The parts washers are used primarily to remove oil, grease and dirt from metal equipment parts during routine maintenance. Pursuant to the May 1997 Orders, Mead replaced 36 solvent based parts washers with 17 aqueous-based cleaning units. The aqueous units, manufactured by Graymills and Precision Metal Works, are versatile, and address a number of different cleaning needs at the Mill. The vendor performed on-site trials of the aqueous units. The PMW units operate much like an automatic dishwasher, and work by spraying the parts with hot water and soap, while the parts rotate on a turntable.
Water acts as the solvent, with assistance from a powdered soap supplied by the vendor.
A second type of unit, made by Graymills, replaces the sink on a drum type parts washers used to clean parts by hand. The fluid is recycled through the system and filtered. The new aqueous washers prevent dermal contact with solvents and inhalation of solvent vapors by operators, which is a common problem with sink on a drum type solvent-based parts washers. There are many different types of soap and additives available for the wide variety of aqueous parts washers. The soaps have differing chemistries to control factors such as cleaning, spotting, foaming, and rust prevention.