What are the characteristics of the butterfly valve, and what occasions are it suitable for

Butterfly valves are suitable for flow regulation. Because the pressure loss of the butterfly valve in the pipeline is relatively large, about three times that of the gate valve, when selecting the butterfly valve, the influence of the pressure loss of the pipeline system should be fully considered, and the firmness of the butterfly plate to bear the pressure of the pipeline medium when it is closed should also be considered. In addition, the limitations of the operating temperature to which the resilient seat material can withstand at high temperatures must also be considered.

The structural length and overall height of the butterfly valve are small, the opening and closing speed is fast, and it has good fluid control characteristics, and the structural principle of the butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to be used to control the flow rate, it is important to select the correct size and type of butterfly valve so that it can work properly and effectively.

In general, in throttling, regulation control and slurry media, short structural length and fast opening and closing speed (1 4 revolutions) are required. Low pressure cut-off (small pressure difference), butterfly valve is recommended. Butterfly valves can be used when there is a small amount of leakage into the atmosphere and abrasive medium in the case of double-position adjustment, necked ground channel, low noise, cavitation and gasification, a small amount of leakage to the atmosphere, and abrasive medium.

When the butterfly valve is used under special working conditions, such as throttling adjustment, or strict sealing, or serious wear, low temperature (cryogenic) and other working conditions, it is necessary to use a special butterfly valve with metal seal with adjustment device. The midline butterfly valve is suitable for fresh water, sewage, seawater, salt water, steam, natural gas, food, medicine, oil and various acids and alkalis and other pipelines that require complete sealing, zero gas test leakage, high life requirements, and working temperature of -10 degrees to 150 degrees. The soft-seal eccentric butterfly valve is suitable for two-way opening and closing and adjustment of ventilation and dust removal pipelines, and is widely used in gas pipelines and waterways in metallurgy, light industry, electric power, and petrochemical systems.

Metal-to-metal wire sealed double eccentric butterfly valve is suitable for urban heating, gas supply, water supply and other gas, oil, acid and alkali pipelines, as a regulating and throttling device. In addition to being used as a program control valve for large-scale pressure swing adsorption (PSA) gas separation devices, metal-to-metal sealed triple eccentric butterfly valves can also be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other fields, and are a good alternative to gate valves and globe valves.

The valve is particularly suitable for gases and slurry liquids with low differential pressure, large diameter and high flow rates. For the general control valve DN300mm is the large valve, only a few to DN450, and for the butterfly valve, DN500 is below the small valve, DN500 1000 is the medium size valve, the largest butterfly valve diameter can reach 9m. It can be seen that the regulating valve used in large-diameter pipelines is mainly butterfly valves.

Butterfly valve (English: butterfly valve) refers to a kind of valve that turns around the valve shaft to open and close the closing part (valve disc or butterfly plate) as a disc, which mainly plays the role of cutting off and throttling on the pipeline. The butterfly valve opening and closing part is a disc-shaped butterfly plate, which rotates around its own axis in the valve body, so as to achieve the purpose of opening and closing or adjusting.

The butterfly valve is usually less than 90° when fully open to fully closed, and the butterfly valve and the butterfly rod itself do not have the ability to self-lock, so in order to position the butterfly plate, a worm gear reducer should be installed on the valve stem.

The use of worm gear reducer can not only make the butterfly plate have the ability to lock itself, make the butterfly plate stop in any position, but also improve the operation performance of the valve. The characteristics of the industrial butterfly valve can withstand high temperatures, the applicable pressure range is also high, the valve nominal diameter is large, the valve body is made of carbon steel, and the sealing ring of the valve plate is made of metal ring instead of rubber ring. The large high-temperature butterfly valve is made of steel plate welding, which is mainly used for flue air ducts and gas pipelines of high-temperature medium.

Structure: It is mainly composed of valve body, valve stem, disc plate and sealing ring. The body is cylindrical, with a short axial length and a built-in plate.

Hello! Neither of these valves is very suitable for granular media, which is easy to get stuck in it and is not wear-resistant! It is recommended to use a metal hard-sealed butterfly valve, which is wear-resistant and high-temperature resistant.

