A brief history of cleanrooms

By Sheila Galatowitsch

Cleanroom historians say the concept of contamination control originated as early as the mid-19th century in hospital operating rooms. Modern cleanrooms, however, were born out of the need for precision manufacturing in clean environments during World War II and the subsequent race to space.

During World War II, industrial manufacturers in the U.S. and U.K. developed the first cleanrooms to improve the quality and reliability of instrumentation used in guns, tanks and aircraft, according to W. Whyte in his 1991 book Cleanroom Design. “It was realized that the cleanliness of the production environment had to be improved or such items as bomb sights and precision bearings would malfunction,” Whyte wrote.

Although historians do not pinpoint a date, most agree that the high-efficiency particulate air (HEPA) filter was developed during World War II and became available for industrial use in the early 1950s. Laminar flow technology was formulated in 1961 by a team of Sandia Laboratories researchers led by Willis Whitfield.

One historian writing in the mid 1960s claimed that predecessors of modern-day cleanrooms go back to World War I. Philip Austin in his 1965 book, Design and Operation of Clean Rooms, described “controlled areas within factories or laboratories in which an attempt was made to eliminate the gross contamination associated with manufacturing areas. This contamination, consisting of heavy dust-laden air, had caused seizure of small bearings and gears used in the first aircraft instruments. As a result, controlled assembly areas were built.”

According to Austin, contamination control was first effected by good housekeeping practices, by segregating the work area from other manufacturing operations, and by providing a filtered air supply. With the advent of World War II, better filtration systems were developed, and air conditioning and room pressurization were considered essential. Personnel protective clothing was added later, as were air showers and personnel cleaning equipment.

But the principles of contamination control may go back even further, suggests international contamination control expert Dr. &#197ke M&#246ller. Many centuries ago, Chinese laquerwork painters created their own version of a laminar air flow bench to produce high quality laquerwork. They used the cleanest possible surrounding, Moller says, sailing out to sea with djonks to perform the work. — SG

Contamination threat prompts FDA to add warning to urokinase shipments

Judy Keller

WALKERSVILLE, MD — A CELL culture company claims that out-dated test methods, rather than an alleged contamination problem, led to a temporary halt of shipping a widely used clot-busting drug. BioWhittaker, a company supplying human tissue samples, checked its samples for various strains of hepatitis, including B and C, but the tests considered legal in Columbia, South America, are not approved in the United States by the Food and Drug Administration (FDA).

Chicago-based Abbott Laboratories, which uses the tissue samples in the manufacture of urokinase, was ordered to halt shipping its Abbokinase after the FDA raised contamination concerns in late November 1998. Following inspection of Abbott`s facility, FDA inspectors reported that some human kidney cells used in manufacturing Abbokinase were contaminated with hepatitis C or mycoplasma, which can cause walking pneumonia or strep throat. The company was allowed to resume shipping January 26, but the FDA notified healthcare professionals that there is a small danger of infection from using the drug, and to use caution in prescribing it. Abbott was ordered to put this warning in the labeling for the drug.

Additionally, the FDA on February 10 approved a more specific test to check blood for the hepatitis C virus. The test, made by Chiron Corp., is more sensitive to antibodies to the virus and can help pick out infected blood that has passed other tests. The FDA`s current screening tests were put into effect in July 1992. BioWhittaker was using tests that dated back to 1978 standards, rather than the 1992 recommendations. The newest tests are even more sensitive than the ones instituted seven years ago.

“It`s not a contamination problem,” contends Noel Buterbaugh, president of BioWhittaker. “We do screen material at the source, and Abbott screens it again when they receive it. We simply used an out-moded test. It`s the first time in 25 years we`ve ever had a problem like this. We are now going to use two tests to check for infections — the one we were using and the ones the FDA has told us to use. I`m confident we won`t have any more problems.” Buterbaugh says he could not give more detailed explanation because the FDA is still investigating the matter.

