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Gate Valve Introduction and Characteristics

A gate valve is a valve in which the closing member (gate) moves vertically along the centerline of the channel. The gate valve can only be used for full opening and full closing in the pipeline, and cannot be used for adjustment and throttling. Gate valve is a valve with a wide range of applications. Generally, it is used for cutting devices with a diameter of DN ≥ 50mm, and sometimes gate valves are also used for cutting devices with small diameters.

The opening and closing part of the gate valve is the gate, and the movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used pattern gate valve form a wedge shape. The wedge angle varies with the valve parameters, usually 50, and 2°52' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, which is called a rigid gate; it can also be made into a gate that can produce a small amount of deformation to improve its manufacturability and compensate for the deviation of the sealing surface angle during processing. The plate is called the elastic gate. Gate valve is the main control equipment for the flow or conveying volume of powder, grain material, granular material and small piece of material. It is widely used in metallurgy, mining, building materials, grain, chemical industry and other industries to control flow change or cut off quickly.

Gate valves specifically refer to the types of cast steel gate valves, which can be divided into wedge gate valves, parallel gate valves, and wedge gate valves according to the configuration of the sealing surface. Gate valve can be divided into: single gate type, double gate type and elastic gate type; parallel gate valve can be divided into single gate type and double gate type. According to the thread position of the valve stem, it can be divided into two types: rising stem gate valve and non-rising stem gate valve.

When the gate valve is closed, the sealing surface can be sealed only by the 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, which is self-sealing. Most of the gate valve is forced seal, that is to say, when the valve is closed, the gate should be pressed to the valve seat by external force, so as to ensure the sealing surface sealing.

The gate of the gate valve moves in a straight line with the valve stem, which is called a lifting stem gate valve (also called a rising stem gate valve). Usually there is a trapezoidal thread on the lifter, and through the nut at the top of the valve and the guide groove on the valve body, the rotating motion is changed into a straight line motion, that is to say, the operating torque is changed into the operation thrust.
When the valve is opened, when the lift height of the gate plate is equal to 1:1 times the diameter of the valve, the passage of the fluid is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a sign, that is, the position where the valve stem does not move is taken as its fully open position. In order to consider the lock-up phenomenon due to temperature changes, usually open to the top position, and then turn back 1/2-1 turn, as the fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate (that is, the stroke).

In some gate valves, the stem nut is set on the gate plate, and the rotation of the hand wheel drives the valve stem to rotate, and the gate plate is lifted. This kind of valve is called a rotary stem gate valve or a dark stem gate valve.


Features of Gate Valve

1. Light weight: the main body is made of high-grade nodular black cast iron, which is about 20%~30% lighter than traditional gate valves, and is easy to install and maintain.
2. The bottom of the elastic seat-sealed gate valve adopts the same flat-bottom design as that of the water pipe machine, which is not easy to cause debris to accumulate and makes the fluid flow unimpeded.
3. Integral rubber covering: the ram adopts high-quality rubber for the overall inner and outer rubber covering. Europe's first-class rubber vulcanization technology enables the vulcanized ram to ensure accurate geometric dimensions, and the rubber and nodular cast ram are firmly bonded, which is not easy Good shedding and elastic memory.
4. Precision cast valve body: The valve body is precision cast, and the precise geometric dimensions make it possible to ensure the tightness of the valve without any finishing work inside the valve body.


Installation and Maintenance of Gate Valves

1. Handwheels, handles and transmission mechanisms are not allowed to be used for lifting, and collisions are strictly prohibited.
2. The double disc gate valve should be installed vertically (that is, the valve stem is in the vertical position and the hand wheel is on the top).
3. The gate valve with a bypass valve should be opened before opening the bypass valve (to balance the pressure difference between the inlet and outlet).
4. For gate valves with transmission mechanisms, install them according to the product instruction manual.
5. If the valve is used frequently on and off, lubricate it at least once a month.

Post time: Aug-07-2023