Butterfly valve is one kind of regulating and controlling industrial valve, which can realize quick opening and closing through rotating 90°. with simple and compact structure, the manufacturing cost of butterfly valve is relatively low, which is widely used in low pressure pipeline system to regulate and control the flow rate.Â
Types of butterfly valves:Â
According to structure characteristics, butterfly valve can be divided into concentric butterfly valves and eccentric butterfly valves, for eccentric butterfly valves, there are single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve;Â
According to different end connections, concentric butterfly valves can be divided into concentric wafer type butterfly valve, concentric wafer lugged type butterfly valve, concentric flange butterfly valve, welded butterfly valve;Â
With different to sealing material used, there are soft sealing butterfly valve(mostly are concentric soft sealing butterfly valve) and metal hard sealing butterfly valve( most metal hard seal butterfly valves are eccentric butterfly valves); for soft sealing resilient butterfly valves, there are EPDM seated soft sealing butterfly valves, NBR seated soft sealing butterfly valve, PTFE seated soft sealing butterfly valve and FKM seated soft sealing butterfly valve; for metal sealing material, it can be steel seal and copper sealing material;Â
For different body material used in butterfly valves, butterfly valves can be divided into: gray cast iron concentric butterfly valve, cast iron concentric butterfly valve, ductile cast iron concentric butterfly valve, carbon steel concentric butterfly valve(WCB concentric butterfly valve), stainless steel concentric butterfly valve;Â
With different operating actuator used, butterfly valves can be divided into manual lever handle operated butterfly valve, worm gear box operated butterfly valve, electric actuated butterfly valve, pneumatic actuated butterfly valve;Â
According to working pressure, butterfly valves can be divided into vacuum butterfly valve(whose working pressure is lower than standard atmospheric pressure, low pressure butterfly valve( whose working pressure is PN<1.6Mpa), middle pressure butterfly valve( whose nominal pressure is PN2.5-6.4Mpa), high pressure butterfly valve(whose nominal pressure is PN10.0-80.0Mpa), super high pressure butterfly valve( whose nominal pressure is PN>100Mpa);
According to different applicable working temperature, butterfly valves can be divided into super low temperature butterfly valve( whose applicable working temperature T<-100℃), low temperature butterfly valve( whose applicable working temperature -100℃<T<-40℃), normal temperature butterfly valve( whose applicable working temperature -40℃<T<120℃), middle temperature butterfly valve( whose applicable working temperature 120℃<T<450℃), high temperature butterfly valve( whose applicable working temperature T>450℃);
Characteristics of butterfly valves:Â
1. butterfly valve has simple and compact structure and small size, small face to face length, light weight, and is suitable to be made into large diameter valves;
2. Butterfly valve has small fluid resistance; when the butterfly valve is fully opened, the effective flow area of the valve channel is large, and its fluid resistance is small;
3. The butterfly valve can be opened and closed quick and convenient, its adjustment performance is great, through changing the rotating angle of the valve disc, the butterfly valve can realize actuate controlling of the flow rate;
4. Butterfly valve has great sealing performance in low pressure working conditions. The sealing material of soft sealing butterfly valves is generally made of rubber and plastic, which has good sealing performance. With the limit of the sealing materials, the working pressure and temperature range of butterfly valves are low. However, the working pressure and temperature range of the metal hard sealing butterfly valve have been greatly improved;Â
Applications of butterfly valves:Â
Butterfly valves are widely used and are suitable for flow regulating. Due to the large pressure loss of the butterfly valve in the pipeline, which is about 3 times that of the gate valve, therefore, when choosing a butterfly valve, should consider the influence of the pressure loss in the pipeline. And also consider the firmness of the butterfly plate to withstand the pressure of the pipeline medium when the valve is closed, and the limitation of the resilient seal seat material to withstand the high working temperature. The face to face length and the overall height of the butterfly valve are small, it can be opened and closed quickly, and butterfly valve has great flow controlling performance. Butterfly valve is suitable to be made into large diameter valves. When the butterfly valve is required to control the flow rate, it is very important to select the proper diameter and type of the butterfly valve, so to guarantee the selected butterfly valve can work more efficiently.
1. Butterfly valve can be used when the channel with two position adjustment and having low noise, cavitation and gasification, a small amount of leakage to the atmosphere, and having corrosive mediums;
2. When the butterfly valves are required in some special working conditions which need the regulating of the flow rate and strict sealing effect, or have severe wear and low temperature, this butterfly valve should select the special designed specific metal hard sealing double eccentric or triple eccentric butterfly valve with adjusting device;
3. The metal hard sealing triple eccentric butterfly valve can not only used as a controlling valve for a large-scale pressure swing adsorption gas separation device system, also can be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other industrial fields. Metal hard sealing triple eccentric butterfly valve is a good substitute for gate valve, globe valve,etc;
4. The concentric soft sealing butterfly valve is suitable for fresh water, sewage, sea water, salt water, steam, natural gas, food, medicine, oil and various acid-base and other pipelines which requires complete sealing, zero gas leakage, long service life, and working temperature between -10 and 150℃.
5. Metal to metal hard sealing double eccentric butterfly valve is suitable for urban heating, gas supply, water supply and gas, oil, acid and alkali pipelines, as a regulating and cutting-off device;
6. Soft sealing 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 waterway of metallurgy, light industry, electric power, and petrochemical systems.Â
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