Introduction to the application of vacuum valves

Manual valves are a type of valve that is used throughout equipment and equipment. It is operated by handles and handwheels. Under normal circumstances, the handle and the handwheel rotate clockwise in the closed direction, and the counterclockwise rotation rule is the open direction. However, some valves open and close in the opposite direction. Before operation, you should pay attention to the opening and closing signs before operating.

For manual valves, the size of the handle and handwheel are planned according to normal people. Therefore, in the valve application rules: do not allow the operator to open and close the valve with the lever and long wrench. With a handle length and hand wheel diameter less than 320mm, only one person is allowed to operate; the hand wheel with a diameter equal to or exceeding 320mm allows the two to operate together, perhaps allowing one to operate with the appropriate lever (the general length does not exceed 0.5m). However, diaphragm valves and non-metallic valves are prohibited from operating with levers or long wrenches, and they do not require excessive or excessive force to close the valve.

Some operators use the lever and the long wrench to operate the manual valve, so that the larger the closing force, the better. This will result in premature valve damage and even become a problem. Practice has proved that in addition to the impact type handwheel, operating the valve too large and excessively damages the hand wheel, the handle, scratches the valve stem and the sealing surface, and even crushes the sealing surface. Secondly, after the handwheel and handle are damaged or lost, they should be timely and not used.

Valves such as gate valves and globe valves should be reversed or opened to the head (ie, bottom dead center or top dead center) to reverse 1/4 to 1/2 turn to make the threads better fit for beneficial operation. Tighten too tightly to damage the valve. Larger diameter butterfly valves, gate valves and globe valves, and some with bypass valves. The function of the bypass valve is to balance the differential pressure between the inlet and outlet and to reduce the open torque. When opening, open the bypass valve and then open the large valve. It is necessary to preheat the pipe and discharge the condensate before opening the steam valve. Be slow when opening to prevent water hammer and damage to valves and equipment.

When opening and closing the ball valve, butterfly valve, and plug valve, when the groove on the top surface of the valve stem is parallel to the passage, the full open position of the valve is indicated; when the valve stem is rotated 90 degrees to the left or right, when the groove is straight with the passage, Indicate that the valve is in a fully enclosed orientation. Some ball valves, butterfly valves, and plug valves are opened in parallel with the wrench and the passage is straight. The operation of the three-way and four-way valves shall be carried out according to the symbols of opening, closing and reversing. After the operation, the movable handle shall be removed.

For the gate valve and throttle valve with the mark, check the indication position of the fully open or fully closed. Open gate valves and shut-off valves should also be used in their fully open and fully closed positions to prevent dead ends when fully open. When the valve is fully closed, the seal can be found to be dropped or against foreign objects by means of the scale and the mark to eliminate the malfunction.

The pipes and equipment of the new installation have many dirt and welds on the inside. The normally open manual valve sealing surface is simply sticky with dirt, and the micro-opening method is used to allow the high-speed medium to wash away these foreign objects and then quietly close. Some manual valves are closed, the temperature drops, and the valve member contracts, causing fine gaps in the sealing surface, showing leakage. This should be closed again at the appropriate time after closure. Whether the valve is operated correctly or not directly affects the service life of the valve.