SAFER CLEANING CHOICES Replacing nPB for solvent cleaning

by Mike Jones, MicroCare Corp E

ngineers are always looking for alternatives to chemicals that may

have health concerns or cause environmental damage. Regulations and guidelines can be bewildering, especially with laws continually changing and redefining what companies can and can’t use. This being said, choices on cleaning products is limited. Companies are using aerosol cleaner packages with normal propyl bromide (nPB). These are highly effective cleaners with attractive prices, however the toxicity standards for these products are being tightened.

SAFER CLEANING CHOICES The European Chemicals Agency listed nPB as a ‘Substance of Very High Concern’ in December 2012. While nPB has been an acceptable choice for precision cleaning in tightly sealed cleaning systems for years, the use of nPB in aerosols is still proposed to be unacceptable, but a final ruling has not been published. This means the chemical legally can still be packaged within an aerosol. MicroCare does not package nPB into aerosol canisters. It is almost impossible to use any fluid in an aerosol package and keep exposures below 10 ppm. Testing at MicroCare determined that under the best conditions exposures for workers using aerosol cans are in the 10- 20 ppm and one could expect uncontrolled, high-pressure aerosols to generate substantially higher exposures. Here’s the key question: are the

intended replacements for nPB up to the job?

FIELD TESTS The criteria for which customers should be searching is clear: a nonflammable, fast-drying, highly aggressive solvent that cleans well, doesn’t damage the environment and has acceptable toxicity ratings. Most companies using aerosol degreasers use a simple visual inspection to confirm the parts are clean enough. Conversations with operators confirm they are looking for fast, safe, convenient ‘good enough’ cleaning. A suitable location to test cleaning results was at a


local auto transmission repair shop, which opened its workshop to cleaners and photographers from MicroCare. In this real-world field test, a wide variety of transmission parts were cleaned with two different nPB aerosol cleaners and one HFC-based aerosol cleaner. Operators judged the cleaning effectiveness to be very good on all three products, even when the residues were baked into place. When the parts were placed side-by-side after cleaning, operators could not detect a difference between the parts cleaned with the nPB and the parts cleaned with HFC-trans blends. Both types of chemistry are definitely

not ‘plastic-safe’. As a side-by-side test of their cleaning strength, the sprays were aimed at a soft plastic foam product. Both destroyed the foam instantly, suggesting that in terms of cleaning strength the materials operate in a highly similar manner. The nPB aerosols were packaged at higher pressures than the HFC-based cleaner, so those cleaning fluids came out faster and with more ‘scrubbing’ power. This is a function of the packaging and not the cleaner itself. Operators commented on how the HFC-based cleaner evaporated faster than the nPB-based cleaners. Since nPB

As a solvent, nPB is a powerful degreaser thst removes oil and grime quickly. Notice the overspray on the left from the high-pressure aerosol; this increases worker exposures

boils at 70˚C, about 40˚C higher than HFC blends, it should evaporate more slowly. This observation caused some divergent opinions. One operator thought fast-drying was convenient, the other operator felt he used more solvent because it evaporated quickly. Both noticed the HFC-based cleaner had far less aroma than the nPB-based cleaners and felt that this was a significant improvement.

MAKING THE RIGHT CHOICE Many industrial customers need a strong, nonflammable aerosol degreaser. However, it is clear there is no longer a need to use nPB-based aerosols. While these tests were not rigorously scientific and were conducted with a very small sample, these admittedly anecdotal conclusions strongly suggest that today there are viable choices on the market that are substantially safer than nPB. It seems reasonable that any well-

informed company buying aerosols containing nPB should be looking to change as soon as possible. Furthermore, any distributor selling aerosols filled with nPB aerosol should be concerned about product liability. Everybody should be helping their operators select and procure a newer, safer cleaning fluid. While companies pay a small premium

in price for these products, the improvements in worker safety are substantial.



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