Level and Pressure Measurement

About Keller America

Introduction:

The name Keller has earned its place in the History of Pressure Measurement, as it is closely connected with the development of the piezoresistive technology.

In the 60's, company founder H. W. Keller developed the first integrated silicon pressure measuring cell at the Honeywell Research Center in Minneapolis. He also patented the integrated production method of this silicon cell in the United States. Products of National Semiconductor, Foxboro, and Honeywell have been directly or indirectly developed on the basis of this work.

At the beginning of the 1970's, Mr. Keller developed the first piezoresistive pressure transducer with a steel housing. Shortly thereafter, in 1975, H.W. Keller founded his own company, Keller AG für Druckmesstechnik. From humble beginnings, Keller AG has grown to a worldwide leader in pressure measurement solutions. From the advent of the Series 10 OEM pressure transducer, to the complete lineup of specialty pressure transmitters, Keller AG remains at the leading edge of development and innovation. With the advent of inexpensive, miniaturized microprocessors, Keller continues to advance the state-of-the-art with Total Error Band performance not possible just a few short years ago. Annual sensor production, combining OEMs with our own transmitter products, now exceeds 1 million pieces.

At Keller, we seek to remember the lesson of parable, " The Malady of the Five Monkeys." Success means choosing to change for the better; to evolve, adapt, and innovate. It is this philosphy that makes providing our customers with superior value a way of life at Keller. Contact us today, Toll Free: 877-253-5537 or send us a message.

History of Pressure Measurement

Mechanical Measurement Technologiess

1843

Lucien Vidie, French scientist, invented and built the aneroid barometer, which uses a spring balance instead of a liquid to measure atmospheric pressure. The spring extension under pressure is mechanically amplified on an indicator system. Employing the indicator method of Vidie, Eugene Bourdon (founder of the Bourdon Sedeme Company) patented the Bourdon tube pressure gauge for higher pressures in 1849.

Electrical Measurement Technologies

1930

The first pressure transducers were transduction mechanisms where the movement of diaphragms, springs, or Bourdon tubes is part of an electrical quantity. Pressure diaphragms are a part of a capacitance, the indicator is the tap of a potentiometer.

1938

The bonded strain gauges were independently developed by E.E Simmons of the California Institute of Technology and A.C. Ruge of Massachusetts Institute of Technology. Simmons was faster applying for a patent.

1955

The first foil strain gauges came up with an integrated full resistor bridge, which, if bonded on a diaphragm, see opposite stress in the center and at the edge.

1965

The bonding connection of the gauges to the diaphragm was always the cause for hysteresis and instability. In the 1960’s Statham introduced the first thin-film transducers with good stability and hysteresis. Today, the technology is a major player on the market for high pressure

1973

William R. Poyle applied for a patent for capacitive transducers on glass or quartz basis, Bob Bell of Kavlico on ceramic basis a few years later in 1979. This technology filled the gap for lower pressure ranges for which thin-film was not suited. Today, it is the widest spread technology for non-benign media.

The Sensor Age

1967

Honeywell Research Center, Minneapolis, USA: Art R. Zias and John Egan applied for a patent for the edge-constrained silicon diaphragm. In 1969, Hans W. Keller applied for a patent for the batch-fabricated silicon sensor. The technology is profiting from the enormous progress of IC-technology. A modern sensor typically weighs 0.01 grams. If all non-crystalline diaphragms have inherent hysteresis, the precision limit of this item is not detectable by today’s means.

1987

As a result of continued innovation, Keller was awarded another patent, US 4,685,469, for another peizoresistive pressure measuring cell.

2000

The piezoresistive technology is the most universal one. It applies for pressure ranges from 100mbar to >1500 bar in the absolute, gauge, and differential pressure mode. The slow spread of the technology in high-volume applications for non-benign media resulted from the inability of US-companies to develop a decent housing. In 30 years, KELLER has perfected it at costs comparable to any other technology.

Markets Served
Influencing Virtually Every Worldwide Market

Whereas many pressure measurement technologies are best suited for specific markets, the universal nature of the technologies embedded in Keller products results in our influencing virtually every worldwide market for pressure measurement.

Keller Sensors in Oil & Gas Reservoirs, Migrating Marine Mammals, Medical Devices, Commercial Aircraft

Keller sensors can be found deep inside the earth in oil & gas reservoir monitoring tools. Miniature Keller pressure sensors travel the oceans aboard migrating marine mammals, providing depth information critical to conservation programs. Municipal wastewater plants benefit from Keller level transmitters, which set the standard for reliability and cost-effectiveness. As well, doctors depend on Keller sensors for accurate control of a variety of medical devices. High above the earth, our transmitters are hard at work providing accurate cabin pressurization information on commercial aircraft.

Tailored Solution

At Keller, we are committed to continuing development of existing technologies as well as pioneering innovations that enable us to break into new markets previously dominated by others. Full scale ranges from only 4 inches of water Full Scale up to 29,000 PSI are all within the Keller capability, as are operating temperatures from -55 to 200°C. No matter what your market, Keller can offer a tailored solution.

More Questions?

More FAQ'S to come soon! In the meantime please do not hesitate to contact us if you need further assistance!