Series 774XDCDA contains two independently operating check valves located between two resilient seated shutoffs with four ball valve type test cocks and a hydraulically balanced metered bypass line to detect low flows.

• 系列774XDCDA包含两个独立运行的止回阀，位于两个弹性阀座关闭阀之间，并配置四个球阀型测试旋塞，以及一个液压平衡仪表旁路管线用于检测低流量。