The opening and closing parts of gate valve, globe valve and ball valve are different, and the sealing principle is different. The opening and closing part of the gate valve is the gate, the movement direction of the gate is perpendicular to the direction of the fluid, and the gate valve is sealed through the contact between the valve seat and the valve plate. The opening and closing part of the globe valve is a plug-shaped valve disc, and the sealing surface is a plane or sea cone surface, and the valve disc moves linearly along the center line of the valve seat. It seals by applying torque to the valve stem, which applies pressure to the disc in the axial direction. The sealing surface of the valve disc and the sealing surface of the valve seat are tightly fitted to prevent the medium from leaking along the gap between the sealing surfaces. The opening and closing parts of the ball valve are driven by the valve stem and rotate around the axis of the ball valve to seal.