Butterfly valves are used in a wide range of applications and are suitable for flow regulation. Due to the large pressure loss of the butterfly valve in the pipeline, it is about 3 times that of the gate valve. Therefore, when selecting butterfly valves, the influence of pressure loss in the pipeline system should be fully considered, and the firmness of the butterfly plate to withstand the pressure of the pipeline medium when it is closed and the limitation that the elastic seat material can withstand the working temperature at high temperatures should also be considered.

The structural length and overall height of the butterfly valve are relatively small, the opening and closing speed blocks, have good fluid control characteristics, and its architectural principle is most suitable for making large-diameter valves. When a butterfly valve is required to be used to control the flow rate, it is important to choose the correct size and type of butterfly valve so that it can work more efficiently.

In general, in throttling, regulation control and slurry media, short structural length and fast opening and closing speed are required. For low pressure cut-off, butterfly valves are recommended.

1. Butterfly valve can be used when the channel of double adjustment, necking, low noise, cavitation and gasification, a small amount of leakage to the atmosphere, and corrosive medium.

2. When the butterfly valve is used under special working conditions such as throttling adjustment or strict sealing, or serious wear and low temperature, it is necessary to use a special butterfly valve with a special metal seal with an adjustment device.

3. In addition to being used as a program control valve for large-scale pressure swing adsorption gas separation device, metal-to-metal sealing triple eccentric butterfly valve can also be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other fields, and is a good alternative product for gate valves and globe valves.

4. The midline butterfly valve is suitable for fresh water, sewage, seawater, salt water, steam, natural gas, food, medicine, oil and various acids and alkalis and other pipelines that require complete sealing, zero gas leakage, high life requirements, and a working temperature of -10-150 degrees.

5. Metal-to-metal wire sealed double eccentric butterfly valve is suitable for urban heating, gas supply, water supply and gas, oil, acid and alkali pipelines, as a regulating and intercepting device.

The selection of valves is mainly based on the flow characteristic curve of the valve, and the valve weight and other parameters. Ball valves are quick opening valves, which are generally used in situations where there is quick opening and closing, and the pipe diameter is relatively small. The gate valve has low resistance, good airtightness after closing, and less internal leakage, and is often used for the shut-off of the main pipe; The globe valve has large resistance and high valve weight, so it is more suitable to adjust the flow rate at the end; The disc valve is small in size, and the shape of the disc can be adjusted to design the valve with different flow characteristics.

The main basis for the selection of the valve is that the requirements of the pipeline system should be adapted to the flow characteristic curve of the valve, generally speaking, the globe valve is mainly used for the adjustment of the flow rate, but its own resistance is large, and the packing is easy to leak; The resistance of the gate valve is small and the shut-off is good, but it is not conducive to the regulation of the flow rate; Ball valves are suitable for rapid shut-off systems, and generally have a small pipe diameter; The butterfly valve is small in size, combined with the advantages of globe valve and ball valve, it is not only adjustable, but also has good shut-off, and the pipe diameter is relatively large, and the scope of application is relatively wide, divided into hot water and cold water. Classified by use and role.

Cut-off valves are mainly used to cut off or turn on the flow of media. Including gate valves, globe valves, diaphragm valves, ball valves, plug valves, disc valves, plunger valves, ball plug valves, needle instrument valves, etc.

Control valves are mainly used to regulate the flow and pressure of the medium. Including regulating valves, throttle valves, pressure reducing valves, etc.

Check valves are used to stop the backflow of media. Check valves of various constructions are included.

Diverter valves are used to separate, distribute, or mix media. Including distribution valves and traps of various structures. Safety valves are used for safety protection in case of overpressure of the medium. Various types of safety valves are included.

1. The butterfly valve has the characteristics of simple structure, small size, light weight, low material consumption, small installation size, fast switch, 90° reciprocating rotation, small driving torque, etc., and is used for cutting and switching; Regulates the medium in the line with good fluid control characteristics and shut-off sealing performance.

2. The butterfly valve can transport mud and accumulate the least liquid at the mouth of the pipeline. At low pressures, a good seal can be achieved. Good regulation performance.

3. The streamlined design of the butterfly plate makes the fluid resistance loss small, which can be described as an energy-saving product.

