The assembly shall consist of two positive seating check valves located between two resilient seated shutoffs with a hydraulically balanced bypass line and four test cocks.

• 这种总成应该由两个正向密封止回阀，两边夹着两个弹性阀座关闭阀，并配置一个液压平衡旁路管线和四个测试旋塞构成。