Technology protects hydraulic systems and reduces operating costs

This is due to the very small diameter of the micro-glass fibres allowing for more interstitial spaces in the same given area to trap and retain contamination. The development of PURE POWER elements draws on Bosch Rexroth’s application experience as a manufacturer of hydraulic systems, as well as comprehensive flow analysis, and research undertaken into materials.

The micro-glass main filter layer assists in achieving optimum retention rates. In order to meet the requirements of ISO 16889:2008 (the international standard for evaluating filter performance), any filter element must have a ß-value exceeding 200, depending on the filter particle size rating. The ß-values of the new PURE POWER filter material have exceeded 1000 in real world tests. This maximises system availability as hydraulic fluids are optimally cleaned. It also prevents damage to the system and further contamination by removing a very high proportion of the contaminants in the first pass through the filter.

This is also the first time that a manufacturer has fitted all elements in its range with an additional antistatic conductive woven filter medium as standard. This creates a charge exchange between oil and filter material and so reduces the risk of electrostatic charge and discharge in the filter.

End users of hydraulic systems increasingly use zinc- and ash-free oils which typically have reduced conductivity. If this is less than 300 picosiemens per metre, the danger of electrostatic discharge increases. Discharge processes are often visible in the form of lightning discharges or they can be identified by a sizzling noise. Each discharge can burn tiny amounts of oil and reduce the service life of the medium. Discharges can also burn holes in the filter layers. This reduces the retention rate and increases the danger of particles passing through the filter and causing damage in the system. The antistatic conductive woven filter medium helps negate the risk of these issues.

As well as high filtration efficiency, the new material also increases the dirt-holding capacity of the filter. Compared with previous generations of products, the new filter elements typically absorb up to 50% more particles, thus prolonging service life by the same value under the same operating conditions. This reduces the costs of filter elements, their disposal and associated labour, and equipment downtime. The effect is even more pronounced when used with Rexroth filter housings with patented Cycloclean cyclone technology, where a doubling in dirt-holding capacity has been measured according to the ISO16889 multi-pass test, while retention capability increases tenfold using the same test. This is a direct result of the cyclone design maximising filter capacity by effectively pre-filtering the fluid.

Chris Gray, Project Manager Filtration at Bosch Rexroth, explained: “Hydraulic fluid contamination remains the primary cause of system failures, so the need to optimise filtration performance is vital. Our new filters draw on state-of-the-art materials technology and our extensive industry experience to deliver long service life and optimum performance in a broad spectrum of industry applications.”