Reach for alternative to trichloroethylene

The aim is to replace TRI-containing solvents with alternative cleaning media or processes. If this is not feasible, after 21 April 2016 the use of TRI will only be permitted under an exception permit in state-of-the-art closed systems.

Trichloroethylene is used specifically in the precision-cleaning of parts in industries such as aircraft or medical equipment. The solvent was registered with the European Chemicals Agency (ECHA) under the provisions of the European REACH (Registration, Evaluation and Authorization of Chemicals) legislation.

Given the submitted data regarding hazards, uses, exposure and risks, TRI was classified as a substance of very high concern (SVHC) and included in Annex XIV to the REACH regulation. It follows that any further use of this solvent will, on principle, be impossible in all EU member states and in the European Economic Area (EEA) after the so-called 'sunset date' of April 21, 2016. Users must replace TRI with another suitable cleaning medium or process. If a substitution is not feasible for technical or economic reasons, the user must apply to ECHA for an authorisation. This application must be filed by October 21, 2014. 

Alternatives

Dürr Ecoclean has a portfolio of solutions for alternative cleaning media and can provide independent advice across technology platforms. Close cooperation with solvent producers and manufacturers of water-based cleaning media ensures that the result will match the cleaning task in an optimum manner. The main criteria consist in the type and amount of contamination, the material and geometry of the part to be cleaned, and the required degree of cleanliness. 

Compatibility between the contaminant(s) and the cleaning medium also plays a key role. It is mainly a function of the polarity of the respective substances – a parameter which indicates how electric charges are distributed within a molecule and how its electrostatic forces act on the outside. These factors influence a substance's solubility or, more particularly, its ability to work as a solvent. The primary rule here is that 'like dissolves like'. Accordingly, non-polar substances such as fats and oils are readily soluble in non-polar solvents but poorly soluble in polar ones. Conversely, polar substances such as salts or emulsions are readily soluble in polar media (water) but poorly soluble in the non-polar type.

Based on this chemical principle, a preliminary selection may be made from among the following media: perchloroethylene, non-halogenated hydrocarbons, polar solvents, or water-based cleaning media. The most suitable alternative to TRI can be determined through cleaning trials with real contaminated parts. Dürr Ecoclean conducts such trials free of charge at its own test centres in various European countries. Tests provide the opportunity at the same time to determine the necessary process parameters and process technology, so that the specified cleaning result will be achieved with due technical reliability, repeatability and efficiency under real-life production conditions. 

Authorisation of TRI

Exemptions from the substitution requirement are possible only in applications where, for technical or economic reasons, TRI cannot be replaced by the sunset date, or not at all. In the request for authorisation, extensive evidence of the substitution efforts undertaken must be presented. For instance, the applicant is required to submit the results of cleaning tests demonstrating that the necessary cleaning quality is not achievable with an alternative solvent. An important technical reason may also lie in the fact that temperature-sensitive products bar the use of solvents with a higher boiling point. 

An important economic reason for an exemption might be that the customer's cleaning process has undergone third-party certification, typically at a great cost and effort, and its re-certification with a different solvent would be economically unreasonable. Moreover, the request for authorisation must include detailed information on the cleaning task and on TRI use and handling practices. It must further be demonstrated that the risk associated with the use of this solvent is controlled in an adequate manner. 

Irrespective of the above factors, an authorisation will be granted only on the condition that the continued use of TRI takes place in a closed cleaning system conforming to the most recent state of technology. This requirement is met, for example, by all Dürr Ecoclean equipment developed for cleaning with chlorinated hydrocarbons.