Should you switch? Barry Eaton of SAFECHEM Europe asks whether you should be changing your cleaning methods.
Actually, if you consider changing the cleaning agent, there are three fundamentals that are not negotiable: safety, environmental impact and performance. If your option of choice fits with those criteria it's likely that you end up with a cost effective solution too.
The substance attracting a lot of attention currently is trichloroethylene. At least if one looks at the strap line on adverts. For example "Is Trichloroethylene causing you a headache?", "Why use XXX to replace trichloroethylene?" or "A cost effective alternative to Trike for vapour degreasing". The options referred to in those adverts cover a range of types; an aqueous solution, a non chlorinated solvent, an alternative chlorinated solvent. Even the alternatives can't decide which way to go!
Of course anyone using a carcinogen should consider options. The law asks you to. And, if not (remember that Article 7 of the Solvent Emissions Directive gives four specific reasons why you can carry on using these materials if alternatives have been considered), consideration must be made of how the use of Trike can be carried on most effectively and safely. This is what both the Solvents Emissions Directive and the "Voluntary Industry Commitment" (which closes the gap that the 1 MT derogation offers) address. With regard to REACH, which is legislation that can cause uncertainty, there is a strong belief that continued use will be allowed - given the stringent safeguards that new sealed plants, together with closed-loop transfer systems such as the SAFE-TAINER system developed by SAFECHEM and appropriate solvent training, e. g. offered under the CHEMAWARE umbrella, is provided. Remember also that the REACH legislation clearly states that the essential use of a substance shall be authorized by authorities if it can be demonstrated that compliance with a recognised exposure limit can be achieved. The SCO EL recommendation of a 10 ppm exposure limit is achieved with modern closed cleaning equipment and appropriate handling. This reinforces the view that trichloroethylene has a long term future which involves active risk management: right equipment, the right handling processes and systems, aiming to confirm use of service elements extends useful life of solvent, and properly trained operators. This allows extended use of small amounts of solvent. In an independent study done by the European Commission, the environmental and economic consequences of the introduction of additional Chemical Product Services in the field of metal cleaning have been analyzed. The results were significant: for the removal of 100 kg oil from the surface around 754 kg of solvent is used in open top cleaning machines, whereas with closed cleaning equipment together with the safe supply and maintenance of the solvent with special service elements, the amount of solvent to clean 100 kg oil can be reduced to 15 kg, which results in a reduction of 98%.
The spill free use of chlorinated solvents in modern handling systems gives them an excellent environmental profile: They have low Photochemical Ozone Creation Potentials, they are not ozone depletors and they have low Global Warming potentials. They aren't implicated in the formation of acid rain, they are almost endlessly recyclable and they are extremely energy efficient in use. Low waste volumes are also a benefit.
Solvents for approved processes
Like NEU-TRI E trichloroethylene, DOWPER MC perchloroethylene has a wide range of approvals from major aerospace OEM's and has recently been submitted for testing with titanium to ASTM F 945-06 (Stress Corrosion of Titanium Alloys by Aircraft Engine Cleaning materials [Method A]). All tests with DOWPER MC were found by ASTM International to show "No evidence of cracking" and were reported by them to conform to the standard. DOWPER MC is widely used as an alternative to trichloroethylene in a range of plants.
MECTHENE MC methylene chloride is a low boiling point option which can easily be used in modern low emission plants. Like the above mentioned chlorinated solvents it can easily be monitored using simple, easy to use test kits and its safe working life extended using aligned stabiliser concentrates. All of these solvents are supplied in the SAFE-TAIN ER closed loop transfer systems which help to ensure safe storage in line with DEFRA recommendations and virtually emission free transfer of solvent. This not only saves solvent but greatly reduces operator exposure.
If chlorinated solvents cannot be considered, DOWCLENE 1601, a non-chlorinated solvent based on modified alcohols, has also been submitted for testing with titanium and passed all of the tests. The first formal aerospace approval for DOWCLENE 1601 has already been received, although formal publication is awaited. In full vacuum systems this cleaning agent offers an excellent option to chlorinated solvents and is already in use with major companies, such as airlines and turbine manufactures, across Europe.
Now consider some of those alternatives
The aqueous option is undoubtedly a good option in the right circumstances. But, what if you need dry components? What about energy consumption? What about waste volumes? Aren't global warming and water issues (both pollution and scarcity) major environmental impacts? Is the legislation that affects these impacts as fully developed as those for solvents? If not, how can you be certain that any capital decision is an appropriate one? Can you be certain that it will clean every soil from every substrate that is likely to be encountered? The solvent that you are looking to replace seems to have done so for a long time.
Non chlorinated solvents are heavily promoted. But do they offer any real benefits? Fluorinated solvents are expensive, don't have the range of approvals that exist for other solvents and, in some cases at least, have high global warming potential. They have high exposure limits, but at that cost, who wants lots of it to escape?
Brominated solvents, again, are heavily promoted but, at the very least, doubts exist about their regulatory status (see the US National Toxicology Program report TR-564 on http://ntp.niehs.nih.gov/go/34797) let alone the final decision of the European Courts of Justice about whether the R60/R11 risk phrases were appropriate for all nPB brands.
Hydrocarbon solvents in sealed, vacuum plants have been used, albeit not extensively in the UK, but experience has shown that often corrosion occurs due to the breakdown of soils in the still. Unlike DOWCLENE there is no easy mechanism to monitor for this or adjust when necessary.
In all, there is no magic option. Chlorinated solvents still remain the first choice for many users, especially in approval driven applications. And there are solutions to use them environmentally responsibly, safely, and sustainably.
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|Date:||Jul 1, 2011|
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