低阻力倒流防止器

产品描述 Product Description

低阻力倒流防止器由进口止回阀、出口止回阀、泄水阀及球阀管路等组成。管道水正常流动时，进口处的供水压力总高于出口处的压力，水直接流过倒流防止器，此时进口处压力与中腔压力形成一个压力差。此压力差驱动泄水阀处于关闭状态，泄水阀不泄水。当流量为零时，进出口止回阀均关闭，此时由于止回概弹簧的作用，进口处压力仍高于中腔压力，泄水阀依旧保持关闭状态。当由于一些原因出口压力增高或进口压力降低，当出口压力高于进口压力时，排水阀打开泄水，将中腔内的水排出，避免管路水倒流污染主管网。当主管网检修或由于一些原因停水时，进口压力下降到一极小压力时，泄水阀全开泄水，空气进入中腔，形成空气隔断。不管进口压力降到多小即使为负值，也不会产生虹吸现象污染主管网。

The low resistance backflow preventer consists of an inlet check valve, an outlet check valve, a drain valve, and a ball valve pipeline. When the pipeline water flows normally, the water supply pressure at the inlet is always higher than the pressure at the outlet, and the water directly flows through the backflow preventer. At this time, the pressure at the inlet and the pressure in the middle chamber form a pressure difference. This pressure difference drives the drain valve to be closed, and the drain valve does not release water. When the flow rate is zero, both the inlet and outlet check valves are closed. At this time, due to the action of the check spring, the pressure at the inlet is still higher than the pressure in the middle chamber, and the drain valve remains closed. When the outlet pressure increases or the inlet pressure decreases due to some reasons, and the outlet pressure is higher than the inlet pressure, the drainage valve opens to discharge the water in the middle chamber, avoiding the backflow of water in the pipeline from polluting the main pipe network. When the main network is repaired or the water supply is shut down due to some reasons, the inlet pressure drops to a very small pressure, and the water release valve is fully opened to release water. Air enters the middle chamber, forming an air partition. No matter how low the inlet pressure drops, even if it is negative, there will be no siphoning phenomenon that pollutes the main network.

结构图 Structural diagram

该阀主要由进口止回阀、泄水阀（空气隔断机构）、出水止回阀、外接管路、控制球阀等组成如下图所示：

螺纹连接倒流防止器构示意图 Schematic diagram of threaded connection backflow prevention device structure

1-上游球阀 2-检测球阀1 3-倒流防止器主体 4-检测球阀2 5-检测球阀3 6下游球阀7-泄水阀
 8-泄水阀出水口

1-Upstream ball valve 2-detection ball valve 1 3-backflow protector body 4-detection ball valve 2 5-detection ball valve 3  6 downstream ball valve 7-drain valve
8-Water drain valve outlet

法兰连接倒流防止器结构示意图 Schematic diagram of flange connection backflow preventer structure

1-上游闸阀 2-过滤器 3-倒流防止器主体 4-检测球阀1 5-检测球阀2 6-检测球阀3 7-下游球阀 8-泄水阀 9-泄水斗

1-Upstream gate valve 2-filter 3-backflow protector body 4-test ball valve 1 5-test ball valve 2 6-test ball valve 3 7-downstream ball valve 8-drain valve 9-drain bucket

工作原理Working principle

 A、正向通水：
进口压力大于出口压力时，两个止回阀瓣开启，排水器关闭。在2m/s流速时，流通水损小于0.04Mpa.  forward water flow:
When the inlet pressure is greater than the outlet pressure, the two check valves are open and the drain is closed. At 2 m/s flow rate, the circulating water loss is less than 0.04 Mpa.

B、反向关闭：
进口压力小于等于出口压力时，两个止回阀瓣关闭，排水器开启。如果没有垃圾卡阻，两个止回阀瓣密封关闭，排水器出口不排水，中间腔与大气相通，中间腔压力为零。reverse closed:
When the inlet pressure is less than or equal to the outlet pressure, the two check valves close and the drain is open. If there is no garbage block, the two check valves are closed, the drain outlet does not drain, the middle cavity is connected with the atmosphere, and the pressure of the middle chamber is zero.

C、防止回流污染：
进口压力小于出口压力时，两个止回阀瓣处于关闭状态，排水器处于开启状态如果其中一个或两个止回阀瓣的阀口有垃圾卡阻，产生渗漏，所漏介质均流向中间腔，经过排水器直接排出阀外，防止对进口端的回流污染。注：P1为进口端压力，P2为中间腔压力，P3为出口压力。Prevent backflow pollution:
When the inlet pressure is less than the outlet pressure, the two check valve valves are in the closed state, and the drain device is in the open state. If one or two of the check valve valves have garbage blocked, causing leakage, the leakage medium flows to the middle cavity, and the valve is directly discharged through the drain device to prevent the backflow pollution of the inlet end. Note: P1 is the inlet pressure, P2 is the intermediate chamber pressure and P3 is the outlet pressure.


功能和特点Function and characteristics


①由前后两个止回阀和中间自动排水器组成 It consists of front and back check valves and intermediate automatic drain.


②在前后止回阀产生渗漏时，能够自动排水，阻断回流，严格防止回流污染，保护上游管道内的水质When the front and rear check valves produce leakage, they can automatically drain water, block backflow, strictly prevent backflow pollution, and protect the water quality in the upstream pipeline.


③超低水损、节能显著：水头损失小于0.04Mpa。Ultra-low water loss and significant energy saving: the head loss is less than 0.04 Mpa


④空气隔断、自动排水：在回流状态发生时，主阀关闭时，排水器自动开启、中间腔泄压为零，主阀的上下游之间实现空气隔断或零压隔断，隔断性能安全可靠。Air partition, automatic drainage: when the reflux state occurs, when the main valve is closed, the drainage device automatically opens, the middle cavity pressure relief is zero, between the upstream and downstream of the main valve to achieve air partition or zero pressure partition, partition performance is safe and reliable.


⑤节地节材、安装灵活：外形小、自重轻，结构长度仅为现有同类产品的30%；可以水平或垂直安装。Flexible installation: small appearance, light weight, structure length is only 30% of the existing similar products; can be installed horizontally or vertically.


压差与流量曲线 

水损曲线图

安装示意图

图中 1为闸阀、2倒流防止器、3为过滤器

法兰式

内螺纹式