Description of the working principle of the ball valve
The ball valve is evolved from the cock. Its opening and closing part is a sphere, which uses the sphere to rotate 90o around the axis of the valve stem to achieve the purpose of opening and closing. The ball valve is mainly used for cutting
The ball valve designed as a V-shaped opening also has a good flow regulation function. The ball valve is not only simple in structure, good in sealing performance, but also in a certain nominal
The range is small in size, light in weight, low in material consumption, small in installation size, and small in driving torque, easy to operate, and easy to realize fast opening and closing.
The ball valve is most suitable for direct opening and closing, but recent developments have designed the ball valve to throttle and control the flow. The main feature of the ball valve is its compact structure, easy operation and maintenance, suitable for general working media such as water, solvent, acid and natural gas, and also suitable for media with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene.
Analysis of the advantages of ball valves
1. Small fluid resistance: Ball valves generally have two structures: reduced diameter and non-reduced channels. No matter what kind of structure the ball valve has a relatively small flow resistance coefficient. Especially the so-called full flow type, that is, a reduced diameter ball
Valve, since its channel diameter is equal to the inner diameter of the pipe, the local resistance loss is only the frictional resistance of the same length of pipe, that is, the flow resistance of this kind of ball valve is the smallest among all valves. In rocket launch and
In its test system, the resistance of the pipeline is required to be as small as possible. There are two ways to reduce the resistance of the pipeline system. One is to reduce the fluid flow rate. For this reason, it is necessary to increase the pipe diameter and the valve retreat diameter, which
The economy of the pipeline system will often have an adverse effect, and it is extremely unfavorable to the cryogenic transportation system (liquid hydrogen); one is to reduce the local resistance of the valve, so the ball valve is naturally the best choice.
2. The switch is fast and convenient: because the ball valve in general factory only needs to turn the handle to complete the fully open to fully closed action, it is easy to achieve rapid opening and closing.
3. Good sealing performance: At present, most of the valve seats of ball valves are made of elastic materials such as polytetrafluoroethylene, and the sealing pair composed of metal and non-metal materials is usually called a soft seal. Generally speaking
Now, the tightness of the soft seal is easy to guarantee, and the requirements for the machining accuracy and surface roughness of the sealing surface are not very high.
4. Long life: Because PTFE has good self-lubricating properties, the friction and wear with the ball is small, and due to the improvement of the ball processing technology, the roughness is reduced, thereby increasing the service life of the ball valve.
5. High reliability: The high reliability of the ball valve is mainly due to
(1) The pair of seals of the ball and the valve seat will not suffer from scratches, sharp wear and other failures, and will not get stuck during work (in the absence of lubricant
Time), so it can be reliably applied to corrosive media and low boiling point liquids;
(2) The built-in valve stem structure eliminates the potential accident risk that the valve stem may fly out due to the loosening of the packing gland under the action of fluid pressure;
(3) The ball valve with anti-static and fire-resistant structure is suitable for pipelines that transport oil, natural gas, and gas.
