Solvent vs. Aqueous Cleaning

What is a solvent cleaning solution?

Solvent-based cleaners refer to solutions utilising non-halogenated solvents, such as modified alcohols or hydrocarbons. Alternatively, halogenated solvents can be utilised such as perchloroethylene or fluorinated solvents. These fluorinated solvents can be a singular solvent solution or a mixture of multiple liquids, agents or compounds forming a cleaning solution. Solvent machines use the natural degreasing power of the solvent to dissolve dirt and/or grease from components.

What is an aqueous cleaning solution?

Aqueous cleaners, also known as water-based cleaners, refer to solutions that make use of builders (amines, phosphates, Hydroxides/Acids) as their primary constituent alongside other compounds such as wetting agents, detergents, de-emulsifiers, inhibitors, anti-hardness optimiser, defoamer, biocides & fragrances.

Comparing solvent cleaning vs aqueous cleaning

To help you make an informed choice, knowledge of how both solvent and aqueous cleaning works is required. Here, an in-depth analysis of solvent cleaning vs aqueous cleaning solutions are provided using specified criteria:

1.      Biodegradability

This criterion refers to the capability of a cleaning solution to be decomposed into less harmful biodegradable components that can be easily disposed of.

In terms of biodegradability, solvent-based cleaning solutions are generally classified as biodegradable. This means the combination of compounds that make up a solvent-based solution are often degradable into individual elements or compounds depending on the configuration of the cleaning solution. Aqueous cleaning solutions can also be classified as biodegradable.  However, some “stronger” solutions are not as Biodegradable as they may contain chemicals such as biocides, complexing agents, dyes and surfactants (which reduce surface tension). These components can make them harmful to the environment if used in very high concentrations.

2.      Eco-friendliness

The eco-friendly ratio of a cleaning solution builds on its biodegradability. This focuses on a solution’s recyclability and impact on the environment.

The eco-friendly index takes into consideration multiple factors that include the packaging of a product, the chemicals it uses, energy utilisation rate when used with cleaning machines, and water consumption rate. These factors come together to determine how compatible a solvent is with recycling and its impact on the environment.

Solvent-based cleaning solutions are typically biodegradable. Some have high evaporative properties, which offer excellent drying behaviour and penetration characteristics. When using these solvents, the need for drying cleaned parts is generally not required due to the drying characteristic associated with the solution. However, these are typically chlorinated solvents which are less environmentally friendly.  The use of closed-machine technology where the system operates under vacuum helps for those solvents with high boiling points.  The closed-machine technology will also reduce spillage, waste and emission rates when utilising solvent-based cleaning solutions.

Like solvent systems, water-based cleaning solutions require elevated temperatures for the cleaning process.  This aids the drying process, but often a dryer is required to fully dry cleaned components.  

3.      Working mechanism

This criterion focuses on the working process the solution employs to clean a component.

Comparing cleaning mechanisms for solvent cleaning vs aqueous cleaning solutions reveals important differences. Solvent-based solutions employ a dissolution process whereby chemicals dissolve and distil oils, grease, dirt and other foreign components from a surface or equipment. Water-based cleaning solutions employ emulsification and encapsulation to clean surfaces.

Both solvent and water-based cleaning solutions may require multiple stages and the application of drying finishes off the cleaning process. In some scenarios, a requirement for the cleaning process is that the detergent integrated into a water-based solution must match the contaminant and the type of metal that requires cleaning.

Solvent-based cleaning solutions can be a more universal option if a variety of oils needs to be removed.  However, water-based solutions are more flexible when considering particulate removal.

4.      The total cost of ownership (TCO)

The operating cost, usage process, labour cost during use, alongside the cost of purchasing a solution, are factors to consider when totalling the cost of owning a solvent.

The earlier analyses of solvent cleaning vs aqueous cleaning paint a picture of the total cost of owning and using a solvent-based solution or its water-based alternative. Energy consumption is defined by the process temperature, the number of cleaning stages and drying requirement involved, but typically the running costs are comparable.

In terms of the base cost for both options, the cost of purchasing a solvent-based cleaning solution is typically higher than that of a water-based cleaning solution.

Therefore, the total cost of ownership, which is determined by factors such as capital investment, energy consumption and consumable running costs, will depend very much on the cleaning application.  Only after all these factors are fully evaluated can you define which cleaning method has a lower cost of ownership.

5.  Media monitoring

The preparation process of the solution is also an important factor to consider when choosing a cleaning solution. With solvent cleaning, there is little addition of chemicals required, except for stabilisers which are only added if necessary. Additionally, solvent bath monitoring is generally conducted once a week in 20 minutes or less. Water-based cleaning, on the other hand, requires a little more regular monitoring depending on the complexity of the process; tests may be required weekly.

Conclusion

As stated, choosing between solvent cleaning vs aqueous cleaning solution is dependent on your particular cleaning requirements. The right fit must address your environmental, utilisation and financial requirements. The make-up or structure of your cleaning apparatus, the equipment to be cleaned, and the industrial layout are also considerations that must be taken into account when choosing the best cleaning solution for your industrial facility. Reach out to a Turbex representative for your cleaning solution needs.