Effects of water quality on corrosion and scaling of the water meter by batch simulation test

• Main Authors: Tseng, Chih-Huan, 曾治寰
• Other Authors: Huang, Chih-Pin
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/txjd2w

碩士 === 國立交通大學 === 環境工程系所 === 107 === The existence of scaling in the water meter suspected to the outcome of corrosion was found to adversely affect the usage of tap water. The sediments (scaling) accumulated in water meters could not only decrease the amount of water distributed to the household but also induce inaccurate measurement of water meter. It was known that the severity of corrosion and scaling in different area can be various due to the inconsistent of water quality. Therefore, this study aimed to clarify the effects of water quality on corrosion and scaling of the water meter by batch simulation test. The experiment was conducted by immersing yellow brass of the water meter into the tap water. Sodium hypochlorite, calcium sulfate and sodium bicarbonate were introduced respectively into each of the sample for the soaking test. Simultaneously, the soaking test was separated into the beaker and the centrifuge tube soaking test to simulate the condition of half full tube and full tube in the real pipeline systems. The result showed that the highest corrosion penetration rate (0.15 mpy) and promotion efficiency (69.7%) were detected when yellow brass exposed to high concentration of chloride. Moreover, the largest corrosion (9.88π) and scaling area (34.6 mm2) were also obtained. However, the amount of calcium or sulfate existed in the water presented a slightly minor impact on not only the corrosion penetration rate (0.13 mpy) and promotion efficiency (65.1%), but also on the corrosion (6.61π) and scaling area (21.3 mm2). On the other hand, apparent alleviation of corrosion and scale formation were observed when the alkalinity of the water was higher. The effect of air exposure showed insignificant differences on corrosion and scale formation of the sliced water meter. In addition, corrosion and fouling are closely connected and inseparable. In certain water environments, such as the significant evidence of chloride or calcium ion and sulfate, there will cause obvious corrosion and scaling. The corrosion reaction occurs first, causing the problem of metal dissolution, and then it is produced according to different water quality. The formation of scale is accompanied by the corrosion pattern, that is, the result of corrosion.