Much work has been done in recent years in the development and promotion of non-chromate cooling water corrosion inhibitors. One of the main reasons for this effort is the environmental legislation restricting, and in some cases prohibiting, the discharge of toxic materials into public waters. Early in 1970 we decided to run trials on several of these non-chromate inhibitor programs to determine what results to expect in our system if we were to use one of them to meet these restrictions. When we started this program we soon found we did not have sufficient monitoring apparatus installed in our systems to accumulate enough data during a short trial period to make any valid comparisons so we added to and modified our equipment until we settled on the system we are now using. This equipment includes a test heat exchanger, coupon station, wire resistance probe, and instantaneous probes, all of which are mounted in the return water header. Another problem we encountered was routine control of chemical feeding equipment and tower operation by the plant operators was less than ideal. As a result, all of the trials had times when the pH or cycles of concentration were not in the recommended range or the chemical feed rate was too high or too low. We decided that we would live with this since this degree of control is all we could expect on a routine basis if any of these programs were instituted permanently. We feel that in spite of the less than ideal controls the trials were valid for our comparison and evaluation purposes since the upsets that had to be taken into account for the trials were the same type of upsets that we would have to live with under routine operation, and a program that did not work with trial upsets would not work on a routine basis.
