For valves, it is necessary not only to be able to install and regularly maintain and maintain, but also to be able to operate. Under normal circumstances, the opening and closing of the valve follows the principle of "reverse opening and closing", that is, the counterclockwise rotating handwheel is an open valve, and the clockwise rotating handwheel is a closed valve.
(1) Whether it is an electric valve or a pneumatic valve, the manual function is generally considered in the valve planning, and the manual function of the valve is generally realized through the hand wheel or handle. The handwheel or handle of the valve is planned according to ordinary manpower, taking into account the strength of the sealing surface and the necessary sealing force. Therefore, it is not possible to use a long lever or a long wrench to pull it during the opening and closing operation of the practical valve. Some people are accustomed to using the "F" wrench, should pay strict attention, do not use too much force, otherwise simply damage the sealing surface, or break the handwheel, handle, for part of the bevel gear or worm gear transmission of the valve, choose an extended lever or "F" wrench to operate the handwheel, too much force may lead to the bevel gear or worm gear deformation or damage.
(2) When opening and closing the valve, the force should be stable and not bumping. Some parts of the high-pressure valve that choose to open and close the bumper handwheel have been considered in the planning and manufacturing of this impact force, which cannot be equivalent to the general valve.
When the valve is fully opened, the handwheel should be reversed a small amount to make the threads tight to avoid loose damage. For open rod valves, it is necessary to remember the orientation of the valve stem when it is fully open and fully closed, so as to check whether the valve condition is normal when it is fully open and fully closed, assuming that the valve disc falls off, or a large debris is embedded between the valve core and the sealing surface of the valve seat, the valve stem orientation when the valve is fully open and fully closed will be changed, and the fault can be found very easily in order to take further measures in time.
(3) When the pipeline is first used, there are many internal debris, the valve can be slightly opened, the high-speed activity of the medium can be used to wash it away, and then quietly closed (can not be closed quickly, violently closed, in order to prevent residual impurities from pinch the sealing surface), open again, repeat many times, flush out the dirt, and then put into normal operation.
(4) Normally open valves, there may be dirt sticking on the sealing surface, and they should be washed clean with the above methods when closed, and then officially closed. If the handwheel and handle are damaged or lost, they should be equipped immediately, and should not be replaced by a flexible wrench to avoid damage to the valve stem and the opening and closing, resulting in accidents in production.
Some medium, after the valve is closed, cooled, so that the valve is shortened, the operator should be closed again at the appropriate time, (4) let the sealing surface leave no fine seams, otherwise, the medium flows through the fine seams at high speed, and it is very simple to erode the sealing surface.
(5) When operating the valve, if it is found that the operation is too laborious, the cause should be analyzed, and the operation should not be forced. If the filler is too tight, it can be relaxed appropriately; If the stem is tilted, the maintenance personnel should be told to repair it. If it is necessary to open at this moment, the bearing gland on the valve cover can be loosened half a turn to one turn to eliminate the stress of the valve stem, and then turn the handwheel.
(6) When operating the high-pressure valve, due to the very high pressure of the high-pressure valve pipeline, the pressure difference between the front and rear of the valve is very large when driving, so the operation must be very careful, and it should be gradually opened when it is open. First open a little bit, so that the high-pressure fluid gradually fills the pipeline behind the valve, and when the front and rear pressure is close, the valve opening should be adjusted according to the specified flow rate. If the system is equipped with a bypass valve, the bypass valve should be opened before the main valve is opened, and the large high-pressure valve on the main pipeline should be opened when the front and rear pressures are close to equilibrium.
(7) Wedge gate valves and globe valves are only fully open or fully closed, and are not allowed to be used for conditioning and throttling, so as to avoid sealing failure caused by erosion or shorten the service life of the valve.
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