national standard gate valve
I. Product Overview:
Overview of Gate Valves The opening and closing element of a gate valve is the wedge, whose movement direction is perpendicular to the flow direction of the fluid. A gate valve can only be fully opened or fully closed, and is not suitable for regulation or throttling. The wedge has two sealing surfaces; the two sealing surfaces of the most commonly used wedge gate valves form a wedge shape, and the wedge angle varies with valve parameters, usually being 50°. The wedge of a wedge gate valve can be made as a single piece, called a rigid wedge; it can also be made as a wedge that can produce slight deformation, to improve its process performance and compensate for the deviation of the sealing surface angle during processing. This type of wedge is called an elastic wedge. When the gate valve is closed, the sealing surface can be sealed solely by the medium pressure, that is, the medium pressure presses the sealing surface of the wedge against the valve seat on the other side to ensure the sealing of the sealing surface, which is called self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, external force is required to forcibly press the wedge against the valve seat to ensure the sealing performance of the sealing surface. A gate valve in which the wedge moves linearly together with the valve stem is called a rising stem gate valve. Usually, there are trapezoidal threads on the rising stem, and the rotational motion is converted into linear motion through the nut at the top of the valve and the guide groove on the valve body, that is, the operating torque is converted into operating thrust. In some valves, the valve stem nut is located on the wedge, and the handwheel rotates to drive the valve stem to rotate, thereby lifting the wedge. This type of valve is called a rotating stem gate valve or a non-rising stem gate valve.
II. Product Features:
1. Small fluid resistance, and the sealing surface is less subject to scouring and erosion by the medium.
2. Relatively labor-saving to open and close.
3. The medium flow direction is not restricted, with no turbulence and no pressure drop.
4. Simple shape, short structural length, good manufacturing process performance, and wide application range. Types of gate valves: According to the configuration of the sealing surface, they can be divided into wedge gate valves and parallel gate valves. Wedge gate valves can be further divided into single-wedge, double-wedge and elastic-wedge types; parallel gate valves can be divided into single-wedge and double-wedge types. According to the thread position of the valve stem, they can be divided into two types: rising stem gate valves and non-rising stem gate valves.
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