Manual valves are commonly used on equipment and devices. They are operated by a handle or handwheel. Under normal circumstances, handle, hand wheel rotation clockwise thorium provisions for the closing direction, counterclockwise rotation is specified as the opening direction. However, some of the valve opening and closing direction contrary to the above, to help check the operation before opening and closing signs and then operate.
Manual valve, the handle, hand wheel size is designed for normal people. Therefore, the use of the provisions of the valve: do not allow the operator with the lever and long wrench Kai, close the valve. At the same time the handle length, hand wheel diameter less than 320mm, only promised to operate a person; diameter equal to or more than 320mm hand wheel, promised to work together, or promised to use a suitable lever (usually no more than 0.5m) operation. However, the diaphragm valve, non-metallic valve is prohibited to use the lever or long wrench operation, do not answer too large, too much force to close the valve.
Some operators are accustomed to using the lever and long wrench to operate the manual valve, that the greater the closing force, the better, but it is not. This will cause premature valve damage, and even lead to accidents. Practice has proved that: In addition to the impact of the hand wheel, the valve is too large to easily operate the hand wheel, handle, abrasion stem and sealing surface, or even crush the sealing surface. Second, the handwheel, the handle is damaged or lost, it should be timely with, do not agree to use live wrench substitution.
Valve such as gate valve and stop valve, turn off or open to the end (ie, bottom dead center or top dead center) to be rotated 1/4 ~ 1/2 laps, so that the thread closer together to facilitate the operation of inspection to avoid twist Tight damage to the valve.
Larger diameter butterfly valve, gate valve and globe valve, some with bypass valve. The role of bypass valve is to balance the import and export pressure, reduce the opening torque. Open, you should open the bypass valve, and then open the large valve.
Before opening the steam valve, the pipe must be preheated to discharge condensate water. Open slowly, to avoid water hammer, damage to valves and equipment. Open and close the ball valve, butterfly valve, plug valve, when the top of the stem groove and the channel parallel, indicating that the valve fully open position; when the valve to the left or right 90 degrees, the groove perpendicular to the channel, Indicates the valve is in the fully closed position. Some ball valves, butterfly valves, plug valves with wrench and channel parallel to open, vertical to close. Three-way, four-way valve operation should be opened, closed, reversing the mark, the operation should be removed after the active handle.
On the center of the gate valve and throttle valve, should check to adjust the fully open or fully closed indication position. Ming rod valve, globe valve should also employ them fully open and fully closed position, so as to avoid the top dead-end. When the valve is fully closed, it can be found by means of the ruler and markings that the closing piece is off or withstands the foreign matter in order to eliminate the fault.
Newly installed pipes and equipment, the inside dirt, welding slag and other objects more. Normally open manual valve sealing surface easily sticky dirt, the use of micro-open method, so that high-speed media washed away these foreign bodies, and then gently shut down.
Some manual valves in the closed, the temperature dropped, valve contraction, the sealing surface to produce a small gap, a leak. This should be closed again at an appropriate time after closure.
Valve operation is correct or not, a direct impact on valve life.
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