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Dungong Valve (Shanghai) Co., Ltd.

Mobile phone: 13918861646

Telephone: 021-33656988

Mailbox: dungongvalve@163.com

Website: www.sh-dgvalve.com

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Address: No. 5118, Nanfeng Road, Fengxian District, Shanghai

Common problems in the installation and maintenance of gate valves

2020-11-18 10:40:57
Times

The installation and maintenance of the gate valve of the gate valve manufacturer should pay attention to the following matters: Handwheel, handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited. The double gate valve should be installed vertically (that is, the valve stem is in the vertical position and the handwheel is at the top). Gate valves with bypass valves should be opened before opening (to balance the pressure difference between the inlet and outlet and reduce the opening force). The gate valve with transmission mechanism should be installed according to the product manual. If the valve is frequently opened and closed, lubricate it at least once a month. The gate valve is used as a cut-off medium, and the whole flow is straight when it is fully opened. At this time, the pressure loss of the medium is minimal. Gate valves are usually suitable for working conditions that do not need to be opened and closed frequently and keep the gate fully open or fully closed. Not suitable for use as regulation or throttling. For high-speed flowing medium, the gate can cause vibration of the gate when it is partially opened, and the vibration may damage the sealing surface of the gate and the valve seat, and the throttling will cause the gate to be eroded by the medium. From the structural form, the main difference is the form of the sealing element used. According to the form of sealing elements, gate valves are often divided into several different types, such as: wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate valve, etc. The most commonly used forms are wedge gate valves and parallel gate valves.

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The function of this type of valve is to only allow the medium to flow in one direction and to prevent the flow of the direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow. Among them, check valves belong to this type of valve, including swing check valves and lift check valves. The swing check valve has a hinge mechanism and a valve flap like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve clack can reach the proper position of the valve seat surface every time, the valve clack is designed in a hinge mechanism so that the valve clack has enough space for rotation and makes the valve clack truly and comprehensively contact the valve seat. The valve disc can be made of metal, or inlaid with leather, rubber, or synthetic covering, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The valve disc of the lift check valve is seated on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall onto the seat and cut off the flow.

  According to the conditions of use, the valve disc can be an all-metal structure, or it can be in the form of inlaid rubber pads or rubber rings on the disc holder. Like a stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is restricted Rarely.

  In the production process, in order to make the media pressure, flow rate and other parameters meet the requirements of the process flow, it is necessary to install an adjustment mechanism to adjust the above parameters. The main working principle of the adjustment mechanism is to achieve the purpose of adjusting the above parameters by changing the flow area between the valve disc and the valve disc and the valve seat. These types of valves are collectively referred to as control valves, which are divided into self-driving control valves such as pressure reducing valves and stabilizing valves that rely on the power of the medium itself, and those that are driven by power (such as electricity, compressed air and liquid) Power) is called other drive control valve, such as electric control valve, pneumatic control valve and hydraulic control valve.



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