- Bently Nevada
[http://www.gepower.com/prod_serv/products/oc/en/bently_nevada.htm Bently Nevada] is a name long associated with condition monitoring instrumentation and services, most notably sensors, systems, and diagnostic services for monitoring machinery vibration. The offerings are primarily intended for assessing the mechanical condition of rotating equipment found in machinery-intensive industries such as oil & gas production, hydrocarbon processing, electric power generation, pulp & paper, water and wastewater treatment, mining, and the like.
Bently Nevada was a privately held US corporation between 1961 and 2002, during which time it pioneered the eddy-current proximity probe, a sensor that revolutionized the measurement of vibration in high-speed turbomachinery by allowing the direct observation of the rotating shaft. The company also performed significant research in the field of
rotordynamics, furthering knowledge of machinery malfunctions such as shaft cracks and fluid-induced instabilities. Its research also helped refine the equations used to describe vibratory behavior in rotordynamic systems.
The company was acquired by [http://www.ge.com/energy GE Energy] in February, 2002, and continues to design, manufacture, and market these products and services using the Bently Nevada name.
Bently Nevada was founded by
Donald E. Bentlyand remained privately held by him until he sold the business in 2002.
In the mid-1950s, Bently was graduate student in electrical engineering, briefly employed by an aerospace company where his work centered around aircraft control systems. At the time, these control systems were primarily mechanical/hydraulic in nature and his employer was investigating the use of electronic sensors as a replacement for some of the mechanical apparatus used. It was during this time that Bently was exposed to
eddy-currentsensors. The technology intrigued Bently and the aerospace company, believing there was limited use for such sensors, gave him permission to use the eddy-current technology in his own endeavors. Shortly thereafter, he dropped out of school and left his aerospace employer to form Bently Scientific Company in 1956. The company was located in Berkeley, California, and operated out of Bently's garage.
Although the idea of an eddy-current sensor was not original to Bently, he was the first to transistorize the design and make it commercially practical. Initially, Bently sold his eddy-current sensing systems via mail order and manufactured them one at a time. In October, 1961, the company was relocated to the small town of Minden, Nevada, and became Bently Nevada Corporation. Its primary operations remain there to this day.
In the company's early years, its non-contacting displacement sensors were used primarily for laboratory rather than industrial measurements. Often thought of as a type of electronic
dial indicator, such sensors are typically used to measure very small distances between the tip of the sensor and a conductive surface, such as a metal disk. The displacements measured are extremely small, typically on the order of several thousandths of an inch.
In the early 1960s, industrial users of turbomachinery began to experiment with the use of these sensors for measuring vibration. Direct observation of the vibratory motion of a machine's shaft is desirable because most often, the shaft is the source of vibration in the machine. Previous to the introduction of the so-called "Bently probe," this shaft motion had to be indirectly inferred by measuring the vibration of the machine's casing. While machinery casing measurements can be valuable under certain conditions, machines that employ fluid bearings generally have damping and stiffness characteristics that do not adequately transmit shaft vibration to the machine's casing. Consequently, direct observation of the machine's shaft (rotor) was recognized as a more accurate method of assessing condition on such machines.
The eddy-current proximity probes pioneered by Bently addressed this need, and quickly became the preferred method of assessing vibration and overall mechanical condition on large turbomachinery employing fluid bearings. Such machines and bearing types account for the vast majority of compressors, turbines, pumps, electric motors, generators, and other rotating equipment exceeding 1,000 HP, and can be found in abundance in most industrial plants. Thus, the primary focus of the company shifted from laboratory measurements to industrial measurements on rotating machinery.
Initially, the company sold only the sensors. However, there was a large demand for monitoring instruments that could be permanently connected to the sensors installed on the machine, providing a continuous display of the vibration amplitudes and providing alarms whenever the vibration levels exceeded a user-configured warning level. Bently Nevada began manufacturing monitoring systems as a result, and as user confidence grew in the reliability of such systems, customers began wiring the vibration alarms from these systems into the machine's controls to automatically shut down the machine in event of high vibration. Thus, Bently Nevada's instrumentation became machinery protection systems, not just monitoring systems.
The company continued to expand, making diagnostic instruments such as spectrum analyzers, tunable filters, and other signal conditioning and recording apparatus, in addition to its sensors and monitors. As time went by, it also became apparent that customers were in need of expertise to help interpret their vibration measurements. In response to this, the company expanded its service organization in the 1980s beyond instrument installation and repair to include a team of machinery diagnostic engineers, skilled in collecting and interpreting vibration signals to help customers identify and correct machinery malfunctions. Consequently, the company became well known for both its instrumentation and its machinery diagnostic engineers.
By 2002, Bently Nevada Corporation had more than 10,000 active products in its catalog and more than 100 offices in 42 countries. In subsequent years under GE ownership, the business has grown considerably.
In 1981, Bently branched out from his instrumentation manufacturing activities and established a pure research organization called Bently Rotordynamics Research Corporation (BRDRC or "Birdrock"). Its objective was to conduct rotordynamic research, furthering the knowledge of rotating machinery behavior, modeling techniques, and malfunction diagnostic methodologies. Its mission was considered complementary to Bently Nevada, with BRDRC focused on understanding how machinery behaved, and Bently Nevada focused on understanding and building instrumentation to measure machinery behavior.
BRDRC made a number of important contributions to the field of rotordynamics such as a better understanding of fluid-induced instabilities, advanced models for understanding shaft crack behavior, insight into rubbing malfunctions between stationary and rotating parts, and enhancement of the rotordynamic equations with a new variable lambda (λ) which denoted "the fluid circumferential average velocity ratio".
BRDRC also introduced several new data presentation formats, such as so-called "full" spectrum plots and "acceptance region" trend plots. Its research findings were published extensively in relevant technical journals, and the research that had practical commercial applications found its way into the the Bently Nevada product line.
Rotodynamic and machinery diagnostic expertise remains a core part of the Bently Nevada product line through its machinery diagnostics services organization.
Acquisition by GE
In February 2002, the company was sold to GE Energy (formerly GE Power Systems) for an undisclosed amount. Today, the products and services historically offered under the Bently Nevada name remain intact and continue to be supported and enhanced.
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