Author Wes Cash is a senior technical consultant with Noria Corporation. He is a mechanical engineer who holds a Machine Lubrication Techni- cian (MLT) Level II certification and a Machine Lubricant Analyst (ML A) Level III certification through the International Council for Machinery Lubrication (ICML). Contact Wes at wcash@noria.com. Off-line filters are a relatively modern alternative or addition to conven- tional full-flow filters. These filters sit off the main operating system as a side loop from the reservoir. A necessary supplemental component to the off-line filter is a pump and motor. Because it does not depend on the hydraulic system, it can run independently, even when the main system is off. The following are a few additional benefits of off-line filtration: • Constant flow optimizes dirt-holding capacity and capture efficiency for a given type of filter • Easy to service "on the run" (filter changes, repairs, etc.) • Heat exchanges can be built in the loop • Sample ports can be installed for sampling on the run • Lowest cost to remove a gram of dirt (expensive pressure-line and surge-resistant filters are required) • Can double for an oil transfer system for adding makeup oil Benefits of Offline Filtration SGS Herguth leads the industry in high quality innovative condition monitoring analysis for industrial users. 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