Vent the piping and test valvebody cavity to remove air or steam.
排放管道和试验阀门体腔内的空气或蒸汽。
2
Valvebody and bonnet are separated by diaphragms in order to prevent valve parts, such as bonnets and steam from corrasion;
阀体与盖被中间隔膜隔开，使得隔膜上方的阀盖，阀杆等零件不受介质侵蚀；
3
When the water level of condensate in the drain sump drops, the cup to shut the admission pipe falls down, the passage for steam to enter into the valvebody is opened.