Application conditions and operation of Gate Valve

August 13, 2024

A Gate Valve is a valve whose closing part (gate) moves in the vertical direction along the center line of the passage. Universal Valve can only be used for full opening and full closing in pipelines, and cannot be used for adjustment and throttling. Universal Valve are a kind of valve with a wide range of applications. Generally, it is used for cutting devices with a diameter of DN ≥ 50 mm, and sometimes Universal Valve are also used for cutting devices with very small diameters.

The gate has two sealing surfaces. The two sealing surfaces of the commonly used mode 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, called a rigid gate; it can also be made into a gate that can produce a slight deformation to improve its processability and compensate for the deviation of the sealing surface angle during the processing. This gate is called an elastic gate

When the Gate Valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed to the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface. This is self-sealing. Most Universal Valve use forced sealing, that is, when the valve is closed, the gate must be pressed against the valve seat by external force to ensure the sealing of the sealing surface.

The gate of the Gate Valve moves linearly 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 lifting stem, and the rotary 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.

When the valve is opened, when the gate lift height is equal to 1:1 times the valve diameter, the fluid channel is completely unobstructed, but this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position that cannot be opened, as its fully open position. In order to consider the locking phenomenon caused by temperature changes, it is usually opened to the top position and then retracted 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 (i.e., the stroke).

1. Universal Valve are usually used in open-close applications and cannot be used for throttling applications.

2. Universal Valve are usually installed on horizontal pipes with the valve stem pointing vertically upward. They can also be installed on vertical pipes or horizontal pipes where the valve stem is not pointing vertically upward, but special structures may be required depending on the valve diameter, application environment, and material. If the purchased valve is intended to be installed in a special way, the direction of the valve should be stated when ordering.

3. For applications with temperatures exceeding 260°C, it is recommended to use flexible or split wedge gates to prevent the wedge gate from being stuck due to thermal expansion. This may occur when the valve is cold closed and then hot opened.

4. When used for high-speed fluid (turbulent) or thermal cycle applications , in order to avoid loosening, the threaded seat ring should be lock-welded on the valve body. Please specify when ordering.

5. After closing the Gate Valve, the valve stem should be slightly rotated (1/8 to 1/4 turn) to release the stem load. This allows the valve stem to expand slightly without getting stuck or damaging the valve, and will not affect the closing effect.

6. If the seat ring mounting ear handle is removed, the highly integral closing Gate Valve can be used in hot water outlets or piping systems using soft iron. Please specify when ordering.

7. For pump stations that are not restricted by the site, have a lot of debris in the water, and are easy to block important positions, manual and electric dual-purpose Universal Valve can be used; otherwise, butterfly valves can be used, especially in pump room renovation projects, so as to effectively utilize the space of the original pump room and achieve the purpose of increasing the water supply (discharge) volume without changing the original pump room area.

Author:

Mr. Jim

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798905845@qq.com

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+8613193149443