Normal water supply:

1、清洁市政生活水从第1级止回阀经过排水器到第二级止回阀出口向用户供水，第1级止回阀进口高压水通过高压软管进入排水器隔膜上腔，而阁膜下腔与第1级止回阀出口(第二级止回阀进口)相通，由于其存在一定的压差，推动阀瓣下移，排水器关闭，防止隔断阀正常供水。

1. Clean municipal domestic water is supplied to users from the first stage check valve to the second stage check valve outlet through the drainer. The high-pressure water at the first stage check valve inlet enters the upper chamber of the drainer diaphragm through the high-pressure hose, and the lower chamber of the diaphragm is connected with the first stage check valve outlet (the second stage check valve inlet). Due to its certain pressure difference, the valve disc is pushed down, and the drainer is closed to prevent the normal water supply of the block valve.

2、当阀门后的管路无用户，水静止。如进口压力保持不变，其前后存在压差，排水器仍呈关闭状态。

2. When there is no user in the pipeline behind the valve, the water is still. If the inlet pressure remains unchanged, there is a pressure difference before and after it, and the drain is still closed.

3、如进口压力下降，一共前后压差下降到一定值时，弹簧推动阀瓣向上，排水器又开启泄压，泄压到与进口压力恢复定压差时，排水器又关闭。

3. If the inlet pressure drops, when the total pressure difference between the front and back drops to a certain value, the spring pushes the valve disc upward, and the drainer opens again for pressure relief. When the pressure is relieved to a constant pressure difference with the inlet pressure, the drainer closes again.

密封失灵时：

In case of seal failure:

1、防污隔断阀之后管网压力升高，超过阀前进口压力时，如第二止回阀密封完好无渗漏，高压水不会倒流，排水器隔膜上下保持原来压差，排水器关闭，不泄压。

1. When the pipe network pressure rises after the anti-pollution isolation valve and exceeds the inlet pressure in front of the valve, if the second check valve is sealed well without leakage, the high-pressure water will not flow back, the original pressure difference between the upper and lower parts of the drain diaphragm is maintained, and the drain is closed without pressure relief.

2、当第二级止回阀密封破坏产生渗漏，第二级止回阀之前压力升高，造成排水器一个膜上下压力并减小，排水器打开，排水泄压 。

2. When the seal of the second-stage check valve is damaged and leakage occurs, the pressure in front of the second-stage check valve increases, resulting in a decrease in the upper and lower pressure of a membrane of the drainer, and the drainer opens to drain and relieve pressure.

3、此时，如第1级止回阀同时密封被破坏，由于第二级止回阀倒流回的高压水已泄压减压，故不会倒流第1级止回阀。

3. At this time, if the seal of the first stage check valve is damaged at the same time, the high pressure water flowing back from the second stage check valve has been depressurized, so it will not flow back to the first stage check valve.

如供水过程中供水压力不断下降，则排水器隔膜上部压力下降，排水器控制弹簧推动阀芯打开排水器排水。当进口压力下降零或负压时，排水器完全打开，水排出，空气从排水器进真空腔，从而防止产生虹吸倒流现象。上海良工阀门,武汉良工阀门,良工阀门

If the water supply pressure continues to drop during the water supply process, the pressure at the upper part of the drain diaphragm will drop, and the control spring of the safety drain will push the valve core to open the drain to drain. When the inlet pressure drops to zero or negative pressure, the drainer is fully opened, the water is discharged, and the air enters the true cavity from the drainer to prevent siphon backflow. Shanghai Lianggong Valve, Wuhan Lianggong Valve, Lianggong Valve

安装部位

Installation position

1、自来水管网接入用户的接户管水表后面 。

1. The water pipe network is connected to the back of the user's household pipe water meter.

2、生活用水管道上接出非生活用水和排污管，安装于接出管起端。

2. Non-domestic water and sewage pipes are connected to the domestic water pipe and installed at the beginning of the outlet pipe.

3、生活饮用水水箱的进水管上（水箱底部进水时）。

3. On the inlet pipe of the domestic drinking water tank (when water enters the bottom of the tank).

4、生活饮用水管道上串联加压泵时安装于泵吸水管上。

4. The booster pump is installed on the pump suction pipe when the domestic drinking water pipeline is connected in series.