Operation of Manual Valves

Whether the valve is operated correctly or not directly affects the service life, which is related to the smooth production of equipment and devices, and even the safety of the entire system. After the valve is installed, the operator should be able to be familiar with and master the structure and performance of the valve transmission device, and correctly identify the valve direction, opening signs and indication signals. The manual valve is a valve operated by a handle and a handwheel, and is a commonly used valve on equipment pipelines. The rotation direction of its handle and handwheel is clockwise to close, and counterclockwise to open. However, there are also individual valves that are opened in the opposite direction to the above. Therefore, you should pay attention to checking the opening and closing signs before operation. The handwheel and handle on the valve are designed according to normal manpower. Therefore, it is stipulated in the use of the valve that the operator is not allowed to open or close the valve with the help of a lever and a long wrench. If the diameter (length) of the handwheel and handle is less than 320mm, only one person is allowed to operate it. For handwheels with a diameter of ≥320mm, two people are allowed to operate together, or one person can operate the valve with an appropriate lever (generally no more than 0.5m long). However, diaphragm valves, pinch valves, and non-metallic valves are strictly prohibited from using levers or long wrenches to operate, and it is not allowed to close the valve too violently. Valves such as gate valves and globe valves should be turned 1/4 to 1/2 turn when they are closed or opened to the end (that is, the bottom dead center or the top dead center) to make the thread fit better, which is beneficial to check during operation, so as not to screw too much. tight and damage the valve. When opening the valve of the steam medium, the pipeline must be preheated to remove the condensed water. When opening, it should be carried out slowly to avoid water hammer and damage to the valve and equipment. Some larger diameter butterfly valves, gate valves and globe valves are equipped with bypass valves, whose function is to balance the pressure difference between the inlet and outlet and reduce the opening force. When opening, the bypass valve should be opened first, and the large valve should be opened after the pressure difference between the two sides of the valve is reduced. When closing the valve, first close the bypass valve, and then close the large valve. When the ball valve, butterfly valve and plug valve are opened, when the groove on the top surface of the valve stem is parallel to the channel, it indicates that the valve is in the fully open position; when the valve stem rotates 90° to the left or right, the groove is perpendicular to the channel, indicating that the valve is in the fully open position. fully closed position. Some ball valves, butterfly valves and plug valves are opened with the wrench parallel to the channel, and closed vertically. The operation of the three-way and four-way valves should be carried out according to the marks of opening, closing and reversing. After the operation is completed, the movable handle should be removed. When operating the valve, the gate valve, globe valve and other valves cannot be used as throttle valves, which will easily erode the sealing surface and cause the valve to be damaged prematurely. The newly installed pipes, equipment, valves, internal dirt, welding slag and other debris are more likely to stick to the sealing surface of the normally open valve. The slightly opening method should be used to allow the high-speed medium to wash away these foreign objects, and then light Close lightly. After several times of opening and closing slightly, it can be washed clean. For gate valves and throttle valves with scales, check and debug the fully open or fully closed indicating position. The rising stem gate valve and globe valve should also remember their fully open and fully closed positions, so as to avoid hitting the dead point when fully open. When the valve is fully opened, it can be found that the closing piece falls off or resists foreign objects with the help of rulers and marks, so as to troubleshoot. After some valves are closed, the temperature drops and the valve parts shrink, resulting in small gaps on the sealing surface and leakage. In this way, the valve should be closed again at an appropriate time after closing. If you have any questions, you can consult Lianke Valve Co.,Ltd., which is a Shanghai high-tech enterprise dedicated to valve scientific research, valve product development, valve manufacturing, valve sales, and valve after-sales service. It is a famous trademark enterprise in Shanghai. It is one of the top 20 anti-corrosion pressure pipeline enterprises in China. Contact: +86-577-8585 9626 or 57609878.
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