Posted to News on 23rd Aug 2009, 20:36
Long-life, high-reliability bearings for centrifugal pumps
The successful and efficient operation of many production and treatment processes is dependent upon the reliability of centrifugal pumps. Accounting for about 80 per cent of the UK market, these pumps are used for a variety of applications, ranging from the provision of cooling fluids during manufacturing processes to the removal of wastewater.
Because Centrifugal pumps are central to so many types of process, failures can result in catastrophic consequences that can be both hazardous and costly. Maximising bearing performance and reducing any potential pump failures is therefore critical.
NSK has worked with the pump industry to meet these operating demands and the result is the HPSTM (high-performance standard) range of angular-contact ball bearings. The basic dynamic load rating of these bearings has been improved by 20 per cent, increasing bearing L10 life by up to 90 per cent. This allows for longer maintenance intervals and can enable a reduction in bearing size for new pump designs.
The optimal design characteristics that provide longer life operation on the HPSTM series are also key to the higher speed operation of the bearings; permissible speed is increased by 15-20 per cent compared to conventional angular contact ball bearings. The major benefit of this increase for pump users is reduced operating temperatures, enabling the bearings to operate in a broader range of high-speed pumping applications.
Furthermore, the efficiency of the HPSTM design also means that the bearing's improved higher speed capability is delivered at the same time as bearing accuracy is maximised. This is evidenced by a running accuracy to ISO tolerance class P5 and a dimensional accuracy to ISO tolerance class P6. These tolerances enable tighter control of shaft run-out, aiding the performance of the mechanical seal and improving overall pump efficiency.
A choice of three cage materials enables the HPSTM series bearings to be configured easily to meet the operating requirements of most pumping applications. The cage materials include: glass fibre-reinforced polyamide 46, which provides high strength even at high temperatures; L-PPS resin, for applications where chemical and oil resistance is critical; and machined brass, which offers high reliability and compliance with API 610 standards.
The HPSTM range of angular contact ball bearings is available in the 7200 series and 7300 series, from 12mm bore to 80mm bore, and can be retrofitted during general maintenance to upgrade standard industrial bearings, or incorporated in new designs to provide superior performance.
Other HPSTM bearings
In addition to angular-contact bearings, NSK's HPSTM bearing series also includes innovative spherical roller bearings (SRBs). These offer innovative performance with a running life that is claimed to be twice that of conventional SRBs of the same size, and a maximum limiting running speed that has been improved by up to 20 per cent. The HPS series provides significant benefits across industry sectors such as extraction, steel, construction and transport, by reducing maintenance and energy costs, and enabling product downsizing.
