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    Home > Active Ingredient News > Drugs Articles > Structure analysis diagram of spring group elastic valve seat

    Structure analysis diagram of spring group elastic valve seat

    • Last Update: 2014-10-30
    • Source: Internet
    • Author: User
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    Spring group elastic valve seat is a kind of valve sealing structure which evenly arranges a group of compression springs on the cross-section circumference of the valve fluid channel, and makes the seal ring and the ball contact closely by the spring thrust, so as to achieve the pre tightening sealing effect When the spring group elastic seat is used in the fixed ball valve, the elastic seat shall be arranged before and after the valve of the ball valve This arrangement can realize the front sealing, back sealing and double-sided back sealing of the ball valve when the relevant geometric parameters of the ball valve are changed For these three sealing forms, the structure is similar but the characteristics are different, which can meet different work needs Therefore, spring group elastic valve seat is used in fixed ball valve, regardless of high temperature, low temperature and ordinary temperature 2 Spring group elastic seat spring group elastic seat is a valve sealing structure which uses spring group to achieve pre tight contact seal and relies on fluid pressure to achieve seal The specific structure diagram is shown in Figure 1 1 Valve body 2 Spring 3 Seat sealing ring 4 Valve seat 5 Ball sealing ring 6 Ball Figure 1 spring group elastic valve seat, where d 1 is the middle diameter of the valve body contact surface; D 2 is the middle diameter of the ball contact surface The relationship between D 1 and D 2 is the key to determine the three sealing forms of spring group elastic seat When d 1 > D 2, the spring group elastic seat is the front sealing seat; when d 1 < D 2, the spring group elastic seat is the back sealing seat; when d 1 > D 2; d 1 '< D 2', the spring group elastic seat is the double sealing seat 2.1 When d 1 > D 2, the spring set elastic seat is the spring set valve front sealing elastic seat structure, as shown in Figure 2 At this time, the fluid pressure area A1 of the valve seat is larger than the reverse pressure area A2 of the ball sealing ring At this time, under the action of spring pre tight sealing force and differential pressure thrust of fluid on A1 and A2 pressure surfaces, the ball sealing ring is tightly attached to the ball to achieve the sealing of the valve At this time, the valve back seat does not play a sealing role Fig 2 spring group valve front seal elastic seat for valve back seat structure, there is no clear provisions Its design needs to be determined according to the pressure relief form of the valve body cavity For the pressure relief fluid before discharging to the valve, a large part of the cavity fluid of this structure can not be eliminated due to the pressure of the fluid in the valve body After the pressure relief fluid is discharged to the valve, when the valve is closed, the lower downstream pressure can remove most of the fluid in the body cavity When the pressure relief fluid is discharged to the valve back structure, the structure of the valve back seat must adopt the structure that the pressure area A3 of the valve seat in the cavity is larger than that A4 of the valve seat outside the cavity, as shown in Figure 3 Fig 3 structure of valve back seat: D 1 '> D 2'; a 3 > a 4 When the pressure of the middle chamber increases, the pressure area A3 of the fluid valve seat is larger than the reverse pressure area A4 of the valve seat Under the action of the differential pressure thrust of the fluid, the seal of the ball and the ball is pushed open, and the high-pressure middle chamber fluid is discharged into the pipeline behind the valve to achieve pressure relief For the valve front seat seal, its advantages: the stuffing box, bonnet and most valve bodies of the valve do not bear the pressure of the fluid; there is no large amount of medium in the valve body cavity to corrode the packing, bonnet, etc.; when the body cavity is accidentally pressurized, the fluid can be discharged quickly, avoiding the impact on the valve; there is no liquid accumulation area behind the valve Therefore, the valve seat seal in front of the valve is particularly suitable for corrosive media and low-temperature liquid gasification occasions Disadvantages: when the sealing force acts on the ball, the torque load required to rotate the ball is large, and the valve stem is subject to large driving force; the calculation accuracy of the specific pressure of the seal is high, and when the specific pressure of the seal is too large, the valve seat overload and the rotating torque of the ball