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This post was last edited by yuchenchf on 2015-8-24 at 15:54. Lithium bromide solution is a highly corrosive medium; it has a strong corrosive effect on common metal materials such as carbon steel and copper. In the past, for a long period of time, the development of lithium bromide absorption chillers was greatly restricted due to the difficulty in properly addressing corrosion issues. The corrosion of metal materials by lithium bromide solutions not only **shortens the service life of refrigerators**, but the corrosion also produces rust and non-condensable gases (such as hydrogen), which directly affect the performance and proper operation of the unit. Therefore, understanding the corrosivity of lithium bromide solutions to metal materials in order to propose anti-corrosion measures is an important issue in lithium bromide absorption refrigeration systems. Through extensive experimental research, this issue has been largely resolved. Based on the corrosion tests of lithium bromide solutions inside the units, the main factors affecting corrosion are summarized as follows: (1) Effect of oxygen: Whether in laboratory simulation tests or during actual use in the units where contact with oxygen occurs, corrosion is particularly severe. For example, in lithium bromide absorption chillers, although the temperature and concentration of the solution in the generator are relatively high, corrosion is low because the solution in contact with oxygen is limited. In areas such as the upper part of the absorber and the evaporator water pan, lithium bromide solution splashes during the operation of the unit, forming a very dilute solution film that is susceptible to oxygen attack, resulting in severe corrosion. Therefore, oxygen is the most important factor that promotes corrosion. (2) Solution concentration: At normal pressure, corrosion increases as the concentration of the lithium bromide melt decreases, because the solubility of oxygen is higher in dilute solutions than in concentrated ones ； At low pressures, the corrosion rate of metal materials has little to do with the concentration of the solution, as the oxygen content in the solution is very low. (3) Temperature tests on the solution showed that, for solutions without lithium chromate corrosion inhibitors, the corrosion rates of A3 steel, red copper, and nickel-copper all increased as the temperature rose. In the solution containing lithium chromate as a corrosion inhibitor, the corrosion rate of A3 steel decreases significantly as the temperature rises. This may be because lithium chromate has better passivation properties at high temperatures than at low temperatures. (4) pH value of the solution: The pH value is an indicator of the acidity or alkalinity of a solution. The pH value is 7, so the solution is neutral ； Below 7 is acidic ； Above 7, it is alkaline. The pH value of a solution can be easily measured using an indicator. Acidic solutions certainly cause severe corrosion of metal materials ； For alkaline solutions, when the pH is in the range of 8.0–10.2, as the pH value increases, the corrosion of steel decreases slightly, while that of copper increases slightly. Only an excessively high pH value is beneficial for the passivation of both A3 steel and red copper, as it accelerates corrosion. Tests have shown that a pH value of the lithium chromate solution in the range of 9.5–10.3 is favorable for the corrosion inhibition of metal materials, especially A3 steel.