Abstract:
Polyethylene (PE) pipes have been widely used in drinking water distribution systems across the world. In many cases, chlorine dioxide (ClO2) is used to maintain a residual disinfectant concentration in potable water. Practical experiences have shown that the lifetime of PE pipes is significantly reduced due to exposure to drinking water with ClO2. Recently, many companies have proposed new PE pipes with a modified formulation, which are more resistant to chlorine dioxide. However, a standardized test method for evaluating the long-term performances of PE pipes is still missing. This literature review was performed to provide a description of chlorine dioxide uses and degradation mechanisms of polyethylene pipes in real water distribution systems. Current accelerated aging methods to evaluate long-term performances of PE pipes exposed to ClO2 are described and discussed along with the common technics used to characterize the specimens. Accelerate aging methods can be distinguished in immersion aging tests and pressurized pipe loop tests. Wide ranges of operational conditions (chlorine dioxide concentration, water pressure, water temperature, etc.) are applied, resulting in a great variety of results. It was concluded that pressurized looping tests applying semi-realistic operational conditions could better replicate the aging mechanisms occurring in service. Despite this, the acceleration and the evaluation of the long-term performance are still difficult to determine precisely. Further experimentation is needed to correlate chemical-mechanical characterization parameters of PE pipes with their lifetime in service.
摘要:
背景技术聚乙烯(PE)管道已经广泛用于全世界的饮用水分配系统。在许多情况下,二氧化氯(ClO2)用于维持饮用水中残留的消毒剂浓度。实践经验表明,由于暴露于含有ClO2的饮用水,PE管的寿命显著缩短。最近,许多公司提出了改进配方的新PE管,对二氧化氯的抵抗力更强。然而,评估PE管道长期性能的标准化测试方法仍然缺失。进行此文献综述是为了描述二氧化氯的使用和聚乙烯管道在实际配水系统中的降解机理。描述并讨论了当前用于评估暴露于ClO2的PE管的长期性能的加速老化方法,以及用于表征样品的常用技术。在浸没老化试验和加压管道回路试验中可以区分加速老化方法。广泛的操作条件(二氧化氯浓度,水压,水温,等。)被应用,产生了各种各样的结果。结论是,应用半现实操作条件的加压循环测试可以更好地复制在服务中发生的老化机制。尽管如此,加速和对长期绩效的评估仍然很难准确确定。需要进一步的实验来将PE管的化学机械表征参数与其使用寿命相关联。