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Clean and green: understanding the environmental challenges of solvents PDF Print E-mail
Tuesday, 30 June 2009 00:00

Mark Nursall, technical sales specialist, 3M United Kingdom tells Finishing about the environment pressures that companies are under

Never before have clean-rooms – and indeed, industrial and manufacturing environments in general – been under such pressure to take a more environmentally-responsible approach to the products being used.  Of course, this is all to the good, because we all need to be more aware of the potential damage that certain chemicals can cause.  However,  it has meant that managers of clean-rooms are having to build a clear  understanding of what is – and is not -  permissible, both now and in the near future, particularly with the advent of several pieces of legislation that cannot be ignored.  The good news is that while the volume and range of legislation and rules can be confusing, there are some clear and very attainable options for end users.

Update on the SED
Perhaps the most widely known piece of legislation in this area is the European Union Solvents Emission Directive (SED), which became mandatory on 31 October 2007.  However, despite the fact that it has been widely publicised for several years, it is concerning that there are many companies not yet complying with this legislation.  Perhaps this is not surprising, given that the legislation is not a cut-and-dried  ‘yes/no’ situation.

For many readers, the SED will need little introduction, but here is a brief reminder of its scope: the new directive places restrictions on the “loss of solvent to atmosphere”, especially solvents that are classified as having ‘CMR’ potential.  CMR stands for ‘carcinogenic, mutagenic or toxic to reproduction’.  Popular solvents classed as CMRs include the trichloroethylene (more commonly known as Trike) and n-Propyl Bromide (nPB), both of which are commonly used in cleaning.

The SED does not insist on an outright ban of these substances but places more stringent restrictions on solvents carrying the Health & Safety Executive’s ‘Risk Phases’ defined in the directive.  CMR solvents are exempt from SED regulation for usage of less than one tonne per year. This may sound straightforward, but for many companies, it can be hard to predict the quantity of solvents that will be used, and in many applications, annual usage will exceed one tonne.

This is why a growing number of firms are looking at another alternative: namely, to use cleaning fluids that do not fall foul of the SED’s CMR restrictions. Of course, water is one route, but on its own it is not always a particularly efficient cleaner and still results in contaminated waste fluid requiring safe disposal.  Instead, companies are adopting hydro-fluoro ethers (HFEs) as alternatives to CMR-classified solvents.  Available from a number of suppliers, HFEs are rated as being ‘non ozone depleting’ and have comparatively low toxicity.

In the past few years, the development of HFEs has been intense, with widely available commercial products that offer excellent performance compared to more traditional cleaning fluids.   Available in drums and aerosols, HFEs often offer lower cost of ownership than traditional cleaning chemicals partly due to using less fluid, which helps to reduce overall cost in the long-term.
Despite this, in my experience there are still a large number of users who seem to be dragging their heels on SED compliance.  Many are at the stage of still looking at alternatives, with requests put out to suppliers, all of which buys everyone some time.   In reality, does it matter if a company has not complied with the SED yet?  I believe that there indications that the authorities responsible for enforcing environmental legislation in general – the Health and Safety Executive, DEFRA and local authorities - are likely to start clamping down on companies who have failed to put adequate plans in place.  Companies should not under-estimate the force of the SED.

The banning of HCFCs
As far as clean-rooms are concerned, there are other pieces of legislation of which to be aware, including the phasing out of HCFC-141B on 31 December 2008.  A result of the Montreal Protocol, this is an EU-wide ban. Categorised as an ozone-depleting fluid, this is a commonly used solvent used for cleaning in aerospace cleanroom applications.  For companies who have not already got replacement plans in place, there is not much time left to devise a strategy, approach suppliers and test the performance of available products.

Again, HFEs are being viewed as an alternative, since being non-ozone depleting, they are outside the scope of the ban.  For cleanroom applications, they are likely to be used as part of a co-solvent process, using an HFE rinsing agent and a solvating agent, to ensure a thorough clean but without risking damage to delicate parts, such as circuit board components.  One of the concerns about using other solvents , such as water or HFCs has been that they leave a white residue or even cause corrosion.  This is not the case with HFEs, so it makes sense to include these criteria in testing procedures when evaluating cleaning processes.

F-Gas Regulations
Another piece of legislation looming on the horizon is the F-Gas Regulations No 842/2006, which comes into effect on 4 July 2008.   Strictly speaking, these relate mainly to air-conditioning and refrigeration fluids, but in reality, have an impact on the use of HFC solvents used in clean-rooms and other environments.

The objective of the regulations is to reduce the emission of fluorinated greenhouse gasses.   What is only now becoming clear is the activities that users will have to put in place to address the legislation.

Fortunately, companies do have some time to sort out their plans.  4 July 2008 is the date from which companies must start to establish a strategy and put in place processes for training and certification to the specified standards.  Exactly one year later, on 4 July 2009, companies will not be allowed to take delivery of greenhouse gasses affected by the Regulations unless they have certified operators in place.  Suppliers will also need to ensure that products are labelled clearly as greenhouse gasses.
HFC-4310mee and HFC-365 – both of which are used in commonly used commercial products – are specifically listed in Annex 1 of the regulations.  Once more, HFEs escape the legislation, because they are classed as having much lower global warming potential.   To put this into perspective,  according to figures from the Intergovernmental Panel on Climate Change (IPCC), HFE-7100, a solvent developed by 3M, has 280 GWP (Global Warming Potential) compared to 1500 for HFC-4310mee, as stated in the F-Gas Regulations.

 Therefore, companies wishing to bypass the whole process of needing to measure greenhouse gas consumption and organise certified staff, HFEs provide an alternative.  So, there are already three pieces of legislation of which companies need to be aware.  These join the established Restriction of Hazardous Substances (RoHS), mandatory since 2006, and the introduction of REACH – the Registration, Evaluation, Authorisation and Restriction of Chemicals – which has more impact on  producers than end users, but of course, users should check the REACH status of their suppliers.

The future is green
Is this the end?  Unlikely.  Once we begin to delve further into the impact of materials and fluids in manufacturing processes, there are likely to be other areas where legislation or limitations will be introduced.  This is why it makes sense for companies to start looking at the bigger picture and to begin adoption of chemicals and processes that not only adhere to current legislation, but are likely to be acceptable in years to come.  So far, HFEs have a clean track record.

Of course, switching to alternatives takes time and money.  Companies may have to carry out considerable research and testing, which can be difficult to balance against the daily priorities of running a profitable business.  However, for companies that have corporate responsibility and environmental strategies in place, it is in their interests to embrace the spirit of the legislation, which after all, is about protecting  employees as well as the planet.   Plus, while adherence to legislation may not be straightforward or quick, at least there are some clear options open to users, particularly the use of HFEs.  While these may not be the solution for every situation, they certainly provide many cleanrooms  with a commercially viable and attainable alternative.

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