Classification of the type of backflow preventer, composition of backflow stopper

Here are some of the well-known brands recognized in the backflow preventer industry that are widely recognized and have a great reputation. Although the ranking may change due to time and market conditions, the following brands are generally considered to be among the top brands in the valve industry: Water System Valves and Industrial ValvesThe following more influential first-line brands can be used as a reference, but are for reference only:

Suzhou Neway Valve, Shanghai Qizhong Valve, Shanghai Guanlong Valve, Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

Categories: Science >> Science >> Engineering Technology Science.

Analysis: What you are talking about is actually called a check valve or a check valve (check valve).

Check valves are only used for one-way opening and closing valves to prevent the reverse flow of fluid media in various pipelines or equipment.

Check valves are widely used and there are many types, and the following are the check valves commonly used for water supply and heat:

1. Spring type: the liquid is from the bottom to the top, relying on the pressure to jack up the spring-controlled valve disc, after the pressure disappears, the spring force will press down the valve disc and close the liquid backflow. It is often used for check valves with small diameters.

2. Gravity type: Similar to the spring type, it relies on the self-gravity closure of the valve disc to prevent backflow.

3. Swing type: the liquid is straight through in the valve body, relying on the pressure to open the side of the rotary valve disc rock resistance, after the pressure is lost, the valve disc relies on its own weight to return to position, and the reverse liquid pressure closes the valve disc.

The principle of other check valves (check valves), such as the check valve for blowdown, the explosion-proof valve for civil air defense and the check valve for liquid use, is similar.

There is also the following information:

Check valve (check valve).

Check valve, also known as check valve, commonly known as single-flow valve, can be automatically opened according to the pressure difference between the front and back of the valve, and the function is to automatically control the flow direction of the liquid, so that it flows in one direction and prevents it from flowing in the opposite direction. Check valves are mostly used in water supply pipelines, and they must not be installed in reverse direction when installed.

Lift check valve. The upper part of the valve core of this valve has a guide rod, the guide rod and the valve core can be freely lifted along the guide sleeve on the valve cover, when the fluid flows from left to right, the valve core is pressed open, and when the fluid flows in the opposite direction, the valve core descends to the valve seat, and the passage is cut off.

The rocking plate check valve, also known as the swing check valve, is slightly the same as the lifting type.

The above two check valves are only installed on the horizontal line.

Spring-loaded check valve, this kind of valve is the development of the lifting type.

Ordinary lift check valves can only be installed on horizontal pipes, while spring lift check valves can be free of direction restrictions. It is used in both horizontal pipes, vertical pipes and pipes at a certain angle.

Spring-loaded check valves. These valves are available in sizes 15 mm (1 2 in) to 50 mm (2 in).

Foot valve. It is a kind of one-way valve specially installed at the inlet of the suction pipe of the water pump, commonly known as the bottom of the well, the shower head, etc.

Backflow preventer is a combination device of hydraulic control valve, which can strictly limit the one-way flow of pressurized water in the pipeline and effectively prevent backflow pollution.

According to the tap water supply equipment, especially the domestic drinking water pipeline backflow pollution is serious, and there is no effective backflow prevention device, the backflow preventer is developed to strictly limit the water in the pipeline can only flow in one direction, and its function is to prevent the medium in the pipeline from backflow under any working conditions, so as to achieve the purpose of avoiding backflow pollution.

At present, the backflow preventer is mainly divided into two categories: low-resistance backflow preventer and decompression backflow stopper, according to the national standard, the head loss of low-resistance backflow preventer is less than 3 meters, and the head loss of decompression backflow preventer is less than 7 meters. Backflow preventers can be divided into pressure-reducing backflow preventers, low-resistance backflow preventers and double-check valve backflow preventers, among which the pressure-reducing backflow preventers are suitable for all anti-backflow pollution situations, but the resistance is larger.

Notes:

1. The backflow preventer with the air balance ridge (such as the pressure-reducing backflow preventer mentioned above) may introduce external pollution, so when the fire water supply system adopts this kind of backflow preventer, it should be set up in a clean and sanitary place, and the drainage should take technical measures to prevent it from being flooded.

2. The resistance loss of the backflow preventer is large, and the impact of the resistance loss needs to be reviewed when applied.

The pressure-reducing backflow preventer is composed of two independent check valves and a hydraulically controlled drain valve, which can strictly limit the one-way flow of pressurized water in the pipeline and effectively prevent backflow pollution.

The backflow preventer product consists of two separated check valves and a hydraulically driven drain valve. Due to the local head loss of the check valve, the pressure in the intermediate chamber is always lower than the pressure at the inlet. This differential pressure drives the drain valve to be closed and the pipeline to supply water normally.

When the pressure is abnormal, (i.e., the pressure at the outlet end is higher than that of the intermediate cavity), even if the two check valves cannot be sealed in reverse, the safety drain valve can automatically open to empty the backflow water and form an air partition to ensure the health and safety of the upstream water supply.

Generally speaking, this type of valve is suitable for clean water or in piping systems with physical and chemical properties similar to clean water and does not allow the medium to flow backwards. For example:

1. The intersection of the domestic drinking water pipeline and the connected pipeline for non-domestic drinking water (fire protection, production, irrigation, environmental protection, sprinkling, etc.).

2. Municipal tap water is connected to the user's water outlet near the user's water meter.

3. On the pipe when the water floods the outlet of the water supply pipe.

4. On the suction pipe on the drinking water pipeline of the pressurized pump or multi-type pressurized equipment in series.

5. In the drinking water pipeline network of various buildings and the pipelines that do not allow the backflow of medium in production.

How does a backflow preventer prevent backflow and prevent water from being contaminated? The internal structure of the valve was dismantled.

Is it an electric current or a stream of water?

The current is made with a diode.

Check valves are used for water flow.

The backflow preventer is a check valve that can be installed according to the diameter of the pipe and the way of connection.

The quota is a standard for the amount of resources consumed to complete the qualified products of the unit under the conditions of rational labor organization and rational use of materials and machinery, and it reflects the level of social productivity in a certain period. For each construction project, the amount of labor is calculated, including basic labor and other labor. Plus the materials for this project, including basic materials and other materials.

The unit price of labor is stipulated locally according to the value of labor of different types of work at that time, and the value of materials is based on the budget formulated by the market in the early stage.

Install the relevant valve quota of the water supply and drainage chapter in the budget project quota, and replace the main material.

The water pipe network is connected to the user's household pipe behind the water meter.

The domestic water pipeline is connected to the non-domestic water and sewage pipes, and is installed at the beginning of the outlet pipe.

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

When the pressure pump is connected in series on the drinking water pipe, it is installed on the suction pipe of the pump.

Backflow Preventer Installation Requirements:

The backflow preventer must be installed horizontally, the environment of the installation site should be clean, there should be enough maintenance space, and the main degree of the safety drain or (air barrier) outlet from the ground should be greater than 300mm, and it should not be flooded by water or debris.

Drainage facilities should be provided in the installation area.

Gate valve (butterfly valve) filter and rubber soft joint (or telescopic) should be installed in front of the valve, and gate valve (butterfly valve) should be installed after the valve.

The backflow preventer is a wax grinding device wheel closure bucket that is composed of a state of non-return parts to prevent the backflow of water from the water supply pipeline.