20-14: Advances in the Monitoring and Control of Cooling Systems ChemistryMonitoring and control of cooling water chemistry has improved considerably over the past few decades. Initially, chemicals were metered into the cooling water in proportion to blowdown water flow. The blowdown flow was either measured directly or, more typically, imputed from a makeup water flow meter. The concentration of water treatment chemical was controlled by manually adjusting the delivery rate of a metering pump by timing the drawdown using a