Davis used similar variables to develop a model for corrosion rates in the presence of a specific inhibitor. Other models have been developed for internal use by major water treatment companies. A common problem to all models is relating their predictions to real world corrosion in operating cooling systems. Test data, by necessity, relies upon corrosion coupons or electrochemical methods as the basis for measuring corrosion rates. On the plus side, these are the same techniques used to monitor corrosion rates and treatment effectiveness in most cooling systems.
Results can very dramatically, even under the same water chemistry conditions.
A recent paper outlines the problem. Measured rates where one to two orders of magnitude higher on the precorroded coupons. They found the use of precorroded metal specimens to be critical to the success of using laboratory data to model an operating system in the field. This paper uses the basic method outlined by Pisigan to develop a baseline correlation for corrosion rate prediction, and for modeling the impact of inhibitors on corrosion rate. Models are then used to predict the inhibitor level requirement to achieve a specified corrosion rate target.