Product

backflow preventer

Brand：Pneumatic eccentric butterfly valve 型号：DF41X-16

The following is a detailed explanation of Backflow Preventer, covering its definition, classification, working principle, application scenarios, and selection points:
1. Definition and Function
Backflow preventer is a safety device that prevents the reverse flow of medium in pipelines, mainly used to protect drinking water systems from pollution. When the pressure in the water supply pipeline is abnormal (such as water stoppage or negative pressure), it can effectively prevent sewage, chemicals, etc. from flowing back to clean water sources, avoiding public health risks.
2. Core classification
According to the differences in protection level and structure, backflow preventers are divided into the following main types:
Type characteristics Applicable scenarios
The double check valve type consists of two independent check valves connected in series, with a drainage chamber in the middle. It has a simple structure and low cost. Low risk areas (such as water supply for ordinary buildings)
The pressure reducing backflow preventer adds a pressure reducing valve on the basis of a double check valve, which can adjust the outlet pressure and prevent high-pressure backflow. Medium to high-risk areas (such as hospitals and laboratories)
The air partition type completely isolates the pollution source through physical air gaps (such as drains), with the highest level of protection. High risk areas (such as chemical and pharmaceutical industries)
The dynamic pressure difference type uses pressure difference to automatically control the opening and closing of the drain, with fast response speed, suitable for systems with frequent pressure fluctuations. Industrial circulating water system
3. Working principle
Double check valve structure: When flowing forward, both check valves open simultaneously; If the pressure drops, the first stage check valve closes, and the second stage check valve closes due to gravity or spring force. The middle chamber is emptied through a drain, forming an air partition.
Pressure reducing type: Maintain stable outlet pressure through a pressure reducing valve to avoid backflow caused by excessive downstream pressure.
Air partition type: The drain directly discharges into the atmosphere, ensuring that the polluting medium cannot flow back through any path.