Some of you are personally acquainted with my father, Dr. Ernest C. Fitch. Others may know of him by reputation or perhaps through his publications. Later this year he turns 82. (Editor's Note: Dr. Ernest C. Fitch passed away in March 2011.)

His knowledge and vision have been an inspiration to me throughout my career. He is a great mentor and motivator. Today, he continues to make his mark in the fields of tribology and fluid power. However, in my mind, it was his seminal work in contamination control that most encouraged me to publish this interview. From my observations, the applied knowledge of contamination control in the past 25 years by hundreds of companies and government agencies has had a far-reaching and lasting impact on machine reliability, more so than any other maintenance initiative during the same period. A short biography of my father’s career is included in the sidebar.


E.C. Fitch with Son, Jim

Q. Let’s start at the beginning. Tell us about your introduction into the field of contamination control … when, where and how? Was it a mere accident or did a strategic vision bring you to this subject?

A. In the spring of 1958, I was awarded an Air Force contract to study fluid contamination in aircraft hydraulic systems for Tinker Air Base in Oklahoma City. I began the program by conducting a major literature research study in the field. My involvement in this work was interrupted by a sabbatical leave to complete my Ph.D. at the University of Oklahoma. Upon my return to Oklahoma State University (OSU), the Air Force awarded me a new contract that continued its research sponsorship for the next nine years. With this support, I gained factual knowledge of contamination control and hands-on, real world experience on many different systems at various Air Force bases. This proved to be an unusual opportunity to acquire an unbelievable background that has served me well throughout my lifetime of work in the field of fluid contamination control.

Another important event relates to a report I wrote in November 1962 entitled “A Basic Science Program in Filtration Mechanics”. The National Aeronautics and Space Administration (NASA) in Huntsville, Alabama received a copy of this bulletin and offered to sponsor a six-year research program on the subject. What a lucky break! This resulted in the establishment of the Basic Fluid Power Research (BFPR) Program, which lasted until I retired. NASA encouraged me to investigate various test procedures in contamination control that were relevant to the capture and retention of particulate matter in hydraulic systems. Between the NASA and Air Force research studies, a tremendous amount of spin-off subjects of special interest to my BFPR sponsors were discovered and published.


Books Authored by E.C. Fitch

As graduate advisor in mechanical engineering, in June 1966 I graduated my first doctoral student in contamination control, Roger H. Tucker, followed shortly by Robert Bose and Ross M. Stuntz, with many others in the pipeline. In the subsequent years, these students investigated subjects such as:

  • Contaminant generation by cavitation
  • Contaminant sloughing of components
  • Valve contamination sensitivity
  • Filtration mechanics – particle capture and retention
  • Analytical ferrography and wear debris analysis
  • Contamination tolerance of mechanical components
  • Mathematical models for contamination control
  • Contaminant effects on pump reliability and service life

In June of 1969, the U.S. Army initiated its contamination program with the BFPR, which ran for more than 10 years and culminated in the development of several hundred test procedures, many of which are in use today as NFPA, ANSI and ISO standards. At this point, I decided our laboratory needed an identifiable name to represent our work. In September 1969, the university approved the new name as the Fluid Power Research Center.


Dr. Fitch served as U.S. delegate to
ISO for more than ten years

Q. What or who inspired you most to continue your pursuits in the field of contamination control? Who were the early pioneers and mentors?

A. Beginning around 1970, as a result of our work for our BFPR sponsors and government contracts, I became associated with many distinguished engineers in the field of contamination control. These include Fred Cole of Bendix, John Farris, Erwin Kirnbauer and Leonard Bensch of Pall Corporation, Finley Steele of the Hillard Corporation, Gene Falendiz of J.I. Case, I.T. Hong of Bardyne, R.K. Tessmann of FES, Inc., Marvin Graham of John Deere and Zeke Lansky of Parker Hannifin Corporation. Each of these men helped me gain an in-depth knowledge of the intricacies associated with contamination control. Many of them accompanied me to ISO committee meetings where we achieved and were recognized with much success throughout the 1970s.