will be large; when the specific pressure of the seal is small, the valve seat seal will fail; it can only be used within a certain pressure range 2.2 rear seal of spring group elastic seat when D 2 > d 1, the spring group elastic seat is the rear seal elastic seat structure of spring group valve, as shown in Figure 4 Fig 4 when d 1 > D 2, the fluid pressure area a 1 of the front valve seat is smaller than the reverse pressure area a 2 of the ball sealing ring At this time, under the pressure differential thrust of pressure surfaces a 1 and a 2, the fluid pushes the ball seal ring away from the ball, creating a fluid gap channel, and the fluid enters the body cavity of the ball valve The pressure area a 3 of the valve seat is smaller than the pressure area a 4 The medium entering the middle chamber will generate differential pressure thrust on the pressure surfaces A3 and A4, and the rear seat sealing ring will be tightly attached to the ball to achieve the sealing of the valve For the rear seal spring group, the structure of the front valve seat and the rear valve seat are basically the same Front valve seat: D 1 < D 2; a 1 < a 2 Rear valve seat: D 1 '< D 2'; a 3 < a 4 For the valve back seat seal, its advantage: the fluid enters into the body cavity and uses the back seat seal Therefore, the effective force of the fluid pressure on the ball and the valve seat is small, the torque required for the rotation of the ball is small, and the bearing force of the stem shaft is also small Therefore, it is suitable for high pressure large diameter occasions The bearings are self-lubricating Disadvantages: the fluid always exists in the body cavity, which is disadvantageous to the sealing of the packing, the valve cover and the valve body; it is not suitable to control the corrosive fluid; it cannot be automatically relieved, and the pressure relief device must be set when it is used in the low-temperature liquid gasification situation; to fully ensure D2 > D1, it is necessary to reduce the flow pipe diameter or increase the size of the ball and the valve body 2.3 when d 1 > D 2; d 1 '< D 2', the spring group elastic seat is the spring group double-sided seal elastic seat structure, as shown in Figure 5 Fig 5 spring group double face seal elastic seat spring group double face seal elastic seat is actually the combination of spring group elastic seat valve front and valve back seal Front valve seat: D1 > D2; A1 > A2; rear valve seat: D1 '< D2'; A3 < A4 In this way, whether there is no fluid in the body cavity or more or less fluid in the body cavity will produce the phenomenon that the fluid pressure is higher or lower than that in the pipeline, the sealing effect of the ball sealing ring on the valve can be realized For the double-sided seat seal, its advantages: reliable sealing performance; there will always be more or less fluid into the cavity, producing a certain pressure on the ball, the seat, the ball's rotating torque load is small Therefore, it is used in places with high sealing requirements Disadvantages: double face seat seal can not achieve automatic pressure relief Therefore, pressure relief device must be set when controlling liquefied gas Conclusion the spring group elastic seat of fixed ball valve is a kind of sealing structure involving high, low and common temperature, which is widely used The characteristics of the three types of sealing structure are different, so it is necessary to choose the right sealing structure in application The seal pressure ratio is affected by the driving force of the pressure difference of the pressure area, the spring force of the pretension spring and the sliding friction force At the same time, it is greatly affected by the driving force of the pressure difference of the pressure area However, the size of the middle diameter of the two compression surfaces is generally similar So the calculation must be carried out in the design (1) the relationship between the diameter d 1 of the valve body contact surface and the diameter D2 of the ball contact surface determines the three sealing forms of the valve (2) the sealing specific pressure (i.e the reliability of sealing) of the spring group elastic valve seat of the fixed ball valve mainly depends on the proportional relationship between the diameter D1 of the valve body contact surface and the diameter D 2 of the ball contact surface (3) for the three sealing structures, the front valve seat seal can be used in the corrosion and liquefied gas with pressure P ≤ 10MPa and the occasions with large valve diameter; the rear valve seat seal is usually used in the 80-100 diameter valve with pressure P ≥ 16MPa; the double-sided seal is especially used in the dangerous places with high sealing requirements Technical supply of three fine valves
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