In a December 9, 1998, letter, Abbott informed customers of a temporary inability to ship the drug. The company sent the letter on its own initiative and not at the request of the FDA. In turn, the FDA was swamped with inquiries about the shutdown, and put up a web page to respond, listing alternatives to Abbokinase, or urokinase, as the drug is generically known.

The FDA`s Center for Biologics Evaluations and Research (CBER) evaluates lot release protocols for each lot of Abbokinase prior to its release to the public. During inspections at Abbott, FDA officials saw “significant deviations from current good manufacturing practices (cGMP),” according to the agency statement published on the Internet.

In addition to potential hepatitis B and C contamination, an eight-page FDA report commonly known as a “Form 483” lists other alleged problems. These include improper storage of samples, compromise of sample sterility, lack of testing for contaminant at certain stages in the manufacturing process, and failure to inform its supplier that some samples were contaminated with hepatitis B. The form also lists several documentation concerns.

Among the report`s claims are the following alleged problems:

Only one study was done to evaluate HIV inactivation by heat treatment.

Some human neonatal kidney (HNK) cells used during 1997 and 1998 were not tested for hepatitis C.

Some lots of HNK were contaminated with mycoplasma.

Some samples of HNK were taken from donors with fatal abnormal chromosome defects.

HNK cell culture supernatant (substance floating) is harvested daily and placed into a chilled tank where it is stored for a week before processing. No tests are performed to check bacteria, endotoxin, mycoplasma, or viruses at the end of this hold period.

HNK cells received by Abbot prior to implementation in 1991 of HIV and HILV-1 testing of neonates` blood are stored in the same liquid nitrogen tanks as cells tested under current procedures.

Storage tanks exceeded temperature specifications.

Sterile Abbokinase Open Cath (Abbott`s brand of urokinase used to clear catheter tubes) remains unstoppered for up to four days while being purged with filtered, compressed air. Open product vials are stored in covered trays, in aseptic transfer carts in Class 10,000 areas. No routine environmental monitoring is done to ensure open vials are maintained under Class 100 conditions during the hold period.

Some lots of the drug were rendered unsterile after a power failure and these lots were re-processed without process validation.

Problems with printed expiration dates occurred due to a 1995 human error in creating the label format. The situation went uncorrected for three years.

“I can`t answer each and every point in the report because the matter is still under investigation by the FDA,” says Melissa Brotz, spokeswoman for Abbott. “Cells that tested positive for viruses were not used and were destroyed. They were never used in manufacturing the drug.” She adds that the company worked closely with the FDA to secure release of Abbokinase and provided a written response to inspection findings in late November 1998.

She also notes that Abbott detected the contaminated samples in routine tests — tests of samples that had been certified clean by BioWhittaker. The FDA report indicates there is an issue with the documentation on how Abbott notified BioWhittaker of the contaminated samples.

In its January 25 warning letter to healthcare providers, the FDA warns that currently available lots of Abbokinase carry an unknown risk of infection of hepatitis C and a variety of infectious diseases, including tropical diseases. The letter claims that Abbott`s testing of samples from its supplier indicates that the supplier did not consistently or reliably perform screening.

But Buterbaugh claims the FDA simply doesn`t approve the kind of testing BioWhittaker conducted.

The FDA`s letter further states that neither the mothers nor the neonate donors were tested for hepatitis C virus (HCV): “Abbott has recently instituted a test of HCV in the kidney cells used in the manufacture of Abbokinase and negative test results have been obtained for currently available lots. However Abbott has not validated this test.”

The letter also warns, ” Prior to use in the manufacture of Abbokinase the kidney cells were harvested, stored and handled in a manner that may have permitted contamination with infectious agents.” According to the letter, Abbott used a viral inactivation process that substantially inactivates HIV and HCV in other biological products, but which “has not been fully validated for viral inactivation of Abbokinase.”

