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www.durr-ecoclean.com The new Generation of solvent-based parts cleaning. Optimized cleaning quality, reduced cost, high flexibility. Dürr Ecoclean meets the rising demands in industrial parts and surface cleaning with a complete new system concept for solvent cleaning. EcoCCore PARTS CLEANING 34 JUNE 2017 — PFonline.com Water Chemistry The water used in an aqueous system will have a direct impact on performance and maintenance requirements of the unit. In general, low hardness water is preferred. This will reduce the formation of hard water soaps that can consume rust-inhibiting components, along with forming scale and sludge. However, when using aqueous rust inhibitors, the chloride and sulfate levels are concerning. Chlorides and sulfates will accelerate corrosion and become more problematic over time. As water evaporates, the remaining contaminants are condensed, increasing the water hardness within the solution. These levels need to be monitored and held in check, using purified water and appropriate recharging of the final stage. All of the solids dissolved in the incoming water will ulti- mately be dried on the parts, affecting the results. The pH of the aqueous rust inhibitor stage needs to be maintained within the appropriate range recommended by the supplier. Even a slight reduction in alkalinity can reduce the corrosion resistance performance. Cast iron chip testing can be an effective KPI for the rust inhibitor solution. This can be done on site following the ASTM D 4627-12 procedure. The collected sample can be diluted to 50 percent in fresh water to create a stressed condition, reducing the product concentration to provide an indication of performance deterioration before the process actually fails. Humidity cabinet testing is effective for corrosion protection. Drying Prior to packaging, parts must be dried thoroughly. Ovens, forced heated air flow, air knives or drying media are all effective drying methods. Heating the process solution in the final stage will accelerate the drying process, but tempera- ture limits should not be exceeded for the specific chemistry. Parts must not be packaged or sealed if water remains, or corrosion will result. Conclusions Aqueous parts washing systems can provide great value, flexibility and reliable performance when properly used. Optimum programs begin with design and implementation, followed by careful maintenance and process control. By understanding the capabilities and limitations of the chemistry, and the overall process, an efficient and sustain- able system can be implemented while reducing the overall cost of operating the system. For information from Chemetall, call 908-464-6900 or visit chemetallna.com. David M. Gotoff is product manager at Chemetall, part of the BASF Group.