The function of a safety valve

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The function of safety valves is to prevent the pressure of the medium in pipelines or devices from exceeding specified values, thereby achieving safety protection. A safety valve is a safety protection valve whose closing element remains closed under the influence of external forces. When the pressure of the medium inside equipment or piping rises above a specified value, the valve automatically opens, allowing the medium to be discharged outside the system and thereby preventing the pressure from exceeding the permissible limit. Safety valves belong to the category of automatic valves and are primarily used in boilers, pressure vessels, and pipelines to ensure that pressure does not exceed specified levels, thereby playing a vital role in protecting both human safety and the proper operation of equipment. Based on the opening height of the safety valve disc, they can be divided into slightly opened safety valves and fully opened safety valves. The opening stroke height of slightly opened safety valves is: ≤0.05do (minimum discharge throat diameter) ； The opening height of a fully open safety valve is ≤0.25do (minimum discharge throat diameter). Based on their structural design, safety valves can be classified into pendulum type, lever type, spring type, and pilot (pulsation) type ； Based on the valve body structure, they can be divided into closed and open types. A closed-type safety valve prevents the discharged medium from leaking outside; it directs all of the fluid to a designated location through its outlet, and is generally used with toxic and corrosive media. For safety valves used for air and steam, non-enclosed safety valves are commonly employed. The selection of safety valve products should be determined based on the actual sealing pressure. For spring-loaded safety valves, there are springs available in several operating pressure levels within a certain nominal pressure (PN) range. When placing an order, in addition to specifying the valve model, name, medium, and temperature, it is also necessary to indicate the sealing pressure of the valve body; otherwise, the valve will be supplied at its maximum sealing pressure. The following points should be noted regarding the installation and maintenance of safety valves: All types of safety valves should be installed vertically. There should be no resistance at the outlet of the safety valve to prevent pressure buildup. The safety valve should be tested specifically before installation, and its sealing performance should be checked. Safety valves in use should be inspected regularly.