Brought To You By…Cleanroom Technology
By John Haystead
Although a select-few, advanced-technology industries like semiconductors and pharmaceuticals have been the principle drivers behind the advancement of cleanroom and contamination control technology, a much greater and growing group of other industries is now making use of its many benefits. Some of these industries may be surprises, others not, and in some cases, it may be that our expectations of the extent to which contamination control practices are employed are overestimated. One thing is clear, however: contamination control is big business and getting bigger.
The healthcare industry may be one example where our perception of contamination control is actually greater than the reality. “Most operating rooms are constructed to the equivalent of a Class 10,000 cleanroom, a situation which really hasn`t changed much in recent years,” says Steve Mynsberge, construction director for McCarthy (Phoenix, AZ), a builder of medical-care facilities as well as ultraclean facilities for the semiconductor and pharmaceutical industries.
One of McCarthy`s most recent healthcare projects was the Kaiser Permanente Baldwin Park Medical Center (Baldwin Park, CA), a $119 million, 740,000 ft.2 facility that includes a 240-bed patient tower, four-story clinic and a separate central-service plant. “Generally, the nearest we get to cleanroom protocols in hospital construction is the operating room space,” says Mynsberge, “although even here, the requirements really don`t compare to the standards of the semiconductor and pharmaceutical industries.”
A lot of attention is paid, however, to the cleanability and maintainability of operating rooms as well as to recovery rooms and other critical-care spaces. For example, solid-PVC sheet flooring, epoxy paints, and stainless steel are used throughout these areas because of the durability of the materials and because they don`t absorb chemicals or body fluids.
Hospital air supply systems, air change rates and air balances are also carefully regulated. In addition to the use of laminar-flow air diffusers and HEPA filters, operating rooms are kept at positive pressure to the rest of the facility, while isolation rooms for patients with contagious diseases must be maintained at negative pressure. Precautions are also taken during construction to keep air supply systems somewhat contaminant-free. Duct ends are kept continuously covered and the segments of the system that serve high-cleanliness areas are evacuated by a high-pressure vacuum system upon completion. Significantly, however, because the primary design concern for an operating room is accessibility as opposed to contamination control, standard automatic doors are generally used as opposed to a vestibule or air-shower arrangement.
Although not quite to the level of a high-purity cleanroom system, special care is also taken during hospital construction to control contamination in the medical-gas systems. Factory-cleaned-and-capped copper piping is used throughout and a nitrogen purge is maintained on the system as each fitting and valve is assembled.
Unlike the tightly monitored pharmaceutical industry, there`s no federal-agency responsible for monitoring hospital construction or operation–a job generally handled at the state level. In California, for instance, hospital construction comes under the jurisdiction of the Office of Statewide Health Planning and Development (OSHPD).
OSHPD`s program of planning and inspection requires an inspector-of-record hired by the owner and answerable to the state to perform continuous supervision and inspection of the job. As part of the state licensing process, hospitals must provide volumes of data on procedures relative to everything from controlling contamination, to emergency procedures, to visitor management.
While it seems there`s still significant room for improvement, some contamination-control progress may be in the offing for healthcare facilities. For example, Mynsberge says, “OSHPD has been rapidly evolving over the past eight to 10 years with increased attention to contamination control.” Medical gas systems are one example. Following the refinement of installation procedures at one hospital, OSHPD issued an industry bulletin making the procedures a part of its standard for medical-gas-system installation.
Food Processing and Packaging
Microbial contamination has always been a major concern for the food industry, particularly for foods with high water content or those that don`t use preservatives. With the exception of the meat and poultry industries, which are regulated by the Department of Agriculture, the FDA is responsible for monitoring food processing and safety.
Within the FDA`s Center for Food Safety and Applied Nutrition, Dr. John Kvenberg, manager of the Hazard Analysis and Critical Control Points (HACCP) program (Washington D.C.), is looking at a new approach to food security. Unlike standard FDA practices which rely on on-site visual inspections, HACCP will instead encourage companies to institute and maintain a record-keeping and documentation system for continuous quality control. The HACCP system will rely on industry to identify, analyze and provide for continuous monitoring of the critical elements of their various processes.
