Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1412702
www.machinerylubrication.com | September - October 2021 | 7 ML ML While there are commodity (economy grade) filters of all types to choose from, as with many products, the greater value and quality often come from selecting the premium option at the high end of the price range. Yet, most premium high-performance filters can look very similar to cheaper, lower cost filters at first glance. Published data on filter perfor- mance by their suppliers is often embellished or out-of-date. After all, a filter supplier would never publish anything other than stellar perfor- mance data, and this data is usually the product of their own laboratory. My background in filter testing runs deep. Before Noria, I was the CEO of Diagnetics, Inc., the world's largest manufacturer of filter test stands. ese test stands evaluated filter performance to SAE and ISO standards. We also tested thousands of filters on our equipment. During that time, we became very aware of a common discrepancy between measured filter performance and the perceived quality of those same filters among the user community. Getting the Biggest Bang for Your Filter Buck Just like lubricant performance testing, in many cases, it is wise to get filters tested by an independent laboratory. For instance, if you have three filter brands you are considering, it would be advisable to get an objective, unbiased confirmation of the following questions: 1. Which filter gets the oil the cleanest (capture efficiency across the life of the filter)? 2. Which filter lasts the longest (dirt-holding capacity)? 3. Which filter has the lowest flow resistance (pressure-flow perfor- mance)? 4. Which filter is manufactured to the highest quality and fabrica- tion integrity (free of random defects)? Of course, you don't need independent testing to answer the final question: which filter is the cheapest? Fortunately, there are excellent standards available for answering questions 1-4. Sadly, testing filters to these standards has not been widely available to the user community. ese standards are: • ISO 2942: filter fabrication integrity (quality) • ISO 16889 and ISO 4548/12 (performance): particle capture effi- ciency, dirt-holding capacity, flow resistance • ISO 23369:2021 (performance): similar to ISO 16889 but for filters exposed to cyclic flow and other real-world conditions ere are numerous other test standards available, but these offer the greatest opportunity to optimize filter selection from the stand- point of value and performance. Together, these standards work towards achieving consistent lubricant cleanliness (within the target cleanliness) at the lowest possible cost. What Multipass Filter Testing Looks Like A multipass test stand is used to perform all the tests listed above except for fabrication integrity. is can be done for filters of numerous different sizes, configurations, and flow rates. A multipass test stand is a highly engineered machine with many circulating loops, a contam- inant injection system, two on-line optical particle counters and a 100:1 continuous dilution system (to ensure particle count accuracy). See Figure 1 for a visual idea of the engineering and science behind standardized filter testing. e forward-facing "bench side" of the test stand has three circular funnel-shaped reservoirs, as shown in Figure 2. e larger reservoir (far right) is the injection system reservoir that supplies a precisely metered Figure 1. Interior multipass system circuits and components. The dilution system and particle counters are mounted on the left interior panel. Figure 2. Above the sink on the left is where the filter being tested is mounted. The circular middle sinks are filter test system reser- voirs. The larger injection system reservoir is on the far right. Figure 3. Funnel-shaped sinks achieve turbulent flow, enabling controlled homogenous distribution of particles across a range of sizes during the test sequence.