Practical operation method of safety valve

2022-06-22
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The practical operation method of safety valve

to adjust the discharge pressure and reseating pressure of the valve, it is necessary to carry out the action test of the valve reaching the full opening height. Therefore, it can only be carried out on the large capacity test device or after the safety valve is installed on the protected equipment. The adjustment method varies according to the valve structure

for the structure with recoil disc and valve seat adjusting ring, the valve seat adjusting ring is used for adjustment. Unscrew the fixing screw of the adjusting ring, extend a tool such as a thin iron bar from the exposed screw hole, and then move the specified cutter teeth of the wheel on the adjusting ring to make the adjusting ring roll left and right. When the adjusting ring is rotated counterclockwise to the left, its position will increase, and the discharge pressure and reseating pressure will decrease. On the contrary, when the adjusting ring is rotated clockwise to the right, its position will decrease, and the discharge pressure and reseating pressure will increase. During each adjustment, the rolling range of the adjusting ring should not be too large

before the safety valve leaves the factory, its opening pressure shall be adjusted one by one to the setting value required by the user. If the user proposes the working pressure level of the spring, it shall be adjusted according to the lower limit of the pressure level

before installing the safety valve on the protected equipment or before installation, the user must readjust it on the installation site to ensure that the set pressure value of the safety valve meets the requirements

within the range of spring working pressure level indicated on the nameplate, the opening pressure can be adjusted by rotating the adjusting screw to change the spring compression

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 rotating the adjusting screw, so as to damage the sealing surface

in order to ensure the correct opening pressure value, the medium premise during adjustment, such as medium type and temperature, should be as close as possible to the actual operation premise. When the type of medium changes, especially when the accumulation state of the medium is different (for example, from liquid phase to gas phase), the opening pressure often changes and the clamping force decreases. When the operating temperature increases, the opening pressure generally decreases. Therefore, when it is adjusted at normal temperature and used at high temperature, the set pressure value at normal temperature should be slightly higher than the opening pressure value required by the national automobile industry development policy. How high is related to the valve structure and material selection, which should be based on the manufacturer's instructions

the conventional safety valve is used to fix the additional back pressure. When the opening pressure is adjusted after maintenance (at this time, the back pressure is atmospheric pressure), its setting value shall be the required opening pressure minus the additional back pressure

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