Continued production

Although the FDA refused to release any lots of the products during the investigation, company officials confirmed that Abbott continued to manufacture the drug, hopeful that they could begin to ship again and in anticipation of replenishing depleted hospital supplies. According to an FDA statement, Abbott agreed to beef up its safety measures and to update its labeling of the drug to include the information regarding the potential risk for infectious diseases. Major U.S. hospitals reported shortages of Abbokinase by the middle of December, about two weeks after the shutdown. By mid-January, many clinics and hospitals were out of the drug, and some physicians were angered that the FDA had halted shipments.

One of them was Dr. Kenneth Ouriel, chairman of vascular surgery at the Cleveland Foundation Clinic in Cleveland. “There is a small risk of viral contamination of this drug. The process of making it involves heat that would kill any contaminants, ” says Ouriel. “And, if the FDA was so concerned, why didn`t they recall the lots that were out there?” he asks.

Lenore Gelb, FDA spokeswoman, had this ready answer: “There was no need for a recall. There were no reports of anyone becoming infected from taking Abbokinase,” she says. However, she adds that doctors might not have recognized a connection between infections and drug usage.

Urokinase has been commonly used for about a decade to treat patients with life-threatening blood clots in the heart or lungs, as well as patients suffering strokes. It is also used to clear tubes used in kidney dialysis and chemotherapy. The manufacturing process used to make Abbokinase involves taking kidney cells from miscarried fetuses and putting them in a growth medium in a controlled environment. The resulting substance given off as the cells grow is urokinase. Many European drug manufacturers make urokinase from vast amounts of human urine, but the proprietary Abbott Laboratories method is faster and cheaper, claim industry sources. Ouriel says that the FDA does not certify the drug for use in clearing clots in the legs, although he says about a decade of use nationwide shows that it is extremely effective for this.

More than 250,000 people receive the drug Abbokinase or urokinase each year in the United States, Ouriel says. Each year more than 60,000 people die of pulmonary embolisms, or blood clots on the lung. About 600,000 pulmonary embolisms occur yearly. The Cleveland Foundation Clinic is the third-largest user of the drug worldwide.

“[Urokinase is] so effective that it is the drug of choice, the standard of care when there`s a blockage in a vein or artery in the leg. It`s not just for pulmonary embolisms,” Ouriel explains. Other clot-busting drugs such as Streptokinase or t-PA [tissue plasminogen activator] cause severe bleeding and allergic reactions. Those are drugs we used 10 years ago. Urokinase is better.”

Ouriel says that in discussions with Abbott and with the FDA, he learned that thousands of doctors nationwide were upset about the temporary shortage. He says the FDA told him it had as many as a thousand calls within days of the shipping shutdown. Ouriel is one of the principal investigators of a study that concluded using urokinase could save the leg as effectively as surgery when a patient has a blocked artery. The study, the largest to date that compares a clot-busting agent to surgery in patients with arterial blockages, was reported in the April 1998 issue of The New England Journal of Medicine. Abbott Laboratories funded the study.

However, the FDA`s January letter warns healthcare providers that urokinase is not certified for this use and urges reporting adverse reactions or infections resulting from the drug to its MedWatch program at 1-800-FDA-1088.

IEST division restructures working group hierarchy

Mt. Prospect, IL — The Contamination Control Division of the Institute of Environmental Sciences and Technology (IEST) is soothing its growing pains by restructuring the Working Group program into more manageable committees.

According to a report recently presented by the Division`s technical vice president, Bob Spector, five committees have been created, with a committee chairperson assigned to each. Spector says Working Group chairs will now report to these committee chairs as their first point of contact. The committee chairs will report into the chair of Standards and Practices.

“This approach will allow us growth in several areas at the same time,” Spector wrote in his report. “The primary function of these (committee chairs) is to be sure that the Working Groups within their respective committees will continue to move forward to the completion of their assigned tasks. We have far too much at stake as a major document producer in support of ISO/TC 209 to let this run amuck.”

