本powerpoint演示文稿首先提供回流产品和标准的列表，然后讨论设计标准的要素，包括:质量； 行业意识； 应用 环境 预期寿命 现场试验的可靠性； 材料；可修复性；压力损失；特色；生产容易；简单还有，成本。

This powerpoint presentation begins by providing a list of backflow products and standards, and then discusses elements of design criteria, including: quality; industry awareness; application; environment; life expectancy; reliability during field test; materials; repairability; pressure loss; unique features; production ease; simplicity; and, cost.