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Structure and characteristics of stop valve

2022-11-21


The metal support surface of the power station stop valve core is designed to match the metal support surface of the valve seat ring, but its contact angle is slightly different. Normally, the valve core has a larger angle than the taper of the valve seat ring. This annular mismatch ensures the contact of a narrow point, and the axial force of all operators is only transmitted to a small part of the valve seat, thus obtaining the possibility of tight metal to metal contact closure. In most configurations, the seat ring of the manual globe valve is screwed into the valve body. It is also required to rotate the valve seat ring with tools in a limited space.
There are also some disadvantages for threaded seats:
First of all, under corrosive or harsh working conditions, the thread will be corroded, making disassembly difficult.
Second, additional grinding is required when aligning the valve core and valve seat.
Another commonly used guide type of manual stop valve is the valve seat guide structure. Here, the valve core rod is supported by an upper guide (it acts as a packing gland). The outer diameter of the valve core head extension serves as the second guide surface to guide the valve seat. This means that the surface of the lower deflector remains in the logistics layer, so the process medium is relatively clean. The lower part of the valve core head is provided with an opening, which enables the material flow to reach the valve seat through the valve core head during the opening process of the valve seat. Changing the size and shape of these openings will affect the reduced flow rate and flow characteristics. Because the length between the upper guide and the lower guide is * * * long, the lateral cock movement caused by the process flow is not a problem, and the allowable deviation required by this type of guide is not as strict as that of the double top stem guide. This structure reduces the chance of any vibration of the valve core during operation. When the valve core and valve seat are made of the same material, metal surface wear may occur during long-term or frequent operation. High temperatures can cause thermal expansion and fatigue.



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