Regardless of the type of valve manufacturer, the sealing surface is most likely to be damaged, and plug injuries, touch injuries, and crush injuries will occur during switching. Under the action of high pressure, the forged steel ball valve can easily cause the atoms on the seal to penetrate each other and cause adhesion.
If the two covers move, there will be adhesion and pulling, especially when the surface of the cover of the solenoid valve of the hydraulic pump is rough, the pulling is more likely to occur. In the sealing process of the forged steel ball valve, if there is any contact or extrusion damage, it will cause local wear or indentation on the sealing surface.
During the working process, the medium is easy to cause abrasion, washing, cavitation and other consequences on the sealing surface, which is called "medium erosion". This situation often causes local damage, so the quality of the sealing surface must be handled properly. Under the alternating action of medium erosion and chemical erosion of the large-diameter solenoid valve, this is the strong corrosion of the sealing surface.
In addition to natural damage, there are also man-made damages on the sealing surface. The reasons for man-made damage are: improper design, poor manufacturing, improper material selection, improper installation, improper use, insufficient maintenance and many other factors; therefore, these must be avoided. Only when the situation occurs can the ball valve be used without any problems and the service life of the ball valve can be guaranteed.
With the construction of large-scale national projects, the supply of electric power, petroleum, chemical, urban water supply, drainage systems and other valves is increasing, especially the use of butterfly valves is greater, so the direct-acting type encountered by users in use There are more and more problems with solenoid valves. Here, I will summarize the frequently occurring problems to guide the correct installation and use. I hope it will be helpful to everyone.
The main problems faced by domestic hard-sealed butterfly valves are as follows:
Since the multi-layer soft and hard laminated sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium will wash the sealing surface of the valve plate positively, and the soft sealing band in the metal sheet sandwich will directly affect the sealing performance after being washed.
Restricted by structural conditions, valves below DN200 are not suitable for this structure, because the overall structure of the valve plate is too thick and the flow resistance is large.
Due to the principle of the triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is driven by the torque of the transmission device to press the valve plate against the valve seat. In the normal flow state, the greater the medium pressure, the tighter the seal extrusion; as the medium pressure increases, when the flow channel medium flows in the reverse direction, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal will be A leak has occurred.
At present, the country has no corresponding special standards for the flanges of elastic hard-sealed butterfly valves. According to the current national standards, we adopt the socket-type inner warp type under the condition that the standard size of the flange remains unchanged. The inner diameter of the flange is basically the same as the nominal passage, which not only increases the effective sealing surface, but also provides advantageous convenience for installation, and at the same time ensures the normal use of the valve.