In January of 1994, HACCP began with proposed new regulations for the processing and packaging of seafood products. These regulations are currently in final review and the results are expected to be published this summer. For the other food areas they regulate, the FDA published an Advanced Notice of Proposed Rulemaking (ANPR) to solicit information from industry on what the HACCP regulations should contain. The comment period to respond to the solicitation closed on December 2, 1994, and the results are currently being reviewed. Industry volunteers are also being solicited to participate in ongoing HACCP pilot programs. Information collected from these exercises will be included in the development of the new regulations.
Kvenberg emphasizes that HACCP is a voluntary effort. “Although we interact with them, industry is responsible for writing their own plans of operation.” The FDA provides no specific research funding to industry, but does sponsor research with industry and academia through the National Center for Food Safety in Chicago which is affiliated with the Illinois Institute of Technology.
Spurred in part by outbreaks of disease traced back to the dairy industry such as post-pasteurization contamination of milk products during filling or packaging operations, the FDA, in addition to certain state programs, has been charged with monitoring the safety of dairy products. Noting the recent widely publicized case of ice-cream mix re-contaminated in a transportation vehicle, Kvenberg says, “these documented outbreaks mean that the dairy industry is one food area that should definitely pay attention to new contamination control practices and technology.”
According to Dr. Tom Gilmore, technical director of the Dairy & Food Industries Supply Association (Rockville, MD), the dairy industry does, in fact, recognize the importance of contamination control throughout its processes. “There`s a definite trend toward enclosing dairy and food processing equipment within controlled environments,” says Gilmore, who also points to the fact that a growing number of U.S. companies are getting involved in aseptic packaging of dairy and other products. “The technology is definitely here.”
Hershey Chocolate is one such company. Hershey packages its “Genuine Chocolate Flavored Drink” product in 8-oz. aseptic “bricks” at its plant in Savannah, GA. Although the product contains skim milk, it does not require refrigeration. Plant manager, Carole Rich, says Hershey acquired the plant in 1991 but believes it was the first low-acid (vs. high-acid products such as juices) aseptic process plant in the United States. Aseptic package technology was first introduced in the United States around 1982. Hershey`s Savannah plant is rated by the Interstate Milk Shippers (IMS) association, a requirement for the interstate shipment of milk products.
FDA`s Kvenberg feels that although the United States has been a world leader in developing and implementing technology to ensure a safe food supply, more than one segment of the food industry can benefit from improved contamination control processes. For example, one large developing industry is the prepackaged-salad industry that uses cleanroom procedures to package and distribute prepared vegetable products.
Says Kvenberg, “the whole concept of prepackaged, radiate-and-refrigerate foods is one area that should pay close attention because of the potential for bacterial introduction and temperature abuse in the distribution chain.” Noting that the frozen food industry is largely a heat-and-serve operation, Kvenberg warns, “if microbes are present at the time of packaging, there`s always a potential bacterial hazard should these products not be adequately reheated.”
In late November, the National Academy of Science identified food safety as one of its national R&D priorities and Dr. Kvenberg believes such initiatives will increase the number of opportunities the FDA and other agencies will have to cooperate and exchange technical information. For example, the USDA Food Safety and Inspection Service has introduced Technical Analysis Groups (TAG) that deal with all aspects of their products. Says Kvenberg, “we liaison with them on how to best build safety systems and evaluate new technologies.”
Beverage
Although breweries like Anheuser-Busch, Inc. (St. Louis, MO) are also required to meet FDA and other government agency safety standards, Bill Mallory, operations manager, Process & Product Development, Anheuser-Busch, Inc. points out that “the contamination control systems we`ve instituted to prevent beer spoilage have taken us well beyond the levels needed to deal with health risks to consumers.”
The U.S. brewing industry has always supplied its draft beer in kegs and barrels. However, because draft beer is non-pasteurized, it also always had to be kept at cold temperatures to prevent “beer-spoilage” organisms from attacking the product. Although not a hazard to health, these organisms would over time spoil the beer.
In the late 1980s, responding to market demand for draft products in cans and bottles, Anheuser-Busch began running tests at several of its breweries to determine the requirements for such a process. Clearly, explains Mallory, “the solution was to have all the problem organisms completely out of the product by the time it was packaged, but the `catch 22` was that these same organisms were also a by-product of the process.”
