specifications due to the changes made by controls manufacturers to comply with RoHS restrictions on the use of lead. This includes specifying an ISA Class G1 environment for control rooms, where in the past, a Class G2 environment was considered acceptable. Specifications are also now emerging that require the measurement and quantification of both copper and silver corrosion rates according to ISA 71.04-2013, with environmental severity levels determined according to the higher of the two. Although the amount of silver on printed circuitboards and other electrical components has been reduced by many control systems manufacturers, the use of silver is still required and will be for the foreseeable future. With this comes an increased concern over equipment reliability when using a copper-only environmental classification system. Example: problems with RoHScompliant equipment. A recycledpaper mill began a project to replace obsolete equipment that could no longer be supported with new DCS and programmable logic controls (PLCs). The original hardware had been installed for 15 years, and had proven to be reliable and robust. Many of the locations where this equipment had been installed were classified as ISA Class G1 for copper. However, the corresponding silver corrosion rates were up to 20 times higher, and essentially all of the silver corrosion reported from the analysis of CCCs collected over several years was due to sulfur corrosion. This presented some concern based on changes to the equipment due to RoHS compliance. Within three months of replacing the old systems, the mill began experiencing frequent failures of the input/output (I/O) stations installed on the process fieldbus (Profibus). A great deal of work was put into making the error-free,http://www.gemu.com http://adlinks.chemengonline.com/66424-14 http://WWW.CHEMENGONLINE.COM