Mike Jones, from cleaning specialist MicroCare, makes the case for vapour degreasing as the most efficient way to clean medical components and eliminate bioburden risk.

As medical components become smaller and more intricate it can be challenging to find an effective cleaning method that works consistently. Contamination varies widely and can range from general handling soils to inorganic contamination from manufacturing and insoluble particulates from a machining process. All of these can have serious implications on the end-product including the risk of bioburden. The processes used in the development and manufacture of medical components has no room for error.

Since nearly all devices require some measure of cleaning during manufacturing, the challenge is to specify a cleaning process that is (a) suitable for a variety of materials including delicate plastic injection-moulded parts, stainless-steel microtubing, or complex mechanical assemblies, (b) reliable and consistent, and (c) affordable and safe. It’s a complex decision.

One of the most effective critical cleaning methods is vapour degreasing. This process makes it easy to clean small components with complex geometries. The process also successfully satisfies the performance requirements needed within the medical device industry and the regulatory regimes in different countries. Recent advances in solvent technology have generated environmentally progressive, low-temperature cleaning options that greatly minimise the bioburden and economic issues.

A simple process

Vapour degreasing is a relatively simple machine and a very simple thermodynamic process. Typically, the systems consist of two chambers filled with a nonflammable solvent. The “boil sump” heats the solvent to a low-temperature boil (typically around 40˚C) which generates a vapour cloud (“steam”) that rises upwards in the machine. As the vapours rise, they contact cooling coils which are arrayed around the inner walls of the machine. The cooling coils condense the vapours back to their liquid state.

This distilled solvent then is directed back to the “rinse sump” where the parts are rinsed as the final step in the cleaning process. When filled with solvent, the rinse sump overflows back into the boil sump to complete the recycling loop. This closed-loop system has few moving parts and ensures that the solvent is reliably clean for ongoing cleaning needs.

Cleaning is fast and easy with a vapour degreaser. A basket containing the contaminated components is lowered through the vapours and into the boil sump for their first cleaning. After a few minutes, the parts then are moved into the rinse sump. The rinse sump always contains pure, clean solvent that has been distilled from the solvent vapours so rinsing is highly effective. Ultrasonics in the rinse sump can further ensure residue-free parts. This process is easily programmable and allows for excellent process control and repeatability. Components come out clean, dry, at room temperature and immediately ready for packaging or further processing.

The benefits of using a vapour degreaser are clear. It delivers very high levels of cleanliness to ensure patient safety and product performance. It also is a safe, environmentally-friendly and affordable process. The systems are small, use little electricity and never use any water. A well-engineered solvent cleaning system is easy to validate and will simplify device sterilisation by removing sources of bioburden from the finished products.

Remove the Bioburden Risk

Bioburden can be a huge issue within the cleaning process, especially if the cleaning method uses aqueous technologies. Using aqueous-based cleaning systems not only instigates a bioburden risk, but it also generates a waste water stream that requires expensive treatment. Higher temperatures also are required for effective cleaning, which means more energy is used which can have a significant effect only on the environment and also on the pocketbook.

There are many conditions that can cause bioburden, but water is a primary growth medium for bacteria. Even trace amounts of moisture in hard-to-reach locations can encourage the growth of bacteria, compromising the ability to properly sterilise the device. Therefore, it is important to remove water from the cleaning process to minimise this threat. If it is not properly addressed it can result in increased complications during the validation of the product.

A solvent-based cleaning process is a nonpyrogenic environment. This feature alone significantly reduces the risk of bioburden. Solvents dry very quickly and completely leaving no residues on parts after they exit the vapour degreaser. Solvents also do not require additional mechanical action (high pressure sprays or air knives) or increased temperatures to be effective. The process offers an easy way for engineers to validate bioburden issues out of the manufacturing process. Lastly, solvent cleaning has very high throughput because the cleaning is fast and the finished devices are ready for processing immediately after cleaning.

The low viscosity and surface tension ratings of solvents, combined with their volatility, allow them to clean very effectively, even in small gaps and areas that water in aqueous systems cannot easily penetrate. Medical device manufacturers can be sure that all surfaces of the finished product will be effectively cleaned and safe for the patient.

As medical devices are evolving into more compact and complex components, cleaning becomes more and more difficult. Perfecting and validating a cleaning method that works effectively on the intricate parts of medical components is vital to ensure patient safety. Vapour degreasing offers a simple, proven and reliable answer to cleaning processes within the medical manufacturing industry.