Classifications of Ball Valves
Classifications of ball valves
The ball valve can be divided into floating ball valves, fixed ball valves, flexible ball valves and oil-sealed ball valves according to the structure. It can be divided into straight ball valves, angle ball valves and three-way ball valves according to the channel. The three-way ball valve can be divided into T-shaped ball valves and L-shaped ball valves. It can be divided into threaded connection ball valves, flanged connection ball valves and welded ball valves according to the connection method.
1. Floating ball valves
The ball of the ball valve is floated. Under the action of medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure that the outlet end is sealed.
The floating ball valve has a simple structure and good sealing performance, but the ball bears the load of the working medium and all the loads are transferred to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball medium. When impacted by high pressure, the ball may shift. This structure is generally used for medium and low-pressure ball valves.
2. Fixed ball valves
The ball of the ball valve is fixed and does not move under pressure. The fixed ball valves are equipped with the seats of floating valves. After the medium pressure, the valve seats will move. They make the seal ring tightly pressed on the ball to ensure the sealing. Generally, the upper and lower shafts of the ball are equipped with bearings. The operating torque is small, which is suitable for high-pressure and large-diameter valves.
In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil-sealed ball valves have appeared in recent years, which not only inject special lubricating oil between the sealing surfaces to form an oil film. It not only enhances the sealing performance but also reduces the operating torque. It is more suitable for high-pressure and large-caliber ball valves.
3. Elastic ball valves (i.e. rail ball valves)
The ball of a ball valve is elastic. The ball and valve seat seal ring are made of metal materials. The specific pressure of the sealing is very high. The pressure of the medium itself cannot meet the sealing requirements, so the external force must be applied. This valve is suitable for high-temperature and high-pressure mediums.
The elastic sphere obtains elasticity by opening an elastic groove at the lower end of the inner wall of the sphere. When the channel is closed, use the wedge head of the valve rod to expand the ball and compress the valve seat to seal. Loosen the wedge head before rotating the ball. The ball will return to its original shape so that there is a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
4. V-type ball valves
This kind of ball valve is a fixed ball valve and it is a single-seat sealed ball valve. Its adjustment performance is the best among the ball valves. The flow characteristics are equal in percentage. The adjustable ratio is 100:1. The V-shaped notch has a shearing effect between the seat of metal valves. It is especially suitable for media containing fibers, small solid particles, slurry, etc.
5. Three-way ball valves
Three-way ball valves are available in T type and L type. T-shape 3-way ball valves can make the three orthogonal pipelines connect with each other and cut off the third channel. It plays the role of diversion and confluence. The L-type 3-way ball valve can only connect two mutually orthogonal pipelines. It cannot keep the third pipeline connected at the same time. It only plays the role of distribution.
Notes for installation and maintenance of the ball valve
1. The ball valve should be provided with the position where the handle rotates.
2. The ball valve cannot be used as a throttle.
3. The ball valve with the drive mechanism should be installed vertically.
The ball valve can be divided into floating ball valves, fixed ball valves, flexible ball valves and oil-sealed ball valves according to the structure. It can be divided into straight ball valves, angle ball valves and three-way ball valves according to the channel. The three-way ball valve can be divided into T-shaped ball valves and L-shaped ball valves. It can be divided into threaded connection ball valves, flanged connection ball valves and welded ball valves according to the connection method.
1. Floating ball valves
The ball of the ball valve is floated. Under the action of medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure that the outlet end is sealed.
The floating ball valve has a simple structure and good sealing performance, but the ball bears the load of the working medium and all the loads are transferred to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball medium. When impacted by high pressure, the ball may shift. This structure is generally used for medium and low-pressure ball valves.
2. Fixed ball valves
The ball of the ball valve is fixed and does not move under pressure. The fixed ball valves are equipped with the seats of floating valves. After the medium pressure, the valve seats will move. They make the seal ring tightly pressed on the ball to ensure the sealing. Generally, the upper and lower shafts of the ball are equipped with bearings. The operating torque is small, which is suitable for high-pressure and large-diameter valves.
In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil-sealed ball valves have appeared in recent years, which not only inject special lubricating oil between the sealing surfaces to form an oil film. It not only enhances the sealing performance but also reduces the operating torque. It is more suitable for high-pressure and large-caliber ball valves.
3. Elastic ball valves (i.e. rail ball valves)
The ball of a ball valve is elastic. The ball and valve seat seal ring are made of metal materials. The specific pressure of the sealing is very high. The pressure of the medium itself cannot meet the sealing requirements, so the external force must be applied. This valve is suitable for high-temperature and high-pressure mediums.
The elastic sphere obtains elasticity by opening an elastic groove at the lower end of the inner wall of the sphere. When the channel is closed, use the wedge head of the valve rod to expand the ball and compress the valve seat to seal. Loosen the wedge head before rotating the ball. The ball will return to its original shape so that there is a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
4. V-type ball valves
This kind of ball valve is a fixed ball valve and it is a single-seat sealed ball valve. Its adjustment performance is the best among the ball valves. The flow characteristics are equal in percentage. The adjustable ratio is 100:1. The V-shaped notch has a shearing effect between the seat of metal valves. It is especially suitable for media containing fibers, small solid particles, slurry, etc.
5. Three-way ball valves
Three-way ball valves are available in T type and L type. T-shape 3-way ball valves can make the three orthogonal pipelines connect with each other and cut off the third channel. It plays the role of diversion and confluence. The L-type 3-way ball valve can only connect two mutually orthogonal pipelines. It cannot keep the third pipeline connected at the same time. It only plays the role of distribution.
Notes for installation and maintenance of the ball valve
1. The ball valve should be provided with the position where the handle rotates.
2. The ball valve cannot be used as a throttle.
3. The ball valve with the drive mechanism should be installed vertically.
