DEGASSED CATION CONDUCTIVITY MEASUREMENT

This paper discusses the measurement and interpretation of degassed cation conductivity (DCC). There are three designs of DCC instruments: reboiling before or after cation exchange and nitrogen sparging after the cation column at ambient temperature. Each of these designs yields different results. Reboiling before cation exchange only removes free CO2. However, cation exchange converts all salts to acids, which are more volatile than salts, and reboiling after cation exchange removes most carbonates and portions of the volatile acids. In addition, the following instrument design and water chemistry factors influence the measured DCC: reboiling vs. sparging, purity of the sparging gas, intensity and length of degassing, removal of vapors, temperature compensation from ~100°C to 25°C (for reboiled DCC), effectiveness of cation exchange, and pH and type of alkalizing agents, salts, and acids in the sample. The main question is about the meaning of the various DCC measurements in relation to corrosion and flow-accelerated corrosion.