Committee 1/Filtration will be chaired by Donna Kasper of Hollingsworth & Vose. Working Groups include WG-001: HEPA and ULPA filters; WG-002: Laminar flow clean-air devices; WG-006: Testing cleanrooms; WG-007: Testing ULPA filters; WG-019:Qualifications for agencies and personnel engaged in testing; WG-021: Testing HEPA and ULPA filter media; WG-034: HEPA and ULPA filter leak tests; and WG-100: Federal Standard 209.

Committee 2/Operational Products will be led by Nora Sylvestre of W.L. Gore & Associates. Working Groups include WG-003: Garment system considerations; WG-004: Evaluating wiping materials; WG-005: Cleanroom gloves and finger cots; WG-020: Substrates and forms; WG-025: Evaluation of swabs; WG-032: Packaging materials.

Committee 3/Procedural will be led by Bob Giroux of Certifab Inc. Working Groups include WG-013: Calibration of equipment; WG-014: Calibrating particle counters; WG-018: Cleanroom housekeeping; WG-022: Electrostatic charge in cleanrooms; WG-026: Cleanroom operations; WG-027: Personnel in cleanrooms; WG-029: Automotive paint spray.

Committee 4/Facilities will be led by Don Lutz of Dryden Engineering Co., Inc. Working Groups include WG-012: Cleanroom design; WG-024: Vibration in microelectronics facilities; WG-028: minienvironments; WG-030: cleanroom electrical systems; WG-033: Environmental code and definitions.

Committee 5/Environmental Control will be led by Chuck Berndt of C.W. Berndt Associates. Working Groups include WG-008: Gas phase adsorber cells; WG-016: Non-volatile residue in cleanrooms; WG-017: Ultrapure water; WG-023: Microorganisms in cleanrooms; WG-031: Outgassing performance criteria.

The Governmental Standards group will continue to be led by Joyce Steakley of Lockheed Martin.

Al Lieberman: Father of the particle counter

Judy Keller

Editor`s note: This is the seventh in a series of articles celebrating the accomplishments of the distinguished members of the CleanRooms Hall of Fame.

Widely recognized as the “father of the particle counter,” Alvin Lieberman`s contribution to the cleanroom industry extends far beyond his technical expertise and his extensive research.

“Al is approachable, extremely knowledgeable, and any time in the last 19 years that I can think of, he has always had time to give me an answer whenever I had a question,” says Bob Spector, technical vice president of contamination control for the Institute of Environmental Sciences and Technology (IEST). “Sometimes people who are as much of an expert as he is are above just talking to people. But he`s willing to share information.”

Lieberman says that those in the cleanroom industry need to share their data and expertise with each other, as well. He calls for pharmaceutical companies to learn from semiconductor cleanroom designers and vice versa.

He received a master of science degree in chemical engineering from Illinois Institute of Technology (ITT) in 1949. He is an engineering consultant for Particle Measuring Systems Inc., of Boulder, CO, where he had been a technical specialist from 1983 to 1985 and from 1987 to 1992. He was chief scientist at Hiac/Royco Instruments from 1968 to 1983 and from 1985 to 1987, formerly of Menlo Park, CA, now of Silver Spring, MD.

From 1951 to 1968, he was with the ITT Research Institute doing research and development on particle physics and powder mechanics. From 1949 to 1951, he was research associate at Alfred University, New York, working on cement development for high temperature turbine blade use. This research, which involved the mixing of powdered metals and ceramic glazes, led him to later work in the particle-measuring field.

Lieberman had been involved in the development of many standards for particle measurement instruments and cleanrooms, including Federal Standard 209. He is a US delegate to the Airborne Particulate Cleanliness working group and to the Measurements and Metrology working group of the ISO TC/209 Cleanroom Standards committee. He is the convenor of the working group on Single Particle Light Interaction methodology of the ISO TC/24/SC4 Particle Characterization Committee. In addition to being inducted into CleanRooms` Hall of Fame, he has received the Whitfield and Seligman awards from IEST, and the Hananer Award from the Fine Particle Society.

