Pneumatic butterfly valve is one of the main products in industrial automation instruments. Although its structure is relatively simple, its working regulation is very complex in the process pipeline. If there is a problem with the regulating valve, it is also a very troublesome thing to solve, especially if it needs to be replaced, it is more troublesome to transport, Therefore, it is necessary to improve the service life of products.
There are many ways to improve the service life of pneumatic control valves. Here are some examples:
1. Large opening working life extension method
Let the pneumatic control valve work at the maximum opening at the beginning, such as 90%. Thus, cavitation, erosion and other damages occur on the head of the valve element. As the valve core is damaged and the flow increases, the corresponding valve will be closed a little more, so that the whole valve core can be used until the root of the valve core and the sealing surface are damaged and cannot be used. At the same time, the large opening work has large throttling clearance, and erosion is weakened, which increases the service life of the valve by more than 1~5 times than that of the valve in the middle opening and small opening at the beginning.
2. Reducing S, increasing working opening and improving service life
Reduce S, that is, increase the loss of the system except the control valve, so as to reduce the pressure drop distributed to the valve. In order to ensure that the flow passes through the control valve, the opening of the control valve must be increased. At the same time, the pressure drop on the valve decreases, so as to weaken cavitation and erosion. Specific measures include:
① Orifice plate is set behind the valve to throttle the consumption pressure drop;
② Close the manual valve in series on the pipeline until the regulating valve has a better working opening.
3. The method of reducing the diameter and increasing the working opening to improve the service life is to increase the working opening by reducing the diameter of the valve. The specific methods are as follows:
① Change a valve with a smaller diameter, such as DN25 instead of DN32;
② The valve body shall not be changed, and the valve core and valve seat with small valve seat diameter shall be replaced.
4. The method of transferring the damaged position to improve the service life transfers the severely damaged position to the secondary position to protect the sealing surface and throttling surface of the valve core and valve seat.
5. The simplest way to increase the life of the throttling channel is to thicken the valve seat to make the valve seat hole grow and form a longer throttling channel. On the one hand, it can delay the sudden expansion after the flow closed throttling, transfer the damaged position and keep it away from the sealing surface; On the other hand, the throttling resistance is increased, the pressure recovery degree is reduced, and cavitation is weakened. Some designed the valve seat hole as stepped or wavy to increase resistance and weaken cavitation. This method is applied to the high-pressure valve in the imported device and the old valve
It is often used for improvement and is also very effective.
6. Change the flow direction and improve the service life. The open type flows in the open direction. Cavitation and erosion mainly act on the sealing surface, so that the root of the valve core and the sealing surface of the valve core and valve seat are quickly damaged; The flow closed type flows towards the closed direction. Cavitation and erosion act below the sealing surface of the valve seat after throttling, protecting the sealing surface and the root of the valve core, and extending the service life. When the problem of prolonging the service life of the valve used as a flow to open type is more prominent, the service life can be prolonged by 1~2 times by simply changing the flow direction.
7. The method of using special materials to improve the service life is to resist cavitation (such as honeycomb shaped spots) and erosion (streamlined ditches), and special materials resistant to cavitation and erosion can be used to manufacture throttling parts. This special material includes 6YC-1, A4 steel, Stellite, hard alloy, etc. In order to resist corrosion, materials that are more resistant to corrosion and have certain mechanical and physical properties can be used instead. This kind of material is divided into non-metallic materials (such as rubber, tetrafluoro, ceramics, etc.) and metal materials (such as Monel, Hastelloy, etc.).
8. The method of improving service life by changing valve structure adopts the method of changing valve structure or selecting valves with longer service life to achieve the purpose of improving service life, such as selecting multi-stage valves, anti cavitation valves, corrosion resistant valves, etc.