Q. Speaking of the International Organization for Standardization (ISO), in your view, what were your main accomplishments during your tenure as chairman of the ISO TC131 Contamination Control committee?

A. Beginning in December 1973, I served on many standards committees in the United Sates (NFPA, SAE, ASTM, ANSI) and then later internationally (ISO, BSI, NATO, Hydravlika, CETOP). We submitted many proposed test procedures originally developed at the Fluid Power Research Center (or at least those in which we had direct involvement). A few of the most recognizable to your readers include:

  • Fluid Sampling – ISO 4021
  • Bottle Cleanliness – ISO 3722
  • Particle Counter Calibration – ISO 4402
  • Multipass Filtration Performance (Beta Rating) – ISO 4572

Q. Is there a single standard or test procedure that rises above all others in terms of its significance to the field of contamination control?

A. Absolutely! It was without doubt the Multipass Filtration Performance (ISO 4572) test standard, also known as the Beta Rating. This proposed standard needed the support and consent of voting member delegates from many countries represented at ISO. The pressure was particularly intense because this was the procedure that the U.S. Army wanted passed so it could purchase filters of uniform performance capability around the world. We first had to obtain National Fluid Power Association (NFPA) approval, then the American National Standards Institute (ANSI), and then finally it went to ISO’s TC-131 committee. The process demanded me to make at least 10 trips to influential countries to garner their support. Finally in 1978, this major standard was approved.

I remember the day, back in 1969, when Ross Stuntz came into my office and proposed changing from filter efficiency to a Beta Ten concept. Talk about companies wanting to shut us down – it was unbelievable! The NFPA decided to conduct its contamination control committee meeting at the university, hoping to dampen our thoughts of making the change. Instead, it just encouraged us, and with the support of the Army, we marched on.

Industry finally realized that the outdated filter efficiency protocol (both nominal and absolute) had to go. There were just too many ways filter efficiency was tested and represented (no unified international test methodology). As a result, another test method name (instead of efficiency) was needed. Beta became the chosen term.

Q. Today there are more than 25 different optical particle counters marketed for use with lubricants and hydraulic fluids. What can you tell us about the history of optical particle counting? What were some of early challenges the FPRC faced in developing suitable methodology for using optical particle counters with oils?

A. Our first attempt at counting particles in hydraulic fluids without the aid of a microscope was using a Coulter counter. This type of particle counter employs an electrical sensing zone to monitor changes in conductivity caused by particles flowing through an orifice. We had to develop a suitable electrolyte to make the oil electrically conductive.

This handicap was significant enough that we purchased a new technology called HIAC optical particle counter from its creator, Leon Carver, who worked out of his “red barn” in Clairmont, California. Along with the sponsorship of the Air Force in 1962, this acquisition allowed us to be quite effective in automatic particle counting. In fact, this expertise was what enabled us to secure two large contracts from Wright Patterson Air Force Base for developing hydrocyclones for service on operational aircraft.

Our work using optical particle counters encouraged NASA to support us in developing a calibration method. We elected to go with Air Cleaner Fine Test Dust (ACFTD) as the standard particle size distribution. Although NASA and the Air Force accepted our calibration method, it was not adopted by HIAC and the rest of the industry. In fact, this was not achieved until the U.S. Army started sponsoring our contamination control work and our NASA particle counter calibration method was submitted as an Army procedure to NFPA, where it later became a NFPA, ANSI, and ISO standards. Of course, this original procedure was changed in 1999 with the involvement of NIST.

Q. Tell us about the history and beginnings of the ISO Solid Contamination Code (ISO 4406). Why were 5 and 15 microns selected for range numbers?

A. In reality, the ISO Code terminated industry’s quest, which started back in the late 1950s and early 1960s, for a method of specifying the particulate cleanliness levels of fluids. Many individuals and organizations tried and failed, including the FPRC and myself, to develop such a procedure.

Credit must be given to Peter J. Wilson who worked for the Vickers European group in Portsmouth, England. He was a member of AHEM, BSI and ISO contamination committees. When he told me about the idea over a beer, my first reaction was that it seemed too simple to be accurate. After some research, I realized that he had made an important contribution. I was honored to support this concept for Peter and it was finally approved by ISO in 1974. After returning home from the ISO meeting, I wrote a paper entitled “The New ISO Cleanliness Code – Let’s Use It.”

