The opening and closing part of the cast steel gate valve is a gate plate. The direction of movement of the gate plate is perpendicular to the direction of the flow. The gate valve can only be fully opened and fully closed, and adjustment and throttling cannot be performed. The ram has two sealing surfaces. The two sealing surfaces of the most commonly used mode ram valves form a wedge, and the wedge angle varies with the valve parameters, typically 50, and 2° 52′ when the medium temperature is not high. Wedge gate valve gate can be made into a whole, called the rigid gate; can also be made of a slight deformation of the gate, in order to improve its craft, to make up for the deviation of the sealing surface angle in the process, this kind of brake The board is called a flexible shutter.
1.Before installation, check the inside of the valve cavity and the sealing surface, and do not allow any dirt or sand particles to adhere; 2.Where the bolts of each connection site require uniform tightening; 3.Check the packing site requirements for compaction to ensure the tightness of the packing. It is also necessary to ensure that the gate is flexible; 4. Before the valve is installed, the user must check the valve model, the connection size and the flow direction of the medium to ensure consistency with the valve requirements. 5. The user must reserve the valve driver when installing the valve. Necessary space; 6. The wiring of the driving device must be carried out according to the circuit diagram; 7. The valve must be maintained regularly, and it must not be crushed and squeezed freely so as not to affect the sealing.
Gate valve sealing principle is divided into automatic sealing and forced sealing. When the cast steel gate valve is closed, the sealing surface can be sealed only by medium pressure, that is, relying on the medium pressure to press the sealing surface of the gate plate to the valve seat on the other side to ensure the sealing of the sealing surface. This is automatic sealing. When the valve is closed, it is necessary to force the gate plate to press against the valve seat by external force to ensure the sealing of the sealing surface. This is a forced seal. Domestic high pressure gate valves use automatic sealing, and low pressure gate valves use the principle of forced sealing.
Note: The self-sealing structure of the high-pressure gate valve is different from the automatic sealing principle mentioned above. The self-sealing structure means that the connection structure between the middle of the gate valve and the valve cover is a self-sealing structure, which is different from the forced sealing of the middle of the low-pressure medium pressure valve. Flange connection. The middle part of the gate valve in the figure below is a forced-seal flange connection structure. The valve body and the valve cap are tightly connected by bolts, while the central part of the gate valve in the self-sealing structure is without bolts. Below PN160 pressure is a flanged forced seal; PN160 pressure is used above the self-sealing structure gate valve.