Lieberman is active in several technical societies concerning particle technology and contamination control. He has written more than 100 technical publications about particulate systems and con tamination measurement and control, has co-edited a book on liquid-borne particle measurement, and is author of a book on cleanrooms and contamination control.

Judy Keller is a freelance writer in Milford, NH.

Hot topic

Paul M. Fitzgerald

President and chief executive officer

Factory Mutual Research Corp.

Norwood, MA

To the Editor:

The article “Cleanroom fire-safety debate heats up” by John Haystead, which appeared in the April 1998 issue (CleanRooms, page 1), was informative and balanced. However, I would like to clarify Factory Mutual`s position and approach to cleanroom fire safety, and comment on some of the issues raised:

The Fire Propagation Index or FPI (mistakenly referred to in the article as the Fire Protection Index) represents the rate at which material becomes involved in a fire. A material with an FPI of 6 or less will not propagate a fire beyond the ignition zone.

The recent severe loss experience in Asia was cited as being the driver of Factory Mutual`s approach. In fact, the fundamental research initiative that led to the development of performance measures such as the FPI began in 1985. Concern over the cleanroom environment was one of the major reasons for undertaking this initiative even back then. More recently in 1994, because of U.S. loss history and loss potentials, we became even more concerned about cleanrooms. The more recent Asian experience just confirms that these concerns were justified.

We share the industry`s concerns about the process compatibility of materials meeting the 4910 FM criteria. To address this, Factory Mutual Research Corp. (FMRC) and SEMATECH have initiated a combined project to develop comparable indices for leaching, outgassing and chemical resistance. It is expected that the results of this joint project will provide further guidance of their acceptability and use.

The article commented that these new materials cost up to five times more than ordinary materials. A recent cost analysis by a manufacturer, however, concluded that these new materials would comprise a maximum increase of about 4 percent of the cost of a fully automated wet bench. Thus, the use of these high-performance materials would have a very minor impact on the overall cost of a tool.

Questions were raised on the repeatability of results from the test apparatus we use. During its early stages, we experienced some setbacks in replicating our original instrument. These setbacks were overcome and today, we have two instruments that provide consistent, repeatable results.

The portrayal of Factory Mutual`s recommendations on the use of fire suppression systems was not clear. First we have always recommended that wet benches and other processing tools be constructed of non-combustible materials. The use of fire suppression systems is a less desirable alternative because of the potential for a large fire with greater resultant damage occurring. Second, our objective in developing materials that meet our 4910 test criteria was aimed at providing the industry with an alternate to providing suppression systems. These materials provide nearly all of the advantages of non-combustible materials, while retaining the process and cost advantages of the combustible materials currently used in this sensitive, dynamic occupancy.

Finally, we welcome other testing laboratories to adopt the 4910 Standard for testing these materials. We have submitted the standard and apparatus for public recognition. We are finalizing negotiations with a manufacturer to produce the apparatus. Copies of the 4910 Standard are available to the public by contacting the FMRC Technical Information Center.

Cleanroom expert brings issue of human contamination control to life

By Tammy Wright

Editor`s Note: This is the third in a series of articles celebrating the accomplishments of the distinguished members of the CleanRooms Hall of Fame.

During a career that spanned more than three decades, Eric S. Burnett, Ph.D., made numerous contributions to the cleanroom industry. The retired environmental consultant is probably best known, however, for fostering and promoting a true understanding of the relevance of available testing in the fields of contamination control.

“Eric was able to educate the industry about what really matters to cleanrooms,” says Chuck Berndt, one of Dr. Burnett`s long-time professional associates and a current member of the Editorial Advisory Board for CleanRooms magazine. “He was able to sort out testing that was actually useful, such as particle counting and measuring static charge and ionic residuals. He also brought to life (the issue) of human-sourced contamination.”

