YSI - a Xylem brand

YSI - a Xylem brand

YSI develops and manufactures sensors, instruments, software and data collection platforms for environmental and coastal water quality monitoring and testing. YSI also offers life sciences products including biochemical analyzers for bioprocess monitoring, food and beverage processing and sports physiology. YSI and SonTek/YSI environmental products and integrated systems are used throughout the world to measure, monitor, and improve the quality, quantity, and flow of Earth`s water supply. YSI works with water resources professionals in the coastal and estuaries, drinking water, ground water, surface water, wastewater, and aquaculture industries. Our sensor technology and rugged systems continue to provide leading-edge solutions for our water-related customers around the world.

Company details

1700/1725 Brannum Lane , Yellow Springs , OH 45387 USA
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Business Type:
Industry Type:
Water Monitoring and Testing
Market Focus:
Globally (various continents)
$10,000,000 US - $100,000,000 US

YSI is part of Xylem Analytics and a leading provider of water measurement solutions.

Xylem Analytics’ global brands have been leaders in the water and laboratory instrumentation market for decades, and are relied upon every day across more than 150 countries. Working in true partnership with our clients, we listen, learn and adapt to individual needs, offering deep application expertise built upon our long history of innovation in instruments and services. Our solutions for analysis, measurement and monitoring help enable many of today’s environmental monitoring, modern laboratories and industrial processes, and provide our customers the trusted and high performing solutions they need to succeed.

Xylem Analytics is part of Xylem Inc., a global company focused on solving the world’s most challenging and fundamental water issues. As accurate analysis is crucial to the water industry, Xylem Analytics taps its diverse product brands for leadership in that field and beyond, providing the best laboratory and field monitoring instrumentation across a wide variety of industries.

We work with industry and government professionals to provide monitoring and sampling solutions for process improvement and to protect our planet's natural resources.

YSI's environmental products provide high quality, high resolution data to better understand and manage our water resources. They are used for wastewater process control, climate change and drought studies, flood monitoring and warning, stormwater runoff monitoring, groundwater quantification and contamination, aquaculture production and source water safety. In addition to standard products, YSI's custom integrated systems help customers obtain critical data in most any application. Tell us what you need and let us design and deploy a total system, even if you simply just want the data.

Our environmental products provide infrequent maintenance cycles, user interchangeable sensors, and field-rugged enclosures all backed up by a passionate and knowledgeable technical support team.

YSI Life Science and laboratory products are considered the Gold Standard for QC applications. They are used for process control, research and industrial applications by food and beverage, environmental, biofuels, biotech and pharmaceutical customers.

When purchasing YSI, you can expect proven products and technologies that provide true value and low TCO (total cost of ownership). Whatever your instrumentation need, YSI is ready to provide a reliable solution. We know you are passionate about your work...we are equally passionate and enthusiastic about what we can offer to help you succeed.


In the beginning there were a few engineers and a lot of ideas.

The legacy of our global company reaches back to 1948 and a three-man partnership that was forged at Antioch College in Yellow Springs, Ohio, USA. This village, between Dayton and Columbus, still serves as the headquarters for what started as the 'Yellow Springs Instrument Company' — now known as YSI Inc.

We invite you to browse our brief history and explore our timeline.

A Brief History of YSI

Back in the late forties, two engineers, Hardy Trolander and John Benedict were joined by chemist David Jones and started looking for problems to solve through the application of good science. Shortly after the three men incorporated the company in 1948 and Hardy Trolander was appointed the first President, they were joined by David Case, another Antioch alumnus.

The four men worked with researchers at Fels Research Institute. Additionally, they bid on a job at the Wright-Patterson Air Force Base (formerly Wright Field) with the help of Fred Hooven, who became the fifth stockholder. Hooven had gained a reputation for his significant contributions to the Army Air Corps at Wright Field, among them being principal inventor of the automatic radio compass still in use today.

The Air Force accepted the men's concept for a 16k random access memory (RAM) with on-board crystal clock in response to its need for a programmable timing device with precision and resolution well beyond anything available at the time. This successful prototype led to Air Force contracts that produced cash flow to support development and commercialization of further ideas.

First instruments released and sales grow

After a few years as a struggling start-up, YSI's first commercial instrument was designed -- the Model 3A Dielectric Constant meter. Then followed interchangeable thermistor temperature probes, a notable industry first, and associated temperature instrumentation.

By 1960, YSI had several dozen employees and numerous instruments that had gained wide acceptance among scientists and researchers. A European distribution network was established early in this decade. The engineers continued to work hard to develop more innovative products.

