PRE-TREATMENT , SURFACE PREPARATION , DEGREASING & CLEANING
As with coatings , cleaning systems have had to change . With increasingly demanding standards of cleaning required for precision engineering , electronics , optics etc solvents are often first choice , for reasons outlined above , but these have been targeted by regulators and alternatives are encouraged by the relevant authorities and law makers often without serious consideration of unintended consequences .
For example , water-based cleaning is encouraged as the obvious alternative , but this has many disadvantages compared to condensation cleaning as although the machines are simple and relatively cheap the processes require multiple heated tanks for immersion or spray processing or long programmed cycles in batch machines for cleaning , rinsing , and drying . Water based processes are slow , energy intensive and occupy more floor space than solvent-based condensation cleaning equivalents where only one tank with a small footprint is needed , delivering shorter process times and , most importantly for the environment , using minimal energy .
The ideal cleaning process would be “ Condensation Cleaning ” using water but due to the physical characteristics of the water vapour / steam and the inability to carry onto the surface of the targeted parts surfactants to remove the oil , grease and soils and the difficulty and expense of rinsing and especially drying this can only ever be a dream .
Historically chlorinated hydrocarbons have been the solvents of choice for the “ Condensation Cleaning ” process . Compatible with most materials of manufacture , stable in constant use , producing a non-flammable saturated vapour three to four heavier than air at a temperature greater than ambient .
The traditional solvents such as trichloroethylene exhibits all these
characteristics however concerns about its carcinogenic properties and the danger to operators by exposure , led to a continuing search for a safer alternative . 1,1,1 trichloroethane based solvent formulations became popular in the mid part of the last century as a safer replacement . An excellent solvent , safer for users , it proved to be depleting the protective ozone layer around the Earth and was subsequently banned . With the development of the REACH legislation in Europe , trichloroethylene was again allowed with restrictions and stringent controls for use in authorised machines which control emissions to very low figures close to zero .
EnviroTech have been supplying vapour degreasing solvent formulations for 40 years constantly responding to increasingly stringent regulatory requirements for environmental and safety laws and the need for improved cleaning standards .
ProSolv ® 5408e is a new sustainable solvent blend with near zero OPD ( Ozone Depletion Potential ) and GWP ( Global Warming Potential ) for high performance degreasing and cleaning which ticks all the boxes with the perfect profile for a vapour degreasing solvent . Soft on the environment and safer for users with high performance , improved cleaning , and lower costs . Lower boiling point , economical with energy with low solvent losses , faster production , reduced costs , easy handling . Exceptionally low
surface tension to penetrate micron sized holes and close contact surfaces . Sustainable and secure for future use as your ‘ forever solvent ’.
As with all legislation for chemical use regulation and restrictions drive development of associated processes and equipment . Sealed tanks are now standard with many different designs available . The most common are discussed below .
The single tank hermetically sealed machines favoured by some manufacturers uses a process tank to contain the solvent and a separate storage tank / vapour generator . Baskets loaded with parts to be cleaned are introduced from the top or through access points on the side of the tank . Lids or doors hermetically seal the tank . Solvent is pumped into the process tank where agitation , ultrasonics or pumped liquid is circulated through the parts . Used Solvent is removed to the vapour generator , condensing coils controlling the vapour are linked to coils located in the vapour zone which , when the cycle is complete , collapse the vapour . The process tank is emptied . Controlled air introduced to process tank is then recycled through carbon absorption units to remove traces of solvent until the concentration is within regulatory standards when the lid is released for the basket of parts , clean and dry , to be removed and replaced with a further basket .
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40 MARCH 2022 twitter : @ surfaceworldmag