Dr. Burnett`s work has had a far-reaching impact on many companies and industries. His professional career started at British Aerospace Corp. In 1963, he moved to RCA Astro-Electronics Division in New Jersey, where he was a section leader developing sensor systems for polar-orbit and geostationary meteorological satellites for NASA and the U.S. Department of Defense (DOD). Dr. Burnett went on to manage advanced manned spacecraft systems studies and sensor system integrations of earth-observation satellite programs at General Electric Co. He left that position in 1967 to join TRW Systems, Inc. where he again developed sensor systems for manned and unmanned spacecraft for NASA and the DOD.

In 1972, Dr. Burnett`s interests broadened. He began developing and installing air and water pollution control systems as an environmental engineer for Environmental Services, Inc. That position led him to Aratex Services, Inc., where he spent almost six years developing air and water pollution control systems and energy conservation systems, including a large-scale solar energy system. In 1990, Araclean Services hired him as a group technical services manager. In that role, he supervised the development and evaluation of new materials, instrumentation and cleaning processes for the microelectronics, pharmaceutical and bioengi neering industries.

In honor of his accomplishments, Dr. Burnett was inducted into the CleanRooms Hall of Fame in 1993. CR

Latex gloves under fire again

By Myron Struck

Washington, D.C. — Latex gloves, a staple product in health care and cleanrooms industries, have come under attack by a public interest consumer watchdog group that contends the cornstarch used to make them easier to put on is an allergen causing more problems than it solves.

The attack, which calls for the U.S. Food and Drug Administration to issue a ban on powdered latex gloves, comes just months after the National Institute of Occupational Safety and Health issued a warning that cautioned workers exposed to latex gloves and other products containing natural rubber latex that they may develop allergic reactions such as skin rashes; hives; nasal, eye, or sinus symptoms; asthma; or even shock.

The warning has spurred the industry, and at least one manufacturer has moved to launch a new line of products, called Sterile N-DEX, which is based on a non-latex procedure glove that is nitrile based.

George Mack, general manager of Best Manufacturing (Menlo, GA) says: “It`s rare when you can truly say something is revolutionary, but this introduction comes as close as you can get.” The nitrile glove is the first non-latex sterile procedure glove for the medical industry, according to Best. The formal roll out in January followed a limited introduction at the Health Industry Distributor Association`s trade show in Chicago recently.

An estimated 2 percent of the general population and up to 21 percent of healthcare workers are sensitized to latex allergens. From August 1996 to August 1997, the FDA received 305 reports of allergic and anaphylactic reactions to latex gloves. In Oregon, a nurse reportedly died from latex shock. Fluid from a rubber tree is used to make latex products, and chemicals are added in the manufacturing process.

The attack on the powdered, latex-based gloves was launched by Public Citizen, a Washington, D.C., public interest group affiliated with noted consumer advocate Ralph Nader.

On January 7, Sidney Wolfe, the medical doctor who directs Public Citizen`s Health Research Group, Dr. Timothy Sullivan, Professor of Medicine at Emory University School of Medicine and Head of the Subsection of Allergy and Immunology at the Emory Clinic, and Public Citizen staff researcher Christine Dehlendorf filed a formal petition calling on the FDA to ban the powdered latex gloves as a “serious, unnecessary menace in hospitals and other health care facilities all over the country.”

“Safer alternatives such as powder-free gloves are easily and currently available, but too many hospitals are willing to cut corners and risk the health of their patients and employees,” Wolfe said in the petition to Dr. Michael Friedman, the lead deputy commissioner at the FDA. “As of last year, 26 percent of surgical gloves used in the United States were powder-free proving that this safer alternative is quite feasible.”

Many of the alternatives have been decried, however, as ineffective or subject to tearing as a result of not having a smoothing agent to allow easy use. That handicap led to the technological development at Best Manufacturing, which focused on a different medium than latex.

The Public Citizen petition calls on the FDA to ban cornstarch powder in the manufacture of latex surgical and examination gloves under section 516 of the Food Drug and Cosmetic Act, 21USC 360(f). The FDA`s reaction to the Public Citizen petition has been reported as sympathetic, but the government agency is opposed to an outright ban, pointing to the lack of alternatives.