Innovative sensor technology

The history of YSI would be incomplete without mention of Dr. Leland Clark, to whom not only YSI, but the world, owes a debt of gratitude. Dr. Clark was a researcher at Fels with whom Hardy Trolander and the others worked closely. He is best known for having developed the aptly-named Clark oxygen electrode that allows dissolved oxygen to be measured in liquids. Applications not only include environmental ones, but biomedical and industrial as well.

For example, his invention enabled physicians to perform open-heart surgery because, for the first time, immediate blood oxygen measurements could be taken real-time in the operating room rather than having a sample drawn which then had to be taken to a lab for analysis. Dr. Clark also developed the technology behind the glucose biosensor, used daily by millions of people with diabetes and other conditions.

In 1970, Dr. Clark demonstrated the enzyme-activated polarographic measurement of glucose in water and pointed out that glucose could be measured in whole blood with the presence of the glucose oxidase enzyme. Within a couple of years, YSI was able to market its pioneering Model 23 Glucose Analyzer with a polarographic electrode.

At this point in time, YSI was building a range of instruments based on precision sensor technology for temperature and biomedical applications.

Hardy Trolander believed strongly in the social benefits of a business enterprise -- one that gave its employees meaningful work; one that contributed to the economic health of communities and intellectual stimulation of industries. This legacy was continued upon Hardy's retirement in 1983, with the appointment of Malte vonMatthiessen as YSI's second President/CEO. Malte focused on expanding our niche markets, initiated quality improvement programs, and developed alliances with domestic and global partners. During this time, sales and distribution were set up in the Eastern hemisphere.

After several years with Malte at the helm, YSI began to sharpen its focus on product development and replaced the traditional hierarchical managerial structure with cross-functional and self-directed teams.

Innovation continues with upgraded R&D

Moving into the 1990s, the company adhered to a well-defined plan of providing quality products to specific global niche markets (environmental monitoring and testing, precision temperature measurement, and biotechnology) while continuing to reduce costs. YSI recognized its core competency in sensor technology and committed three million dollars for a new facility to house stepped-up sensor measurement technology teams.

Additionally, new product development and business processes incorporated environmentally responsible practices such as recycling, reduced-footprint packaging, and energy conservation.

During this decade, YSI introduced what became our most significant product line to date: the 6-Series environmental monitoring sondes. These instruments brought together YSI’s proven dissolved oxygen sensor with additional sensors into a family of products specific to monitoring water quality. Customers were able to leap out of the lab and into the field, where data was obtained more immediately and accurately.

Rick Omlor became YSI's third President/CEO in 2002. In 2005, Rick and his leadership team made the strategic decision to focus the business in a select few areas rather than following the 60-year history of ever broadened markets and sensor development. This strategy, focused mainly on the water quality and water velocity applications in the natural resource market, served the customer, company and shareholder very well.

In September 2011, in YSI’s 63rd year, ITT Corporation purchased YSI and, later that year ITT spun off its water-related businesses into a new publicly traded company, Xylem (XYL).

YSI, a Xylem brand, continues its legacy now with the backing of a 3 billion dollar company. It is part of Xylem Analytics, one of four divisions within Xylem where there are opportunities for expansion globally, sharing innovative technology across Xylem's brands but more importantly providing customers a more comprehensive solution to better meet their needs.

Xylem’s products enable its customers to sustainably transport, treat, test and efficiently use water in public utility, residential, commercial, agricultural and industrial settings, while Xylem Analytics is focused on field, portable, online and laboratory analytical instrumentation for applications in surface water, groundwater, coastal, aquaculture, wastewater and life science.

YSI will continue its legacy of invention and innovation as we move forward; and not just in the area of technology. We will continue to seek new creative solutions for remaining close to those who use our products and services, ways in which we operate our business, and methods for seeking and retaining talent.


YSI is a supplier of technology that is derived through environmentally responsible business practices.

As a responsible business, we are committed to continual improvement in environmental management and prevention of pollution in all business activities.

To that end we will:

  • Establish objectives and targets that consider environmental aspects as an integral part of our business decision making process.
  • Comply with all applicable laws, regulations, permits, company policies, and other requirements to which we subscribe.
  • Develop employee knowledge and understanding of environmental issues related to job functions.
  • Promote conservation of resources by reusing, recycling, and adopting processes that conserve the use of raw materials, energy, and water.
  • Strive to reduce the generation of waste from existing and future operations.
  • Communicate this environmental policy to all employees and make it available to the public.
  • Communicate with our customers and suppliers about ecological sustainability issues.
  • Consider principles of ecological sustainability in the design of our new products.

Implementing this policy is a primary management directive and the responsibility of all employees.


We maintain a quality management system to provide you, our customer, with quality, innovative products and services on time.

YSI is registered to or complies with several certifications and directives, including ISO 9001, ISO 14001, ISO 13485, Healthcare Canada, European WEEE, MCERTS, and EN46001.  New products are designed in accordance with the European RoHS directive.