East Hills, NY (May 17, 2005) - - The increasing use of synthetic media filters to provide finer filtration and higher flow rates in industrial processes that use hydraulic and lubricating oils, ranging from power generation to pulp and paper production, has brought the problem of electrostatic charge to the forefront. There is increasing recognition that electrostatic charge can damage the filter element, its housing and the fluid resulting in increased wear to system components, downtime and costs and, as importantly, loss of reliability. In a presentation today at the 60th annual meeting of the Society of Tribologists and Lubrication Engineers (STLE), Leonard Bensch, Ph.D., Vice President, Pall Corporation (NYSE: PLL), reported the results of new research on why this phenomenon occurs and how it can be prevented.
Electrostatic charge occurs in fluid systems as a result of friction between the fluid and system components, including filters. Charges generated by the filter can collect on the filter element building up extremely high voltages in the order of tens of thousands of volts. It is a well-known problem in systems using hydrocarbon fluids, predominantly fuel and lubrication oils, but less is known about it with hydraulic fluids.
Many methods have been investigated to prevent charging and the damage that can occur if the electrostatic discharge continues unchecked. One preventative safety measure to reduce external discharge is the use of grounded filter housings and pipelines; however this method does not stop either fluid charge generation or internal damage to the filter or other system components caused by sparking. Another method, adding anti-static additive to the liquid, is restricted only to fuel applications. Other approaches are surface modification of the filter media or incorporating conducting materials into the construction of the filter element. These methods can eliminate direct damage to the filter cartridges but do not prevent charge generation. Additionally, the charge can be carried in the fluid downstream of the filter to reservoirs where it can also accumulate and cause sparking.
"Although it is important for engineers to understand why and how electrostatic charge occurs and recognize that it can be damaging, it is even more important to know that the problem can be prevented," says Dr. Bensch.
He presented the results of an experimental program to determine the effects that different filter materials have on hydrocarbon fluid charge generation. The study measured the charge generated on the material as well as the charge passed downstream. A variety of filtration materials were tested, both in flat sheet and pleated filter element configuration, using five commonly used oils to evaluate the differences in charge generation and material damage.
The experimental analysis found that the Ultipleat® SRT filter's novel material dissipates electrostatic charge, eliminating filter damage while also significantly lowering migration of charge into the downstream fluid compared to standard glass fiber filters. Its proprietary anti-static construction eliminates potential electrostatic charge problems in filtration of hydraulic and lubricating fluids by preventing or significantly reducing both charge generation and its accumulation.
According to the study results, engineers can be assured of all the advantages of finer filtration and higher flow rates without exacerbating the potential problem of electrostatic charge.
"Since its introduction to the marketplace, the Ultipleat SRT filter is rapidly becoming the filter of choice for a wide range of equipment and manufacturing processes," says Dr. Bensch. "Engineers will be able to realize all of its benefits including high performance, consistent contamination control, and cost efficiency in a compact footprint without sacrificing reliability and longevity of their fluid systems due to electrostatic charge."
About Pall Corporation Pall Corporation is the global leader in the rapidly growing field of filtration, separations and purification. Pall's business is organized around two broad markets: Life Sciences and Industrial. The Company provides leading-edge products to meet the demanding needs of customers in biotechnology, pharmaceuticals, transfusion medicine, semiconductors, water purification, aerospace and broad industrial markets. Total revenues for fiscal 2004 were $1.8 billion. The Company headquarters are in East Hills, New York with extensive operations throughout the world.
"Overcoming the Electrostatic Discharge in Hydraulic, Lubricating and Fuel Filtration Applications by Incorporating Novel Synthetic Filter Media " is being presented on Tuesday, May 17 at 9:00 a.m. at the STLE annual meeting at Bally's in Las Vegas, Nevada.
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Leonard Bensch, Ph.D. has worked in the field of filtration and contamination control for 37 years and has authored over 125 technical papers and articles on the subject. He is chairman of the USA Technical Advisory Group to ISO for contamination control and is also on the ISO filtration test methods working group. He is also active on the NFPA and SAE standards committees. He received his BS, MS and PhD. degrees in mechanical engineering from Oklahoma State University where he also co-led research projects in hydraulic filtration and contamination control for 12 years. Dr. Bensch was instrumental in the development of the most modern hydraulic filter test methods and contamination analysis techniques.