In addition to studying and benchmarking the sanitation procedures, cleaning-chemical usage, and environmental controls of European, Japanese as well as other U.S. brewers, the company also conducted studies to determine specifically how and where the organisms were getting into their product. “Eventually, we were able to isolate and concentrate on a set of critical control areas,” says Mallory, “one of which was clearly the environment surrounding our filling operation.”
Because the organisms were essentially thriving in the wet environment of the filling operation, the first step was to completely enclose the environment so that heat and humidity levels could be controlled. Anheuser-Busch`s enclosures are completely stainless steel structures with the filling equipment inside made of stainless steel as well. Plexiglass-type windows allow operators to observe the process.
Specially designed seals and other equipment had to be used in the enclosure construction because of the temperatures required for the hot-water sterilization process. A positive-pressure environment, air is passed through HEPA filters as well as bag pre-filters before being pushed down from the ceiling and pulled out through the floor of the room.
Within the enclosures, brewery personnel practice cleanroom-hygiene techniques wearing sanitary clothing, headgear, boots and gloves. Contamination control entry doors are also used along with sanitary footbaths. Recalls Mallory, “the original design called for enclosing the entire working area including personnel, but it was later learned that we were better off having vestibules and keeping the people out whenever possible.”
The study team identified incoming materials and utilities as another critical-control area which lead to improvements in their carbon dioxide and water utility filtration processes. Water is filtered through a 100-micron bag filter followed by a 0.5-micron membrane filter.
Mallory says that one of their biggest breakthroughs came with the installment of a `hazard-analysis` system around their critical-control points. “This gave us the assurances we needed that we were protecting our processes and working within our parameters.” The computerized hazard-analysis system continuously reviews all process data and either allows the filling process to proceed or requires a procedure to be corrected. For example, describes Mallory, “our sterilization procedure requires 20 minutes at 180°. If these conditions are not maintained throughout the procedure, the system will remain shutdown until the correction is made.”
Anheuser-Busch has a total of 13 breweries around the country, seven of which (15 operating lines) are now capable of running the aseptic packaging process developed for such products as “Michelob Golden Draft” and “Golden Draft Light.” Mallory says he has struggled somewhat with classifying the cleanliness level of their facility along the lines used by the semiconductor/ pharmaceutical industry, but, “for the most part, we`re close to 100,000.”
Mallory observes that the marketplace will ultimately dictate the future plans of Anheuser-Busch and the brewing industry as a whole, but the lessons and experience gained through the aseptic processing lines have really driven home the importance of contamination control throughout the system. “We`re still learning about the process and we`re continuously striving to make improvements, but we also have to consider what is strategically right for our business.”
In that regard, the company has no current plans for strict contamination control of an entire brewing facility, although they`re doing some minor overall air filtration. The reason is that not all of its beer lines require the same level of control and the company has concentrated its capital expenditures around the lines and processes that do. Mallory adds, however, “sometimes there appear to be points where things seem cost-prohibitive, but ultimately we react to our customers` needs.”
Tissue Engineering
Although often lumped into the broad category of biotechnology, tissue engineering is actually a small, but potentially very large, technology segment unto itself. As observed by Phil Anderson, director of engineering at Advanced Tissue Sciences (La Jolla, CA), “we`re actually growing living tissue, a process extremely susceptible to biological contamination at both the research and manufacturing stages yet one which requires absolute preventative protection. With live tissue, there`s no such thing as terminal sterilization.” Currently, the company has two tissue-engineered products in advanced clinical trials–Dermagraft (for diabetic foot ulcers) and Dermagraft TC (a transitional covering for severely burned patients).
No agency regulates the cleanliness levels of the ATS facility per se, although the FDA does monitor its adherence to procedures and practices. Interestingly, the ATS product is classified as a device under FDA regulations.
In the research phase for several years, ATS has just completed construction of a manufacturing suite which includes about 8,800 ft.2 of cleanroom laboratory. EnviroFlex (Orange, CA) designed and installed the facility which, according to Tim Marrs, Enviroflex cleanroom engineer, breaks down to 1,980 ft.2 of Class 100,000 and 6,820 ft.2 of Class 10,000 space.
