flap check valve

例句：

1. 1. The new design ofthe flap check valve has greatly improved itsefficiency.
   新的瓣式止回阀设计大大提高了其效率。
2. 2. In the process of oilrefining, the flap check valveis used to prevent oil leakage.
   在石油精炼过程中，瓣式止回阀用于防止油泄漏。
3. 3. The engineercarefully checked the flap checkvalve before starting the project.
   工程师在开始项目之前仔细检查了瓣式止回阀。