1. Operating principle of safety valve
Down on the disc spring pre-tightening force of Fd, part of the resistance to medium force Po. S, another part of the produce valve seal between compaction force f, with the improvement of medium pressure, seal between the clamping force each other less, when the medium pressure to open Ps, mutual compression force is zero, the relief valve opens, meet at this time: Fd = Ps. S
2. Safety valve related standards
Because of the importance of safety valves, many standards and regulations have been formulated for the design and manufacture of safety valves around the world.China's early safety valve standards refer to the former Soviet union safety valve standards.Current safety valve standards are:
GB/ t12241-89 (general safety valve requirements) GB/ t12242-89 (safety valve performance test method)
GB/ t12243-89 (spring-loaded safety valve)
API520/API526/API527 (U.S. standard)
3. Safety valve calibration and maintenance
In order to comprehensively test all technical performance indexes of the safety valve, it is necessary to conduct a full performance test.In addition to high temperature and high pressure vessels and other equipment, this test device also has a rapid measuring instrument with various parameters, and ensures a large flow of high temperature and high pressure steam source, which is costly.
Calibration is a part of safety valve test, and it is the main item of factory test.The open pressure setting and sealing test of air media are usually carried out with the normal temperature safety valve test bench before leaving the factory.Safety valve normal temperature test bench can only do open pressure setting and sealing test.