4. The valve stem is a through-rod structure, which has good comprehensive mechanical properties, corrosion resistance and scratch resistance after quenching and tempering treatment. When the butterfly valve is opened and closed, the valve stem only rotates and does not lift and fall, and the packing of the valve stem is not easy to be damaged, and the sealing is reliable. It is fixed with the butterfly plate taper pin, and the overhanging end is designed to prevent the valve stem from falling out when the connection between the valve stem and the butterfly plate is accidentally broken.

5. The connection methods include flange connection, clamp connection, butt welding connection and lug clamp connection.

The butterfly valve is characterized by its beauty and generosity, and it is also more convenient to use.

The butterfly valve is characterized by its own requirements.

<> First, the development of butterfly valves: In the 30s, the United States invented the butterfly valve, which was introduced to Japan in the 50s, and was widely adopted in Japan in the 60s, and was promoted in China after the 70s. At present, butterfly valves above DN300 mm in the world have gradually replaced gate valves.

Compared with gate valves, butterfly valves have shorter opening and closing times, smaller operating moments, smaller installation space and light weight. Taking DN1000 as an example, the butterfly valve is about 2T, and the gate valve is about, and the butterfly valve is easy to combine with various driving devices, with good durability and reliability. The disadvantage of the rubber seal butterfly valve is that when it is used for throttling, cavitation will occur due to improper use, which will cause the rubber seat to peel off and be damaged.

In recent years, China has also developed metal sealed butterfly valves, and in recent years, Japan has also developed cavitation-resistant, low-vibration, low-noise comb-shaped butterfly valves. The service life of the general sealing seat is 15-20 years for rubber and 80-90 years for metal under normal conditions. However, how to choose correctly depends on the requirements of working conditions.

Second, the use of butterfly valve depends on the judgment of reed: The relationship between the opening of the butterfly valve and the flow rate is basically a linear proportional change. If it is used to control the flow rate, its flow characteristics are also closely related to the flow resistance of the piping, such as the diameter and form of the valves installed in the two pipelines are the same, and the pipeline loss coefficient is different, the flow rate of the valve will be very different.

If the valve is in a state of large throttling, the back of the valve plate is prone to cavitation, and there is a possibility of damaging the valve, so it is generally used outside 15°. When the butterfly valve is in the middle opening, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and the two sides are formed to complete different states, the front end of the butterfly plate on one side moves in the direction of flowing water, and the other side moves against the direction of flowing water, therefore, the valve body and the valve plate on one side form a nozzle-shaped opening, and the other side is similar to the throttle hole-shaped opening with an opening, and the nozzle side is much faster than the flow rate on the throttle side, and negative pressure will be generated under the valve on the throttle side, and the rubber seal will often fall offThe operating torque of the butterfly valve, due to the different opening and opening and closing directions of the valve, the value is different, and the torque generated by the horizontal butterfly valve, especially the large-diameter valve, due to the water depth, the torque generated by the difference between the upper and lower head of the valve shaft can not be ignored.

In addition, when an elbow is installed on the inlet side of the valve, a deflection flow is formed, and the torque increases. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of the water flow torque.

There are many ways to classify butterfly valves, and they are divided into soft seal butterfly valves and hard seal butterfly valves according to their sealing materials.

Soft Seal Butterfly Valve: The sealing pair is composed of non-metallic soft materials to non-metallic soft materials, or metal hard materials to non-metallic soft materials.

Hard Seal Butterfly Valve: The sealing pair is composed of a metal hard material against a metal hard material.

Difference Between Soft Seal Butterfly Valve and Hard Seal Butterfly Valve:

1. Soft seal butterfly valves are mostly centerline type hard seals, and most of them are single eccentric, double eccentric, and triple eccentric butterfly valve structures.

2. Soft seal is used in room temperature environment. Hard seals can be used in low temperature, normal temperature, high temperature and other environments.

3. The soft seal is used for low pressure-normal pressure, and the hard seal can also be used for medium and high pressure.

4. The sealing performance of soft seal and triple eccentric hard seal butterfly valve is relatively good, and the triple eccentric butterfly valve can maintain a good seal in the high pressure and high temperature environment.

Because of their different characteristics, soft seal butterfly valves are suitable for two-way opening and closing and adjustment of ventilation and dust removal pipelines, water treatment, light industry, petroleum, chemical and other industries. Hard seal butterfly valves are mostly used in heating, gas supply, gas, oil, acid and alkali environments.