Full Description

Scale build-up, corrosion rate, and metal release associated with drinking water distribution system plumbing are related to the oxidant type and concentration. Conversely, different distribution system metals will exert different oxidant demands. Oxidizing conditions will likely impact the nature and protective qualities of metal corrosion byproduct scales, and metal release rates. However, the relationships are not well understood. The objective of this research was to study the relationship(s) among redox potential, oxidant type, oxidant concentration, metal release rate and corrosion scale properties of drinking water plumbing materials (copper, lead, iron, and red brass). The research was conducted using a test loop apparatus consisting of a 100 liter Nalgene water reservoir connected to eight parallel test loops by polyvinylchloride (PVC) pipe. The test water reservoir had a recirculation pump system for mixing and a separate pump system to feed test water to the loops. All pump components in contact with the test water were constructed of metal-free materials. Each test loop contained one approximately 480 mL sample holding cell. The sample holding cells were equipped with ports for a pH meter and a redox potential electrodes. Two 1"x 2"x 1/8" metal coupons with a total surface area of 9.5 in 2 yielded a surface area to volume ratio of 0.02 in2/mL. The system simultaneously ran two sample cells (duplicates) of each metal as an internal check of reproducibility. Platinum combination, with silver-silver chloride reference cells, redox electrodes have been used for in the test loop apparatus system. These redox electrodes have been compared to known standard solutions (ZoBell's and Light's Standard solutions and the Metrohm commercial standard solution) on an approximate biweekly basis to monitor and ensure accurate measurements. Includes table, figures.

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Edition: Vol. - No. Published: 11/01/2002 Number of Pages: 10File Size: 1 file , 440 KB