Public Citizen cites epidemiological studies that show cornstarch can “inflame wounds and promote infection, and cornstarch-induced adhesions can produce intestinal obstruction, pelvic pain and infertility in patients” operated on by medical personnel wearing cornstarch-powdered surgical gloves. In addition, cornstarch acts as a carrier for latex protein/allergens, resulting in rhinitis, asthma and anaphylactic shock.

“Many health care workers have experienced such serious reactions to latex they have been forced to give up work,” Public Citizen said, complaining that the government`s 1997 warning, which goes into effect this September, is not strong enough. The lobbying group says that these warnings “are routinely ignored by the vast majority of health workers.”

Several major hospitals, including those at Harvard University, Boston and Miami have switched to latex-free gloves.

“If the FDA is to perform as a public health agency it must more definitively protect the millions of patients and tens of thousands of workers already allergic to latex,” Wolf said. “Unless definitive action is taken, not only will those people already allergic to latex continue to suffer serious, often life-threatening reactions, but the number of affected people will continue to rapidly increase as more and more exposure to airborne, latex-laden glove powder occurs.”

The Public Citizen report suggests that some surgeons are reluctant to use powder-free gloves because they perceive that they are more resistant to donning than powdered gloves. The group also says that concerns about the potential for leaks of powder-free gloves are ad dressed by the FDA`s quality control testing of medical gloves. The FDA`s guidance manual for manufacturers of medical gloves (issued December 12, 1990) describes the water leak method of testing used to ensure that all medical glove manufacturers meet a standard level of quality.

Hospitals have become concerned, in part because of potential concerns from workers and from patients. At the Mayo Clinic, a new innovative strategy to purchase gloves that markedly reduced the cost was developed. Since December 1993, Mayo Clinic has only used gloves with a low-latex allergen protein content.

Whitfield opens door for cleanroom industry

Lisa A. Karter

Editor`s Note: This is the second in a series of articles celebrating the accomplishments of the distinguished members of the CleanRooms Hall of Fame.

In April, 1962, Time magazine dubbed Willis Whitfield “Mr. Clean.” Indeed, he was deserving of the title because it was his idea that led to the Whitfield Ultra-Clean Room, the predecessor of today`s cleanroom.

“The idea was so simple, that some place, some time, somebody must have had this idea before,” Whitfield said in an interview with CleanRooms in 1995. It was his idea for a laminar flow cleanroom that earned him induction into the CleanRooms Hall of Fame in 1990.

A Texas-born physicist, Whitfield was part of a group that was responsible for helping solve problems in advanced assembly and manufacturing of electromechanical weapon components at Sandia National Laboratories (Albuquerque, NM). In 1959, U.S. Gage, a manufacturer of mechanical weapon timers, reported a cleanroom problem and Sandia had supplied the company`s cleanroom. Yes, a cleanroom existed in 1959, but it was merely an air conditioned room. That year, Whitfield first developed his concept for the laminar flow cleanroom. It wasn`t until years later that it became a reality.

Whitfield`s idea was to supply air to a cleanroom in a unidirectional flow instead of moving the air randomly about the room. In 1961, a model of the Whitfield cleanroom was built. It was an 8-by-10 foot room with air entry through the ceiling and exit air leaving through the floor. This design allows over 600 air changes per hour compared to 20 air changes per hour of previous clean, air conditioned rooms. In 1964, the idea was patented and the rest is history.

Whitfield began his career in 1952 at the U.S. Navy`s Naval Research Laboratory`s solid rocket fuels and motors R&D project. In 1954, he was hired as a nuclear physicist at Sandia. Three years later he moved into a special projects group. From 1967 to 1976, Whitfield was division supervisor of Sandia`s Applied Sciences Division conducting research for NASA. From 1977 to 1984, he was division supervisor for the Isotopic Sources and Hot Cell Application Division. Whitfield also helped develop Federal Standard 209 in 1963.