The facility is actually a combination of several interconnected rooms and areas maintained at different cleanliness levels. Each area is segregated into different sections of the plant, and protocol includes a very-strict, one-way transit system of people and product through the facility. All personnel and materials exit the highest-level production area via a “departure corridor” which surrounds the entire laboratory complex and leads to a waste disposal, degowning and decontamination area. Once out, personnel cannot return to the production areas.
To enter the facility, all personnel go through part or all of a multi-level gowning procedure. Upon entering the general plant, everyone must remove their street clothes and put on a plant uniform. Uniformed personnel are then allowed into the general production and plant support area which is roughly Class 100,000, but to move into the higher classification (Class 10,000) areas, they must go through another full-gowning area including boots and head covers. Ultimate-level work is done in Class 100 hoods.
Although ATS does not classify its facility according to traditional categories, Anderson emphasizes that they are greatly concerned about non-viable particulate contamination. “We test both air and surfaces as well as personnel for both viable and non-viable particulates.”
The multiple-room facility is divided by function such as cell-processing and growth spaces. A unique aspect of the application is the use of cold rooms (5°C to store culture media for growing the product) and a warm room (37°C for growing the cells which will eventually be used to generate tissue). In all, 13 air handlers with capacities ranging from 4,300 to 7,000 ft.3/min, as well as an 80-ton chiller and 350-ton cooling-capacity water tower, are installed. Chandler Refrigeration (division of Heatcraft Refrigeration Products, Stone Mountain, GA) supplied the air-handling equipment which is computer-monitored for temperature and humidity and includes an alarm provision for notifying company officials at their homes in the event of a problem. Both cold and warm rooms are HEPA filtered and adhere to the standards of the rest of the environment.
Anderson sees tissue-growth becoming a significant industry in the future and expects ATS will expand its manufacturing capability as product sales increase. “We just built this facility and haven`t really put it into use yet. But, as we scale up and gain experience, we`ll be continually looking for specific areas for improvement.”
Automotive & Paint Spray Technology
According to Mike Byrne, process engineer, Chrysler Tech Center (Auburn Hills, MI), customer expectations for the automotive industry are much higher today than they were 10 or even five years ago. “There`s been a dramatic revolution in the automotive industry as far as taking contaminant-control seriously, continuous improvement, and getting a much better paint job on a first-time basis.”
At Chrysler Corporation`s St. Louis, MO assembly plant, one of 11 plants in North America, two parallel 600-ft. electrostatic color-painting tunnels are connected via a common contamination-controlled vestibule. Positive pressure is maintained from the paint shop to the vestibule and from the vestibule to the rest of the plant. To enter the paint tunnel, air flows through multiple levels of air filters including high-efficiency (90-95 percent at 1.0 micron) bag filters and exits via panel-filter/diffusers in the paint tunnel ceiling. The maximum allowable particle size is 3-5 microns.
The filtered air is driven down from the ceiling and through a grated floor in the booth carrying away any paint overspray or contaminants into a chemically treated waterwash below. In the manual zones of the tunnels, the downdraft is 100 ft./min. and 60-80 ft./min in the automated zones. The residual paint sludge is eventually converted into a material used in the making of roof shingles.
In addition to its color tunnels, Chrysler has installed a new contamination-controlled powder-finishing system for its Cirrus, Stratus and Neon models. After the auto body is phosphated and electrocoated, an epoxy-polyester powder is applied electrostatically for chip resistance and UV protection. An ionized blow-off system is used before and after the powder coating, and Chrysler is now also starting to work with a new two-stage blow-vac system as an alternative to the use of tackified plastic for lifting contaminants loosened by the blower.
Chrysler has also imposed very strict guidelines relative to the materials they use in their paint spray process, as well as for filtered water and compressed air. Paint is passed through a bag filter prior to application and in some cases, the company is using a specially designed vibration filter to trap contaminants.
Although some plants are more automated than others, workers are often required to be inside the tunnel facilities, and Byrne acknowledges that the company has found human contamination to be a critical factor–especially with waterborne paints and powder coatings. “Personal hygiene products such as deodorants and hair sprays are deadly to the defect rate and can ruin a system in very small amounts.” Chrysler is working to better educate its employees to the dangers of human contamination, and are also working closely with apparel suppliers relative to lint and fiber contaminants.
