Safety valve When the medium pressure in the pipeline or equipment exceeds the specified value, the opening and closing parts (valve discs) automatically open to discharge the medium; when the pressure is lower than the specified value, the opening and closing parts (valve discs) automatically close. Valves that protect pipelines or equipment are called safety valves. Safety valves are often used as the last protection device, so their reliability is of great significance to the safety of equipment and people.

(1) Development trend of safety valve The technical development of safety valve has experienced a long process of more than 300 years. From the micro-opening type with small displacement to the full-opening type with large displacement, from the heavy hammer type (static weight type) to the lever heavy hammer type and spring type, after the direct acting type, there is a non-direct acting pilot type. Wait. Its technological development trend generally has the following characteristics.

①The characteristics of standardization and serialization are mainly reflected in the safety valves used in process industries such as petroleum and chemical industries and general industrial boilers. The performance indicators of this type of safety valve have not changed significantly over the years, while its basic parameters have been standardized and serialized. This is mainly reflected in the two aspects of flow channel area and opening height.

a. Flow channel area. Table 2-2 is the standard series of safety valve flow passage area stipulated by the American National Standard ANSIB146.1 "Steel Flange Connection Safety Relief Valve". Shanghai Rongjun Valve manufactures safety valves in strict accordance with the standard. In addition to the United States, Japan, Western Europe, and many other countries have widely adopted the above standard series. Table 2-3 is the standard series of flow passage area stipulated by the former Soviet Union National Standard TOCT12532 "Types and Basic Parameters of Direct-acting Safety Valves".

b. Open height. The national standard of the former Soviet Union [OCT12532] divides the safety valve into the following three types according to the opening height.

Micro-opening type: the opening height is 1/40~1/20 of the diameter of the runner;

Middle opening type: the opening height is greater than 1/20~1/4 of the diameter of the runner;

Full open type: the opening height is greater than 1/4 of the diameter of the runner.