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Emissions directive - know your options
Monday, 09 July 2007 16:24

Richard Starkey, SAFECHEM Representative UK says that the European Solvent Emissions Directive (SED) will have big implications for UK Finishing companies

On the 31 October 2007, the European Solvent Emissions Directive (SED) will come into full force. The implications are vast, because the Directive will affect all surface cleaning installations that consume more than two tons of any volatile organic solvent per year, or more than one ton of any solvent classified as a CMR and carrying the risk phrase R40, R45, R46, R49, R60 or R61, such as Trichloroethylene (TRI) and N-PropylBromide (nPB).  Yet while the Directive sets limits on solvent emissions, it does not limit their use or dictate the method of emission reduction. This inherent flexibility allows solvent users to choose the best emission reduction method for their particular circumstances. Making that choice, however, depends on a solid understanding of the compliant options.

SED basics

Activities above the SED solvent consumption threshold will need to meet emission limits in waste gases and a fugitive emission limit value, or implement a solvent reduction scheme. Stricter requirements will apply for users of solvents classified as category 1 and 2 CMR – such as TRI and nPB – who will need to consider substitution with lower-risk alternatives.

What is important to note, however, is that TRI is not banned. If use of the alternative leads to an unacceptable loss of quality or an unacceptable increase in total costs, the Directive allows for continued use of TRI, but only under proper handling conditions, i.e. closed cleaning equipment connected to a closed-loop delivery and take-back system.

Compliant options

Because of users’ diverse cleaning requirements, there is no single SED-compliant solution. A user will need to evaluate a prospective solution’s fitness for use, its potential effects on the environment and human health, occupational exposure, economic consequences, and, of course, specific cleaning requirements. 

Solvents

Chlorinated solvents remain in most cases, the most powerful, effective and efficient solution for high-quality cleaning. Fortunately, significant opportunities to reduce emissions, exposure and consumption exist. A closed-loop delivery and take-back system in conjunction with closed equipment provides a highly effective, safe and compliant solution. In some cases, solvent consumption can be reduced below the threshold and further abatement may not be necessary.

Modified alcohols also demonstrate high cleaning performance and can act as an alternative to chlorinated solvents, depending on the cleaning quality required. Because of their high-polarity, they are excellent for particle removal. They can be used efficiently in closed-loop systems.

Hydrocarbon solvents can be an option for degreasing purposes. Given their high flammability, proper risk control measures are necessary.

Alternative cleaning processes

Aqueous cleaning can be a viable alternative cleaning process as long as the cleaned parts can remain wet.  Solvent cleaning typically offers greater flexibility and convenience, because aqueous cleaning separates the cleaning, rinsing and drying stages. The drying stage, in particular, presents special challenges. Not only does it demand ample plant space, it also consumes far more energy, which has an adverse environmental effect by increasing global warming.  When drying is unnecessary and quality less of an issue, though, aqueous cleaning is a good option.

Finding the right solution for SED compliance

Whether you are looking into continued solvent cleaning or an alternative cleaning process, the starting point for evaluation should always be your specific situation. Consider using the following check-list to guide your thinking:

• Will we be able to maintain quality levels?

• By how much will our emissions be reduced? Will we comply?

• By how much will our solvent  consumption be reduced?

• Will more energy be consumed?

• Will my running costs be reduced?

• What floor space is available?

• How will we protect our employees from exposure?

• What are the risks involved, and how will we properly manage them?

• What further regulations apply?

Be sure to review all of the options, stay abreast of developments, and seek expert advice from your solvent or equipment supplier. With a thorough assessment of your options, you will be able to achieve SED compliance in a way that works best for your specific needs.