Ball valves and gate valves are two different types of valves. Their differences are as follows: 1. Valve core structure
The valve core of the ball valve is a sphere. Due to its fixed ball structure, the valve ball is fixed under high pressure, especially when it is closed. Its upper stem and lower pivot decompose part of the pressure from the medium, so The valve ball does not deflect downstream, so the pressure on the downstream valve seat is relatively small. Therefore, the friction the valve overcomes when operating is small, and the wear of the valve seat is small. The service life of the valve is long, especially for valves that frequently operate. This structure is more suitable.
The valve core of the gate valve is a wedge-shaped valve plate or a parallel valve plate. There is no pivot at its lower part. Therefore, when the valve is under high-pressure application and in the closed state, the valve plate withstands great pressure from the medium. Due to its flat valve plate structure, all the medium pressure acts on the valve plate at the same time, and the valve plate It will press hard to the downstream valve seat (at the same time, excessive pressure acts on the vertical surface of the valve plate, which will cause the valve plate to have a certain deformation whether it is wedge-shaped or parallel double gate plate), and the valve needs to be opened when it is opened. To overcome the great friction, the wear of the valve seat will shorten the life of the valve.
2. Valve seat structure
There is a spring inside the valve seat of the ball valve, and the sealing design of the valve seat makes it difficult for debris in the medium to enter the valve seat. The valve seat is in long-term contact with the valve ball under the action of the spring. When the valve moves, the valve seat has a certain scraper effect, which can scrape off the residue attached to the valve core after long-term operation, thus ensuring the sealing performance of the valve for a long time. . Especially in high temperature and high pressure applications, because the materials of the valve seat, valve body, and valve ball are selected with the same thermal expansion coefficient, as well as the valve seat with spring structure, when the valve is closed, there will be a huge temperature difference and temperature drop. , will not affect the action of the valve, and the valve will not lock.
The valve seat of the gate valve is very narrow. When the valve is closed in high-temperature applications, the temperature drops because the medium does not flow, so the valve seat will tighten, thus exerting a large pressing force on the valve plate. When the valve is opened again, a large torque is required to overcome this pressing force, which will cause great damage to the valve seat and affect the life of the valve seat. This affects the service life of the valve. In addition, due to the self-weight of the gate itself when the valve is closed, it will bring a great impact to the valve and make a lot of noise.
3. Itinerary
The stroke of the ball valve is angular stroke, so the installation space is small and the height is low. The stroke of the gate valve is a straight stroke, so the installation space is large and the height is high.
4. Execution agency
Due to the fixed ball design of the ball valve, its opening and closing torque values are small, so the actuator is correspondingly small. Due to the large pressing force of the valve plate on the valve seat of the gate valve, a huge torque is required to overcome this large friction, so the actuator must be equipped with a large size.