Haden Inc. (Auburn Hills, MI) is one of a few principle suppliers of large, turnkey paint finishing systems, primarily to the automotive industry but also to other general industrial markets such as heavy equipment and truck manufacturers. Steven Smith, Haden`s vice president of Business Development, notes that like hospital designers, “paint-spray customers often place more emphasis on their ability to clean the system and cleanroom than they do on the cleaning of the air itself.” Haden`s systems emphasize smooth surfaces and corrosion-free materials, although some customers will opt for less-expensive, aluminized steel instead of stainless.
Since January 1994, Textron Automotive Interiors Inc. (Farmington, NH), has been running its new “Flexible Bright/Liquid Bright” paint-spray operation in Class 100 cleanroom tunnels. A process, with the ultimate potential to replace chrome, the facility includes several hundred feet of conveyerized and segmented cleanroom tunnel, beginning at ambient and moving through Class 10,000 to 1,000, and finally to a significant portion of Class 100 space. Says Bob Sparling, Textron senior engineer, “without cleanroom technology, we flat-out wouldn`t be able to make our product. The automotive industry doesn`t want to see any spots or blips in paint greater than 1 mm, which is what you`ll get if something of 10-20 micron size gets underneath the primer and is bridged over with successive coatings of paint.”
Textron`s process is maintained at Class 100 wherever coatings are wet or hot (thermally tacky), and each segment of the tunnel is air-balanced with laminar-downflow air. No workers are allowed inside when the tunnels are active, but when access is required, they wear cleanroom smocks, hoods and gloves.
Although the process was designed and initially prototyped at its Automotive Technology (R&D) Center in Dover, NH, Sparling recalls that there were still significant challenges during the scale-up to production in both processes and equipment.
“The Textron facility is really a groundbreaker,” says Hank Craig, U.S. sales manager for Torrid Oven, who notes that the use of cleanroom technology in the paint-spray industry really only began about nine to 10 years ago when the automotive industry started using plastics for trim and fascia. “Usually, our spraybooths are Class 1,000.” Torrid manufactures plastic-paint finishing cleanrooms in the range from $4-$12 million including a 24-ft./min dedicated fascia line for the Rimply Division of DeComa International in Newmarket, Ontario. The Rimply facility is the highest-production plastics painting plant in North America.
Contamination Control Industry
Not surprisingly, another emerging market for cleanroom products and technology is the cleanroom industry itself. For example, Farr Company (El Segundo, CA), a manufacturer of air filtration systems and equipment, recently opened a 4,000 ft.2 cleanroom in Holly Springs, MS for HEPA, ULPA and MEGA filter production. Unlike many of the industries which companies like Farr supply, however, its own manufacturing facilities weren`t designed from the ground up for ultraclean manufacturing.
“We had a heavily-industrialized plant and, like most manufacturers, only a small, segregated area for manufacturing ultra-high efficiency products,” says Forrest Fencl, Farr`s director of worldwide marketing. “We usually didn`t have to worry too much about the cleanliness-level of the filter, because right after construction, a cleanroom would generally be 100 times dirtier. Before it could be used, the filters would have to run 36 hours or more, anyway, and be certified.”
In fact, neither customer demand nor contamination control was ultimately the driver behind Farr`s decision to move to a cleanroom manufacturing facility. Says Fencl, “in order of importance, the things that a cleanroom does for us are: tremendous consistency in air temperature, specific humidity and cleanliness. In other words, if you`re going to provide a controlled environment, why not go ahead and make it clean as well?”
Ultimately, the benefits to Farr have been in productivity. Says Fencl, “what we`ve basically achieved is higher quality product and higher product yield without really changing the process.”
The company now reports a much higher degree of predictability in terms of how its adhesives and potting compounds will react, which in turn has given it greater flexibility on the materials it can use. “Curing in 95 percent relative humidity/90° air is a lot different than 72°/50 percent RH air,” observes Fencl. Farr is assembling, testing and bagging in the clean environment.
