Do you recall the first time you scanned an oil analysis report for information and were perplexed by the various names and units of measurement? Have you ever sat through a training seminar and wondered where and how these methods and units of measurement were named and developed?

Historically, many units/methods of measurement, analysis for tribology or any other scientific discipline were named after those who invented or discovered them, for example:

  • The temperature scale known as Fahrenheit is named after the German physicist Gabriel Fahrenheit, who proposed the measurement in 1724.

  • The volt is the SI derived unit of electric potential difference or electromotive force and is named in honor of the Italian physicist Alessandro Volta, who invented the first chemical battery.

  • Halley's Comet, seen every 75 to 76 years, was last seen in 1986 and will not be seen from earth again until mid 2061. This comet was named after Edmond Halley, who in his "Synopsis Astronomia Cometicae", stated his belief that the comet sightings of 1456, 1531, 1607 and 1682 related to the same comet, which he predicted would return in 1758. When it did, it became known as Halley's Comet.

So, who are the names seen in oil analysis today?

Oil analysis practitioners tend to hold viscosity in the highest regard. Many will say that viscosity is the single most important property of a lubricant. One of two units of measurement for viscosity are generally seen when oil analysis reports or product information sheets are viewed.

Jean Louis Marie Poiseuille (April 22, 1799 - December 26, 1869) was a French physician and physiologist who had an interest in the physics of blood circulation. From 1840 through 1846, he formulated and published Poiseuille's law, which focuses on the voluminal laminar stationary flow of an incompressible uniform viscous liquid through a cylindrical tube with constant circular cross-section. The poise or centi-poise can be applied to blood flow in capillaries and veins, to air flow in lungs, for the flow through a drinking straw or through a viscometer.

Sir George Gabriel Stokes (August 13, 1819 - February 1, 1903) was an Irish mathematician and physicist who made important contributions to fluid dynamics, optics and mathematical physics at the University of Cambridge. Stokes derived an expression for the frictional force exerted on spherical objects with small Reynolds numbers. His work on fluid motion and viscosity led to calculating the terminal velocity for a sphere falling in a viscous medium. This became known as Stokes' law. Later, the CGS unit (replaced by the MKS system, which was finally replaced by the SI system) of viscosity was named for Stokes in recognition of his work.

Moisture Detection
Moisture detection and quantification is typically performed in used oil analysis labs through titration. In 1935, German chemist Joseph Karl Anton Fischer (March 24, 1901 - April 16, 1958) began investigating methods for determining the moisture content in sulfur dioxide. By mixing a reagent containing pyridine, sulfur dioxide and iodine without the excess of water, Fischer was able to validate the reagent by adding known amounts of water. Satisfied with the results from this original reagent, Fischer never attempted to modify the formulation.

This method of titration was unpopular with laboratory technicians due to the difficulty in determining the end-point and therefore with reproducing consistent results.

The reagent also contained pyridine, which is a chemical compound containing carbon, hydrogen and nitrogen. Besides being toxic, volatile and a carcinogen, pyridine has an extremely sour odor.

Eugen Scholz began to develop other reagents for Karl Fischer titration that were less volatile and lacked the same foul odor. In 1982, Scholz developed imidozol which was a faster and more reliable reagent. Over the next 20 years, several generations of reagents have been developed using chloroform, triflouroethanol, carbontetrachloride, halogenated hydrocarbons and ammonium salts. Though the reagents may have changed over time, the process remains the same.

Vernon C. Westcott (1919 - September 26, 2003) invented the first ferrograph for used oil analysis. Originally developed for use in the military, ferrography is now a fundamental tool of oil analysis and reliability maintenance.

Westcott is considered the primary researcher and developer of ferrographic technology, not only in the field of machinery wear analysis but also in bio-ferrography as it relates to the capture and identification of cancer cells. A 1960s Navy program that focused on predicting roller bearing failures prompted Westcott to realize that the wear particles carried in the oil stream could reveal the condition of the bearing. His magnetic separation device separated the particles from the oil and produced a layer of wear particles that were analyzed when viewed through a special microscope, which provided a window into the bearing condition.

Jean Baptiste Joseph Fourier (March 21, 1768 - May 16, 1830) was a French mathematician and physicist who is best known for initiating the investigation of Fourier series and their application to problems of heat flow. The Fourier transform is also named in his honor.

With Fourier transform infrared spectroscopy (FTIR), the intensity of the infrared beam is measured before and after it interacts with the sample-specific spectral regions.

Oil Sampling
Born in Belfast, Ireland, Osborne Reynolds (August 23, 1842 - February 21, 1912) was a British fluid dynamics engineer who studied conditions in which the flow of fluid in pipes transitioned from laminar to turbulent. The result of Reynolds studies was a dimensionless number (Reynolds Number) representing the ratio of inertial forces to viscous forces. Flow typically changes from laminar to turbulent between Reynolds numbers 2,000 and 4,000. As always, it is best to take oil samples in a turbulent zone.

It is evident from these examples that many of the methods, units and procedures currently used in oil analysis have their roots in physics and chemistry and are related to many other areas of science.


1. Teresa Hansen, Noria Corporation. "A Tribute to Vernon C. Westcott, Inventor of the Ferrograph." Practicing Oil Analysis magazine, March 2004.

2. "Latest Developments of Karl Fischer Reagents - More Convenience and Less Toxicity." Analytix - Advances in Analytical Chemistry, March 2000.

3. Suzy Jamieson, International Council for Machinery Lubrication. "Recognizing Excellence in Machinery Lubrication - ICML Announces the John R. Battle Award." Machinery Lubrication magazine, November 2004.