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This is an example of a vapor degreaser with a basket of aluminum fluid dispenser nozzle assemblies, boiling solvent, and vapor cooling coils. The cleaning process for manufactured device components is extremely important to the overall quality of device production. This is especially true in the medical industry, which requires a strict level of sterility and cleanliness to ensure the product’s safety and performance for patient care.

The ease of use, combined with their highly effective cleaning performance, vapor degreasing systems had long been a preferred method of cleaning. However, about 15 years ago, a shift took place in cleaning process device engineers and manufacturers preferred to use when cleaning devices and components. Environmental concerns fueled an industry wide trend to switch from vapor degreasing systems, which at that time used chemicals harmful to the ozone, to aqueous (water) based systems. Although there were advantages to using the aqueous systems, the environmental concerns at that time outweighed many of the benefits of vapor degreasing systems.

Today, however, vapor degreasing cleaning systems are seeing renewed interest with manufacturers and engineers because of advances in solvent technology that are leading to environmentally friendly options – combined with an awareness of downfalls in aqueous cleaning systems. In fact, though it may seem surprising, many manufacturers and engineers are discovering that a properly designed and maintained vapor degreaser can be more environmentally friendly than an aqueous-based cleaning system of similar capacity. Not only can they be environmentally-friendly, they remain the most effective, and at an overall lower cost option.
 

A Primer
The vapor degreasing system is engineering simplicity at work. It essentially consists of a top-loading steel vessel composed of two chambers, both filled with solvent. In one chamber, the solvent is heated to a boil, which then generates a vapor cloud that rises to meet two sets of cooling coils. These coils cause the vapors to condense and return to their liquid state. This liquid is then channeled back to the second chamber, the rinse chamber. This closed-loop system has few moving parts and ensures that the solvent is reliably clean for ongoing cleaning needs.

A hoist lowers a basket containing the dirty parts through the vapors and into the boil sump first. After being raised back up, the basket is lowered into the rinse sump. The rinse sump always contains the clean solvent that has been condensed from the vapors. The use of ultrasonics in this rinse sump further ensures residue-free, clean parts. This process is easily programmable and allows for excellent process control and repeatability. The parts then come out clean, dry, and immediately ready for packaging or further processing. In comparison to aqueous systems, the advantages of the vapor degreasing system are clear: they are very easy to use, efficient, smaller in design, and lower in overall capital and operating costs.
 

Effective
For designers and manufacturers, the low viscosity and surface tension ratings of solvents, combined with their volatility, allow them to clean very effectively, even in small crevices and areas that water in aqueous systems cannot easily penetrate. For medical device designers, this means they are not limited in product design because of cleaning limitations with aqueous systems. They can be sure that all surfaces of the finished product will be effectively cleaned and safe for the patient.

Solvents dry fast and completely, leaving no moisture or residue on parts after they exit the vapor degreaser. Solvents are inherently hostile to the growth of bacteria, and offer an easy way to engineer bioburden issues out of the manufacturing process. This is a significant difference from water-based cleaning systems, especially when components or finished devices are packaged immediately after cleaning. Even trace amounts of moisture can allow the growth of bacteria and create related bioburden issues, compromising the performance and appearance of the device and requiring re-cleaning of the device or disposal of it altogether. With aqueous systems, the rinsing and drying process is much more complex; blowers or heated dryers are often used to reach nooks and crannies, and even then, spotting or corrosion of parts can be a problem if any steps in that process are missed.

Vapor degreasers offer a simple process that is more chemically effective at removing contaminants than aqueous systems, which means that they do not require additional mechanical action or increased temperatures to be effective. The typical aqueous setup  will have complex ultrasonic or high pressure spray systems or agitation systems in addition to heaters to raise 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.
 

Environmentally Friendly
As mentioned, about 15 years ago, environmental concerns, and new regulations led to a shift away from solvent-based vapor degreasing cleaning systems toward aqueous systems. Solvents were still effective for all the reasons above, and there was no question about that; however, at that time they also contained chlorofluorocarbons (CFCs) which were found to contribute to ozone depletion and became banned across industries. Manufacturers turned to aqueous systems to meet those environmental requirements.