Whitfield`s contributions to the contamination control community include working on the American Association for Contamination Control in the 1960s. He was appointed to the National Academy of Science`s Committee on Airborne Bacterial Control in Hospital Operating Rooms in 1974. He received three patents for his cleanroom work, and the Individual Scientific Technical Achievement Award by the American Association for Contamination Control as well as the Holly Medal for his laminar flow cleanroom principle from the American Society of Mechanical Engineers among several other honors and awards.

In 1984, Willis Whitfield retired.

Fluid seal inventor makes mark with filters

By Lisa A. Karter

Editor`s Note: This is the first in a series of articles celebrating the accomplishments of the distinguished members of the CleanRooms Hall of Fame.

He probably didn`t know it then, but in 1947, Adrian R. Allan Jr.`s love for sailing and a fascination of woodworking helped him carve an important role for himself in the cleanrooms in dustry. This was the year he found ed Flanders Filters, Inc. (Washington, NC).

Indeed, Allan was a pioneer, an entrepreneur and an inventor. He created the fluid seal, an interface be tween HEPA and ULPA filters and their supporting grids. He was also re sponsible for the development of separatorless HEPA/ULPA filters. Flanders Filters was the first company to produce its own filtration media, which led to the development of unique processes for the manufacture of separatorless, self-supporting filter elements.

Allan`s interest in the art of sailboat building spurred him into constructing a three-story mill. While completing a woodworking job for Brookhaven National Laboratory, he became interested in wood frame filters required for radioactive containment. The wood-framed HEPA filters were used in nuclear facilities to prevent airborne particles from escaping into the atmosphere. In the early 1960s, Allan decided to make not only the wood frame but also the filter medium — a non-woven matrix of very fine microfibers.

The fluid seal was invented during a time when Flanders was using a large rotating oven, which looked similar to a merry-go-round, to cure the adhesive from HEPA filters. During a visit from a Western Digital engineer in the mid-1960s, the question of bypass leakage around HEPA filters was discussed. It was during their conversation that Allan thought of the round cover on the rotating oven. The cov er was sealed at its rim by a knife edge im mersed in a trough of water, which ran around the sidewalls of the rotating oven. As the oven rotated, the heat was retained. During the meeting with the Western Digital engineer, Allan thought a fluid interface might solve the problem of bypass in vertical downflow cleanrooms. This technology earned two patents and has since been offered by most filter and cleanroom construction companies as the only way to successfully prevent bypass leaks around HEPA filters without constructing massive mating flanges that are often used in nuclear installations.

Allan also built the first (and only) glass papermaking process to produce self-supporting, also called separatorless, HEPA filter media. Allan wanted complete control over the most critical component in his product, the filter medium, and demonstrated his entrepreneurship by constructing a small paper-making machine that produced flat-sheet media. Once Allan perfected the production of media in-house, it occurred to him and his production manager that the material might be formed into something other than a flat sheet when in a wet state. The result was a machine that corrugated the wet glass paper as an integral step in the Fourdrinier paper-making process. The paper was pleated into a self-supporting filter element. Although the process is no longer in service today, it was the progenitor of several techniques and machines that are still in use today.

In recognition of his contributions to the contamination control industry, the late Adrian (Sam) Allan Jr. was inducted into the CleanRooms Hall of Fame in 1994.

Centrifugal air sampler

Biotest Diagnostics Corp. introduces an enhanced version of its Standard RCS Centrifugal Air Sampler which is used to measure the concentration of airborne microorganisms in ambient air. Upgraded features include an easy-to-read LED panel for selection of sampling times; red, alarm LED lights to indicate impeller blade obstruction and low battery voltage; automatic shut-off during non-use; and an optional infrared remote control. Additional information is available upon request.

Biotest Diagnostics Corp.

Denville, NJ

(800) 522-0090 or (973) 625-1300