The control of corrosion in overhead condensing systems has traditionally depended on various rules-of-thumb to determine the amount of neutralizing amine needed to control corrosion. Most often, the pH of the accumulator water is used to set and adjust the chemical rate. Methods such as this have often not been completely successful because they do not take into account conditions in the area of initial water condensation and the deposition potential of the salts of the
neutralizing amines that are used to control the pH of the system. Experimental work has resulted in the development of new neutralizing amine products and software models that help overcome the problems experienced in the past. The theories governing the change of pH with amount of water condensed and ammonium chloride and amine hydrochloride salt deposition are discussed. Demonstrations of the use of the software and chemistry are given. Keywords: overhead corrosion, neutralizing amines, first drop pH, vapor-liquid equilibrium, VLE, vapor-liquid distribution ratio, ammonium chloride, neutralizing amine hydrochloride, salt deposition potential