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How to select Triple Eccentric Butterfly Valve
发布时间：2018-10-23 来源：艾德威尔•瑞拓
Butterfly valves can be divided into central butterfly valves, single eccentric butterfly valves, double eccentric butterfly valves and Triple Eccentric Butterfly Valve according to their structural types. This paper will study their structural characteristics and application occasions.
Center butterfly valve
Structural features: the center of the stem, the center of the butterfly plate and the center of the body are in the same position, as shown below.
Advantages: simple structure, easy manufacture, common lining butterfly valve is the same.
Disadvantage: Because butterfly plate and valve seat are always in the state of extrusion and scraping, high resistance moment and fast friction, in order to overcome extrusion and scraping, and ensure sealing performance, the valve seat is basically made of elastic materials such as rubber or PTFE, so it is limited by operating temperature (silicone rubber: - 60 ~ 200', PTFE: - 30 ~ 180', PEEK: - 46 ~ 280').
Taking a brand of central butterfly valve as an example, its caliber range is DN50-DN1200, nominal pressure < PN16, suitable for normal temperature, high temperature and low pressure air or other low pressure gas control.
Two. Single eccentric butterfly valve
Structural features: the stem axis deviates from the center of the butterfly plate, as shown below.
Advantages: dispersing relieves the excessive extrusion of the upper and lower ends of the butterfly plate and the valve seat.
Disadvantage: Because the single eccentric structure in the entire valve switching process, butterfly plate and seat scratch phenomenon has not disappeared, in the scope of application and the center butterfly valve is not much different, so the use of less.
The double eccentric butterfly valve is further improved on the basis of the single eccentric butterfly valve.
Structural features: the stem axis deviates from the center of the butterfly plate and deviates from the center of the body, as shown in the following figure.
For specific action, you can refer to the following Animation:
Advantages: The double eccentricity effect makes the butterfly plate break away from the valve seat quickly after the valve is opened, eliminating the unnecessary excessive extrusion and scraping between the butterfly plate and the valve seat, reducing the wear and tear, improving the valve life, greatly reducing the scrape, and at the same time making the double eccentricity butterfly valve can also use the metal seat to improve the valve life. Application of butterfly valve in high temperature field.
Disadvantage: Dual eccentric valve is through the butterfly plate squeeze valve seat caused by the elastic deformation of the sealing effect, belongs to the line seal, so it is used in closed position requirements are not high, low pressure capacity occasions.
Take a brand double eccentric butterfly valve as an example, its caliber range is DN50-DN1200, and the pressure level is less than PN40.
Four, three eccentric butterfly valves
Three the eccentric butterfly valve has been reconstructed on the basis of the structure of the double eccentric butterfly valve.
Structural Features: The stem axis deviates from both the butterfly plate center and the body center; the conical axis of the butterfly plate seal surface deviates from the body cylinder axis, belonging to the face seal, as shown in the following figure.
Advantages: fundamentally changed the sealing structure, is no longer a position seal, but a torsional seal, that is, not rely on the elastic deformation of the seat, but entirely rely rely rely rely on the contact surface of the seat to achieve sealing effect, so it solved the problem of zero leakage of the metal valve seat at one stroke, and because the pressure of the contact surface is proportional to the pressure of the medium, high temperature resistance. The pressure is readily solved.
In this paper, the application scope of various structural valves is based on a domestic brand of Triple Eccentric Butterfly Valve, not excluding the special application of other brand products.
Center butterfly valve
Structural features: the center of the stem, the center of the butterfly plate and the center of the body are in the same position, as shown below.
Advantages: simple structure, easy manufacture, common lining butterfly valve is the same.
Disadvantage: Because butterfly plate and valve seat are always in the state of extrusion and scraping, high resistance moment and fast friction, in order to overcome extrusion and scraping, and ensure sealing performance, the valve seat is basically made of elastic materials such as rubber or PTFE, so it is limited by operating temperature (silicone rubber: - 60 ~ 200', PTFE: - 30 ~ 180', PEEK: - 46 ~ 280').
Taking a brand of central butterfly valve as an example, its caliber range is DN50-DN1200, nominal pressure < PN16, suitable for normal temperature, high temperature and low pressure air or other low pressure gas control.
Two. Single eccentric butterfly valve
Structural features: the stem axis deviates from the center of the butterfly plate, as shown below.
Advantages: dispersing relieves the excessive extrusion of the upper and lower ends of the butterfly plate and the valve seat.
Disadvantage: Because the single eccentric structure in the entire valve switching process, butterfly plate and seat scratch phenomenon has not disappeared, in the scope of application and the center butterfly valve is not much different, so the use of less.
Take a single eccentric butterfly valve as an example, its caliber is DN650-DN2700.
The double eccentric butterfly valve is further improved on the basis of the single eccentric butterfly valve.
Structural features: the stem axis deviates from the center of the butterfly plate and deviates from the center of the body, as shown in the following figure.
For specific action, you can refer to the following Animation:
Advantages: The double eccentricity effect makes the butterfly plate break away from the valve seat quickly after the valve is opened, eliminating the unnecessary excessive extrusion and scraping between the butterfly plate and the valve seat, reducing the wear and tear, improving the valve life, greatly reducing the scrape, and at the same time making the double eccentricity butterfly valve can also use the metal seat to improve the valve life. Application of butterfly valve in high temperature field.
Disadvantage: Dual eccentric valve is through the butterfly plate squeeze valve seat caused by the elastic deformation of the sealing effect, belongs to the line seal, so it is used in closed position requirements are not high, low pressure capacity occasions.
Take a brand double eccentric butterfly valve as an example, its caliber range is DN50-DN1200, and the pressure level is less than PN40.
Four, three eccentric butterfly valves
Three the eccentric butterfly valve has been reconstructed on the basis of the structure of the double eccentric butterfly valve.
Structural Features: The stem axis deviates from both the butterfly plate center and the body center; the conical axis of the butterfly plate seal surface deviates from the body cylinder axis, belonging to the face seal, as shown in the following figure.
Advantages: fundamentally changed the sealing structure, is no longer a position seal, but a torsional seal, that is, not rely on the elastic deformation of the seat, but entirely rely rely rely rely on the contact surface of the seat to achieve sealing effect, so it solved the problem of zero leakage of the metal valve seat at one stroke, and because the pressure of the contact surface is proportional to the pressure of the medium, high temperature resistance. The pressure is readily solved.
In this paper, the application scope of various structural valves is based on a domestic brand of Triple Eccentric Butterfly Valve, not excluding the special application of other brand products.