Fencl says the company originally only set out to install a Class 50,000 environment, but eventually set their goal at 10,000. In the end, says Fencl, “we can claim 10,000 under the worst conditions and mostly we`ve gotten under 1,000 even in operation.” Designed and constructed by Lepco Inc. (Houston, TX), the facility includes a separate Class 100 laser test section.
A residual benefit of the cleanroom environment has been an increase in worker productivity. Farr`s employees are now all garmented and gloved, although boots are not required because of the softwall. “We believe by providing this real-clean environment, we`ve achieved a 20-30 percent improvement in the way people treat the product,” says Fencl.
Fencl sees a definite trend in the contamination control industry with more and more product companies moving to cleaner manufacturing environments. Pointing to the general trend toward ISO 9001 standards and quality improvement, Fencl believes that if the approach is made available, customers will start to ask for it, then require it. “Besides,” says Fencl, “it`s in the best interests of the manufacturers, period. In terms of total life-cycle costs, a cleanroom is a bargain.” n
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Quality-critical applications for advanced cleanroom technology range from beer-making to automobile painting finishing. Hospitals and emerging biotechnology industries are also learning new ways to apply modern contamination control techniques to their operations.
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Left: Air-handling equipment installed above multiroom, tissue engineering facility; Top Right: Kaiser Permanente Baldwin Park Medical Center; Bottom Left: “Cirrus” automobile moves through Chrysler`s Sterling Heights, MI paint-spray line.
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Operating room at Kaiser Medical Center (Baldwin Park, CA). In addition to laminar-flow air diffusers and HEPA filters, contamination control practices are also implemented in the construction of the facility`s medical gas systems.
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Anheuser-Busch, Inc.`s Cartersville, GA brewery. The east side of the enclosure is shown where discharge of process flow after filling and crowning of product occur.
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The Chrysler Cirrus waterborne paint system is used to reduce emissions of volatile organic compounds and to improve the car`s exterior appearance. Using an electrostatic application of the waterborne base coat improves the transfer efficiency while powder anti-chip protection is provided for hoods and sills.
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Ultra-pure paint-spray processes like Textron Automotive`s “Flexible Bright/Liquid Bright” may potentially replace chrome finishes.
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Farr Company (El Segundo, CA) recently opened its 4,000 ft.2 cleanroom in Holly Springs, MS for HEPA, ULPA and MEGA filter production.
Paint Spray Working Group Formed
According to Rob Nightingale, president, Cleanroom Garments (Downsview, Ontario) “the paint-spray industry is huge,” with users running the gamut from materials suppliers, to small parts, to large automotive and aerospace assembly facilities. Cleanroom Garments, itself, has a Class 1,000 facility that handles strictly automotive paint-spray processing garments, boots, gloves and wipers.
By Nightingale`s estimates, the automotive segment is not just the “big three” and Japanese companies, but multiple tiers of controlled facilities numbering at least in the hundreds, “and these tier-one suppliers will easily have 100+ employees in the cleanroom.” Nightingale is also vice chair of the Institute of Environmental Sciences (IES) Contamination Control Working Group for Paint Spray Applications (WG29). The goal of WG29 is to issue a set of nonmandatory Recommended Practices (RPs) and guidelines for controlled paint spray environments, including, but not limited to, the automotive and aerospace industries. The group just completed its second meeting in November of 1994, and expects to have a completed draft ready for the annual IES meetings in May with a final version this November.
According to the group`s chairman, Chuck Berndt of C.W. Berndt Associates (Highland Park, IL), “we started the group because it`s time to stop re-inventing the wheel, get a cross-polinization of ideas and experience going, and get some of these guys out of the Mesozoic era.” Berndt believes, WG29 may well lead to other IES subcommittees and RPs over the next five to 10 years.
“Raising awareness is the first step, and not just in the paint spray arena. The use of contamination control in food processing can reduce or eliminate the need for preservatives and extend shelf life, all of which goes straight to the bottom line. Why are these practices in much more common use elsewhere, especially Japan?,” asks Berndt. Adds Nightingale, “there are so many different avenues for cleanrooms now. We need to reach out and forge new bonds and point out the commonalties and benefits between end-users.”
WG29 is encouraging membership, active participation and suggestions. Contact IES Headquarters (Mount Prospect, IL) (708) 255-1561. n