Swing-type check off er the least pressure drop and offer simple automatic closure; when fluid flow stops gravity and flow reversal closes valve.
旋启式止回阀压降最小，能够完全自动关闭，即在介质流动停止、重力和介质倒流的状态下自动关闭阀门。
2
Students check the automatic drain valve of the front end of the valve is open.
检查自动排水阀前端之球阀是否打开。
3
Checkvalve before the valve is to use the pressure after poor hoist the automatic valve, it is the role of the media flows only in one direction, reverse and stop its flow.