Brian P. Dahmer is manager of application engineering at SKF USA Inc., based in Lansdale, Pennsylvania. He may be reached at 267-436-6517 or firstname.lastname@example.org. For more information, visit skfusa.com.
Alternative bearing options can enhance reliability and increase energy efficiency.
Turning to Contact Angles
Typically, 40-degree matching contact angles for pump bearing rolling elements have become the norm for paired single-row angular contact bearings in American Petroleum Institute (API) pumps. For conventional double-row bearings used in American National Standards Institute (ANSI) pumps, matching 30-degree contact angles are typical.
Particularly for the 40-degree paired single-row bearings, a change in the opposing contact angle can benefit many centrifugal pump applications by promoting smoother operation and longer service life in the way they support loads.
Pump bearing arrangements engineered with dissimilar opposing contact angles—a combination of 40-degree and 15-degree—can carry higher thrust loads with the 40-degree bearing without unloading the opposed 15-degree bearing. Greater axial loads can be applied, and the bearing’s operating temperature will decrease.
These 40/15-degree angular contact ball bearing arrangements are ideal for applications where the axial load is high in one direction and does not change direction during operation. The bearing sets can accept momentary reversals in axial load, including those that occur during pump startups and stops.
In centrifugal pumps with light thrust loads and predominantly radial loads—such as double-suction impeller pumps or pumps with closed impellers—bearing arrangements featuring only 15-degree contact angles offer yet another upgrade alternative.
Compared with conventional 40-degree matched bearing arrangements, the design of these 15-degree bearings promotes cooler running, substantially reduced vibration and extended service life in applications with high radial loads.
Generating Energy Efficiencies
Reducing energy consumption in a system remains a top priority in today’s marketplace, and certain bearings have been introduced to help users reach this goal. One of these bearing families includes two types commonly used in centrifugal pumps: deep-groove ball bearings and double-row angular contact ball bearings. Both types have been internally modified to decrease energy consumption by at least 30 percent compared with standard International Organization for Standardization (ISO) products while maintaining the service life and load-carrying capacity of conventional versions.
Relevant energy-saving technical improvements to deep-groove ball bearings for pumps include optimized internal geometry, newly designed polymer cages, and the use of lower-friction grease for sealed or shielded variants. For the double-row angular contact ball bearings, proprietary technical improvements that deliver energy savings include optimized internal geometry, steel shields on both sides and unique low-friction grease.
Both types of bearings, which are dimensionally interchangeable with conventional bearings, have been highly engineered to reduce friction and, in turn, decrease energy use.
As these innovations demonstrate, pump bearing design and engineering will continue to evolve as operators seek to improve the performance of existing pumps and take advantage of advanced technologies for minimizing problems and maximizing output.