Intuitively, water seems like it would be the more environmentally friendly option. However, there are a number of reasons why the advantages are not so clear.

Today’s solvents meet strict Environmental Protection Agency (EPA) standards. Although some solvents are a regulated waste and require special disposal under EPA requirements, this is actually comparable to aqueous system requirements. In fact, aqueous cleaning systems generate a waste water stream that requires treatment before discharge. Many aqueous detergents contain non-biodegradable ingredients, which can make discharge to sewer systems or surface waters problematic. For example, some cleaners are biodegradable when new, but are no longer biodegradable once used.

Water used in aqueous systems does not come straight from the tap. Water virtually always needs to be pre-treated in some way to be viable for use as a cleaning agent. This is necessary to ensure there are no trace materials or minerals that would compromise the effectiveness of the process. In contrast, solvents come ready-to-use and require no mixing.

If we look beyond the actual cleaning agent (water vs. solvent) to assess the overall sustainability of a manufacturing process – vapor degreasers have significant advantages to consider. The energy required to operate a vapor degreasing system is lower than the energy required for an aqueous system. Aqueous systems require high temperatures to be effective, while solvents have lower boiling points and therefore use less heat energy. Drying parts after aqueous cleaning requires an additional step in the process, while parts exiting a solvent-based vapor degreasing system come out dry. This lowers the required energy use in the facility.

Aqueous cleaning processes operate horizontally and contain many moving parts, which means the machines and overall systems have a larger footprint, requiring more overall space in a facility and therefore also requiring more electricity and consumption of energy. Vapor degreasing systems, on the other hand, work vertically, taking up little space in a facility and requiring less energy than aqueous systems. This is not only an environmental benefit – it is also a cost benefit for a manufacturer who is leasing space and paying the utility bills.
 

Lower Cost
As described in the previous paragraph, many of the overall effectiveness and environmental benefits of vapor degreasing systems turn out to have cost benefits for the manufacturer.

The initial effort required to correctly design, test, and install an aqueous-cleaning system is much greater than that for a vapor degreasing system. This is due to the increased complexity of the aqueous cleaning process and the increased reliance on equipment as opposed to the cleaning solution. This limitation is very significant for manufacturers that are very short on time, and can increase the overall cost of the process.

Aqueous systems typically require a larger footprint in the manufacturing facility. This not only requires more space, it also requires more supervision to ensure effectiveness. Vapor degreasing systems are low maintenance and include programmable process controls and hoists that require very little oversight for operation. Essentially, once programmed, a computer can take over the operating process. Often a manufacturing engineer needs to ensure the aqueous process’s chemistry is on target or adjustments need to be made. A solvent vapor degreaser’s chemistry is consistent and requires little attention. The savings on labor costs provided by vapor degreasing systems can be significant compared to aqueous systems.

While the up-front cost for solvents appears to be more expensive than water, which is free, a closer look shows that this is not the case. As mentioned, water virtually always needs to be treated in some way to be viable for use as a cleaning agent. The costs associated with treating the water and then also disposing of the dirty water after cleaning can add up. When coupled with the higher supervision needs and increased facility footprint, the cost benefits of free water may not be as impactful.

Finally, bioburden, which forms when devices are packaged with residual moisture, is a problem with aqueous systems, but not with solvent-based systems. For a manufacturer that has used an aqueous system and has had to re-clean, re-package, or scrap devices that have been affected by bioburden, the vapor degreaser system can offer significant savings in time and money. It can also ensure that patients and doctors who receive products down the line are completely satisfied.
 

What it means
The bottom line? Designers and manufacturers who desire an effective, low cost cleaning option should consider using a solvent vapor degreasing process. With new advances in solvent technology, and the increasing awareness of aqueous system drawbacks, a solvent vapor degreasing process may not only be the most cost-effective solution but also the most environmentally sound option.
 

MicroCare Medical Inc.
New Britain, CT
microcare.com