Machinery Lubrication

Machinery Lubrication May June 2013

Machinery Lubrication magazine published by Noria Corporation

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Page 49 of 59

Oil Filters LESSONS IN LUBRICATION BENNETT FITCH NORIA CORPORATION ANATOMY of an OIL FILTER This is the second part of a series of "anatomy" lessons within Machinery Lubrication. In this issue, the oil filter will be examined to uncover its functional and performance characteristics. Several other related topics will also be discussed, including best practices for oil filter usage, possible filter failure modes, factors for proper filter selection and how to maintain an installed filter. By definition, an oil filter's main role is to cleanse oil from destructive contaminants within a machine such as an engine, transmission, hydraulic system and other oil-dependent systems. In the case of automotive oil filters, canister-type filters are the most common. This filter configuration was most likely responsible for the advanced performance of oil filtration technology. In 1922, Ernest Sweetland invented the first oil filter device for automobiles. It was named the "Purolator," which was short for "pure oil later." The spin-on filters common in today's automotive industry were introduced in the 1950s and were virtually a standard by the early 1970s. Aside from the automotive industry, oil filtration is an integral part of equipment within a wide variety of industries, including aerospace, power generation, oil refining, manufacturing, mining, etc. Although most current oil filter designs come in canister or cartridge types, several variations in size, filter media, dirt-holding capacities and flow arrangements are available. For this reason, it is important that filters and filtration systems are selected to meet the needs of the application and with cost, performance, ease of use and environmental conditions in mind. through the housing. One technique used to control contamination in filters is through surface-type media. This is the type of filter used in automobiles. In depth-type filters, the filter media are designed to hold much higher levels of contamination and provide a more circuitous path for lubricant contaminants to become trapped. Other possible contamination control methods include magnetic and centrifugal filtration. Magnetic filtration utilizes rare-earth magnets or electromagnets to attract and collect ferrous particles as the oil passes through a magnetic flux region. Centrifugal filtration works by integrating a rapidly rotating cylinder to produce a centrifugal force for contamination separation from the oil. Oil filters can also be categorized by the oil flow design. As its name implies, a fullflow filter will draw all of the oil through the filter media. On the other hand, a bypass filter only requires a fraction of the oil flow for sufficient flow rates within the system. The application's oil flow and contamination control requirements will determine which design is the best option. Another alternative is the duplex filter system, which contains two side-by-side filters in parallel to allow one of the filters to be replaced during uninterrupted operation. With typical canister-type filters, it is standard for oil to flow from the outside in. This means that the oil travels through the cylindrical filter media from the outward-facing surface into the inner core. However, in some cases the flow direction is reversed, with the oil coming into the filter through the core and pushed outward through a unique pleat design. This is intended to improve flow handling and distribution as well as reduce filter element size. Oil Filter Types Filtration Mechanisms and Filter Media Oil filters can be characterized by the method in which the contaminants are filtered or the method in which the oil flows A filter's primary function is to remove and retain contaminants as oil flows through the porous component called the A filter not only is a trap for the machine's undesirables but also a concentration of clues as to what's occurring within the machine. 48 | May - June 2013 |

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