Solvents Tested by NASA for Critical Cleaning Tasks

NASA, the U.S. space agency, has a unique emphasis on reliability. NASA products are extremely expensive, have long operational lives, work with almost infinite sensitivity and operate in the harshest environment of all — outer space. So, it is reasonable that NASA is very cautious about introducing new technologies because problems, if any, may not become apparent for years.

The agency completed a test of cleaning fluids to replace older cleaning solvents. The study, by Mark Mitchell of the Marshall Space Center and Nikki Lowery of Jacobs Technology compared alternatives to n-propyl bromide (nPB), a popular benchmark solvent.

The tests compared the effectiveness of three new alternatives, including Chemours Vertrel® SDG specialty fluid. The tests were strictly controlled. The various test coupons were made from a steel alloy, magnesium or aluminum. The contamination was a mix of aircraft grease, a synthetic hydraulic fluid and a small quantity of carbon black. The contaminant was applied to the test coupons, baked for two hours at 55˚C and then aged for seven days. To clean, the coupons were immersed in boiling solvent for 30 minutes; observed and weighed.

The test results were quite good. As a benchmark, nPB removed 96% of the contamination. All of the others did “in the range of or better than” nPB. When tested on a roughened coupon instead of a smooth polished metal surface, all four products surpassed nPB.

While the authors cautioned that their results are not to be considered any sort of a commercial endorsement, they concluded the Chemours Vertrel® SDG fluid “cleaned the most consistently.” Additionally, “all but Vertrel SDG showed reduced cleaning effectiveness on aged contamination.” The authors cautioned that additional operational, commercial and toxicity factors should be considered before finalizing a solvent selection.