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Tighter cleanliness standards and increasingly complex part designs (such as those demonstrated in this surgical stapler) are leading medical manufacturing companies back to solvent-based cleaning.
Vapor degreasing systems have few moving parts and operate vertically, requiring less floor space and less energy than aqueous systems.
Tighter cleanliness standards have forced an increased awareness of problems stemming from residue that is sometimes left behind on medical devices after the manufacturing process. In many cases, the FDA now requires manufacturers to provide validation documentation verifying how parts are cleaned and if contaminants remain on the devices after cleaning.
An Industry-Wide Shift
Vapor degreasing recently has emerged as a cleaning trend in the medical device industry, however, it is not at all unfamiliar to device engineers and manufacturers. Until about 15 years ago, vapor degreasing systems had long been a preferred method of cleaning because of their simple design and highly effective cleaning performance. But as environmental concerns arose over the properties of some solvents used in the systems, aqueous-based systems became the preferred cleaning process. The medical device industry shifted from easy-to-use, solvent-based vapor degreasing systems to more complex, water-based systems on the promise of lower costs and environmental compliance. Today, however, the shift seems to be back in the opposite direction.
The cleanliness of any manufactured component is important to the overall quality of the finished product, especially in the medical device industry, where a strict level of sterility and cleanliness is required and helps ensure the product’s safety and performance in patient care. Furthermore, for optimal coating or packaging of the device – which is often the final step in the manufacturing process – a clean part is essential. This, coupled with more stringent Food and Drug Administration cleaning requirements, makes a shift back to using solvent-based cleaning systems no surprise.
Why Vapor Degreasing vs. Aqueous Cleaning?
When the industry moved away from vapor degreasers about 15 years ago, many of the solvents, while extremely effective in cleaning, contained chlorofluorocarbons (CFCs), which contributed to depletion of Earth’s ozone layer and were banned across industries. Manufacturers turned to aqueous systems to meet environmental requirements.
Since then, advances in both machine and solvent technologies have led to the availability of more environmentally friendly options in vapor degreasing. Many manufacturers and engineers are discovering that a modern, properly optimized vapor degreaser actually can be more environmentally friendly than an aqueous-based cleaning system of similar capacity.
Although water seems like it would be the more environmentally friendly and lower-cost option, it is not that simple. Today’s solvents meet strict Environmental Protection Agency standards, and their disposal requirements are actually comparable to those of water in aqueous systems. Aqueous systems do not use water that comes straight from the tap; the water virtually always needs to be pretreated in some way to be viable for use as a cleaning agent and then treated again prior to disposal. These treatment processes add expense to aqueous cleaning. Many local governments also are regulating the industrial use of water because of supply issues.
Another less obvious, but increasingly important, impact on the environment is the energy required to operate these cleaning systems. Cleaning solvents have lower boiling points, so vapor degreasing systems do not require temperatures to be as high as in aqueous-based systems for effective cleaning and drying, and therefore require less energy to operate. Aqueous cleaning systems also use additional energy to dry the parts after cleaning, while parts exiting a vapor degreasing system come out dry and ready to use.
Finally, aqueous cleaning processes operate horizontally and contain more moving parts than vapor degreasing systems, which means the machines and overall systems are more complex, require more overall floor space and consume more energy. Lower utility bills and possibly even less cost associated with leasing space means a cost-savings benefit in addition to the environmental benefits.
More Effective Cleaning
Low viscosity and surface tension ratings of solvents, combined with their volatility, enable them to clean very effectively, even in small crevices and areas that water in aqueous systems cannot easily penetrate. This makes the vapor degreasing process suitable for almost any part geometry and easy to validate. Medical device designers do not need to feel limited in their product designs knowing that all surfaces of the finished product, regardless of geometry, will be effectively cleaned and, thus, safe for the patient.
Vapor degreasing is a simple process that’s more effective in removing contaminants than aqueous systems, and additional mechanical action or increased temperatures typically are not required. The typical aqueous setup includes complex ultrasonic or high-pressure spray or agitation systems in addition to heaters to raise the temperatures of the detergent baths. When dealing with thick or insoluble contaminants, or delicate parts such as those in medical devices, the usefulness of an aqueous system can be significantly limited.
A lubricious coating often is applied to manufactured medical device components to address the challenge of stacked tolerances in mechanical assemblies, and to reduce friction and the forces needed to actuate certain devices, such as surgical staplers. If there is residue left on the part after cleaning, this coating will not adhere properly, and operating issues can arise once the device reaches its end-user.
Bioburden are contaminating microbes that forms when devices are packaged with residual moisture, and this also is a potential problem with aqueous systems that requires constant vigilance. Solvent-based systems typically do not encounter bioburden problems because, unlike water, solvents are inherently hostile to the growth of bacteria. The fact that parts come out of the vapor degreasing system dry and immediately ready for packaging further deters the formation of bioburden.
Water-based cleaning systems require a more complex rinsing and drying process, with blowers or heated dryers often used to reach nooks and crannies. Even with this drying equipment, spotting or corrosion of parts can be a problem if any steps in that process are improperly timed or missed. Even trace amounts of moisture can create related bioburden issues, thus compromising the performance and appearance of the device. These issues are especially common when components or finished devices are packaged immediately after aqueous cleaning.
Devices that are affected by bioburden must be recleaned, repackaged or even completely scrapped, requiring extra time and money. Not having to worry about bioburden can also help ensure that patients and doctors who receive products down the line are completely satisfied.
Addressing Specific Needs
No one cleaning system is right for everyone. Vendors can help review the cleaning needs of an individual company and determine what cleaning system and solvent fit best. What is true across the board is that when cleaning medical devices and parts, it is especially important for designers and manufacturers to find a cleaning solution that does not leave a residue, meets EPA regulations, is easy to validate, offers reduced risk of bioburden formation and has excellent materials compatibility. These significant factors should be considered when making a long-term investment in a cleaning process. With new advances in solvent technology, the most cost-effective, environmentally sound option just may be an old favorite.
Jay Tourigny is senior vice president at MicroCare Medical, a supplier of advanced cleaners, carrier additives, coatings and lubricants to medical device designers and manufacturers in North America and Western Europe. Learn more by calling 860-827-062 or visiting microcaremedical.com.
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