What are the valve seal grades? How do we usually choose valves according to the seal grade

The sealing grade of the valve usually refers to the reliability of the valve seal, that is, the ability of the valve to prevent the leakage of the working medium in the closed state. Common valve seal grades include the following:
Zero leakage: When the valve is closed, it can completely prevent the working medium from leaking out, which is the highest sealing grade.
Tight leakage: When the valve is closed, there is only a small leak, which will not affect the working environment and equipment.
Micro-leakage: When the valve is closed, there will be a certain degree of leakage, but it will not have a serious impact on the working environment and equipment.
Obvious leakage: When the valve is closed, there will be a large leak, which will have a significant impact on the working environment and equipment.
According to different working environments and requirements, it is very important to choose the right valve seal grade. In general, the higher the sealing grade of the valve, the price will also increase accordingly. Therefore, the selection of the appropriate valve seal grade needs to consider many factors, such as the characteristics of the working medium, working pressure, working temperature, environmental requirements. It is recommended that when purchasing valves, first clarify the working conditions and requirements, and then select the appropriate valve sealing grade and material according to actual needs.