Corrosion of Copper Coils in Computer Air Handlers

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Product Number: 51315-5963-SG

ISBN: 5963 2015 CP

Author: Todd Mintz

Publication Date: 2015

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Computer Room Air Handlers at a data facility experienced localized corrosion after a few months of operation. Initial testing indicated that the potential cause of corrosion was due to a process known as formicary corrosion. The source of the corrosion was investigated by performing air sampling of the data hall prior to and during the floor cleaning process as a way to determine whether the chemical cleaners could be responsible for the accelerated corrosion. While some aggressive species were identified prior to the floor cleaning including Formate the measured levels of Formate during the cleaning process were elevated from the initial baseline readings. Furthermore Acetate which was not measured in the baseline readings was measured during the cleaning process. Two types of chemicals are used to clean the data hall. Cleaner A is composed of two chemicals one being alcohol based and the other contains acetate groups. The cleaner B is composed of a long chained carbon and oxygen chemical. Based on the air sampling results the copper corrosivity of the two cleaners were tested. The experimental test consisted of filling a clean jar with the individual cleaning solutions diluted to ratios of either a 1:1 6:1 or 12:1 with deionized water (DI). In addition jars with only DI were used in the study. Copper tubes were maintained in the vapor space of the jars and exposed to a cyclic temperature between room temperature (?24 °C) and 40 °C. The samples were exposed for 30 days. The results of the test showed pitting on all samples yet only the material exposed to Cleaner A showed deep penetrating corrosion. While the largest degradation (roughly halfway through-wall) was observed on the tubes exposed to the 1:1 Cleaner A to DI the amount of degradation appeared to trend linearly with the concentration of Cleaner A. From these results it appears that the chemicals in the Cleaner A solution have the ability to lead to significant degradation in the copper tubing.