The Code is based on a step ratio of two for particle concentration above 5 and 15 micrometers per unit volume of fluid, respectively, to create a bimodal system using specific range numbers for describing the contamination level of a fluid. Peter Wilson selected 5 to reflect the silting condition of the fluid and 15 to reflect the prevalence of wear particles. Thus, the range numbers associated with the number of particles at 5 and 15 micrometers became the ISO standard. Today, ISO has established an ISO Code involving a trimodal system - using particle sizes 4, 6 and 14 micrometers instead of the original 5 and 15 size particles. Over time, as automatic particle counters become more accurate, the trimodal system may become increasingly important, but I question its value at the present time.

Q. Of the more than 20 books you have authored, your book Fluid Contamination Control (FCC) has been your all-time best seller. Now you have nearly completed the fourth edition of this widely-read reference, co-authored by me. Tell us, what is new and different in this edition?

A. The four editions of FCC have presented answers to many of the questions engineers and maintenance professionals have had with respect to contamination control. It would have been impossible to write such a book without the research conducted by the FPRC. As a result, the seminars I presented using these editions reached thousands of attendees around the world. In the fourth edition of FCC, nothing that I can back up with data has been left out. I think it will be well received, particularly considering the additional material that you are adding to the book from your work in contamination control with user organizations.

Q. What do you view as the single most monumental event in your career in contamination control, tribology and oil analysis?

A. It’s probably a toss-up between particle counter calibration and the Beta filter test method. However, I think that our Omega work, relating to rating hydraulic component contaminant sensitivity, is significant because practically no one else in the industry is working on this subject. Yet, what is really being accomplished from a design, materials and manufacturing standpoint to improve reliability and service life of new components and equipment? Someday, the importance of this subject is finally going to register and component manufacturers are going to be caught napping!

Short Biography of Ernest C. Fitch

Dr. E. C. Fitch began his engineering career as a journeyman machinist before entering the military in World War II. After receiving his Master of Science degree in mechanical engineering from Oklahoma State University, he set out to gain practical experience by taking jobs with Jersey Production Research, Boeing Aircraft, Deere and Company, Cincinnati Milacron and Cessna Fluid Power.

During his 35 years on the faculty of Oklahoma State University, he advised more than 100 doctoral and master degree students and countless undergraduate students. In order to provide a hands-on research opportunity for his students, he started a contract research center in 1956 that became the Fluid Power Research Center (FPRC). At least 160 industrial companies and governmental agencies sponsored research that provided financial support for his students.

For 18 years, Dr. Fitch headed teams of research engineers in developing hundreds of test procedures relating to tribology, contamination control and fluid power. Many of these procedures have since become national and international standards. He has served as member and chairman of half a dozen standards committees including SAE, ANSI, NFPA and ISO.

During his career, Dr. Fitch co-founded several companies providing services relating to hydraulics, tribology and contamination control. He has served on more than 250 consulting projects, nearly 200 court cases and has written more than 210 technical articles and 20 books. Dr. Fitch has been awarded 16 U.S. and 15 foreign patents and has five patents pending. From the 1960s through the 1980s, he has served as editor-in-chief of three international technical journals.

Dr. Fitch is currently Emeritus Professor of mechanical and aerospace engineering at OSU. He has received 15 major honors and awards from state, national and international professional organizations. Some of the most notable include:

  • Wonders of Engineering Award by Society of Professional Engineers

  • Distinguished Educational Leader by Fluid Power Society

  • Named SAE Fellow for his leadership in standards work

  • National Achievement Award by the National Fluid Power Association

  • Awarded Honorary Professorship, Huanghong University of Science and Technology, Wuhan, China

  • Named Distinguished Professor in mechanical engineering for 11 years by the OSU Board of Regents and Faculty, until his retirement

  • Hall of Fame recipient at Oklahoma State University Alumni Association

He currently devotes most of his time to the completion of four new books in fluid power, pneumatics, contamination control and maintenance and reliability.