(1) Adjustment of opening pressure
① Before the Gate Valve leaves the factory, its opening pressure should be adjusted one by one to the setting value required by the user. If the user proposes a spring working pressure level, the factory adjustment should generally be made according to the lower limit of the pressure level.
② Before installing the Gate Valve on the protected equipment or before installation, the user must readjust it at the installation site to ensure that the set pressure value of the Gate Valve meets the requirements.
③ Within the spring working pressure level range indicated on the nameplate, the opening pressure can be adjusted by changing the spring compression amount by rotating the adjusting screw.
④ Before rotating the adjusting screw, the valve inlet pressure should be reduced to less than 90% of the opening pressure to prevent the valve disc from being driven to rotate when the adjusting screw is rotated, thereby damaging the sealing surface.
⑤ In order to ensure the accuracy of the opening pressure value, the medium conditions during adjustment, such as medium type, temperature, etc., should be as close as possible to the actual operating conditions. The opening pressure often changes when the type of medium changes, especially when the accumulation state of the medium is different (for example, from liquid phase to gas phase). As the operating temperature increases, the cracking pressure generally decreases. Therefore, when adjusting at normal temperature and using it at high temperature, the set pressure value at normal temperature should be slightly higher than the required opening pressure value. How high it is is related to the valve structure and material selection, and should be based on the manufacturer's instructions.
⑥Conventional Gate Valve are used when additional back pressure is fixed. When the opening pressure is adjusted after inspection (the back pressure is atmospheric pressure at this time), the setting value should be the required opening pressure value minus the additional back pressure value.
Universal Valve adjustment safety technical operation process
(2) Adjustment of discharge pressure and return pressure
① To adjust the valve discharge pressure and reseating pressure, an action test must be carried out with the valve reaching the full opening height. Therefore, it can only be carried out on a large-capacity test device or after the Gate Valve is installed on the protected equipment. The adjustment method varies depending on the valve structure.
②For the structure with recoil plate and valve seat adjustment ring, the valve seat adjustment ring is used for adjustment. Unscrew the fixing screw of the adjusting ring and insert a thin iron rod or other tool from the exposed screw hole to move the gear teeth on the adjusting ring to make the adjusting ring rotate left and right. When the adjusting ring is rotated counterclockwise to the left, its position increases, and both the discharge pressure and the return pressure will be reduced. On the contrary, when the adjusting ring is rotated clockwise to the right, its position decreases, and both the discharge pressure and the return pressure will increase. Every time you adjust, adjust: the range of rotation of the circle should not be too large (usually a few teeth can be turned). After each adjustment, the fixing screw should be tightened so that its end is located in the groove between the two teeth of the adjusting ring, which can prevent the adjusting ring from rotating and produce no radial pressure on the adjusting ring. For safety reasons, before turning the adjustment ring, the Gate Valve inlet pressure should be appropriately reduced (generally should be lower than 90% of the opening pressure) to prevent the valve from suddenly opening during adjustment and causing an accident.
③ For structures with upper and lower adjustment rings (one adjustment ring each on the guide sleeve and valve seat), the adjustment is more complicated. The valve seat adjusting ring is used to change the size of the channel between the valve disc and the adjusting ring, thereby changing the degree of pressure accumulation in the chamber between the valve disc and the adjusting ring when the valve is initially opened. When the valve seat adjustment ring is raised, the degree of pressure accumulation increases, thereby reducing the proportional opening stage of the valve and reaching sudden rapid opening faster. Therefore, raising the valve seat adjustment ring can reduce the discharge pressure. It should be noted that the valve seat adjustment ring cannot be raised too close to the valve disc. In that case, leakage at the sealing surface may cause the valve to suddenly open prematurely, but because the medium pressure is not enough to keep the valve disc in the open position at this time, the valve disc will close again immediately, so the valve will jump. Valve seat adjustment: The "ring" is mainly used to reduce the proportion of the valve, the opening stage and adjust the discharge pressure. It also affects the return pressure.
(3) Lead seal
After the adjustment of the Gate Valve is completed, it should be sealed to prevent arbitrary changes in the adjusted condition. When renovating a Gate Valve, note the position of the adjusting screw and adjusting ring before disassembling the valve to facilitate adjustment after the reconditioning. After readjustment, it should be sealed again.
