Overview, definition and difference between safety valve and relief valve

1. Overview Safety valves are important safety accessories for boilers, pressure vessels, and other pressure equipment. Its operational reliability and performance are directly related to the safety of equipment and humans, and are closely related to energy conservation and environmental protection. However, some users and design departments always choose the wrong model when selecting a model. For this reason, this article analyzes the selection of safety valves. To

2. Definitions The so-called safety valve includes relief valves in a broad sense. From the perspective of management rules, it is directly installed on a steam boiler or a type of pressure vessel. The necessary condition is that the valve must be approved by the technical supervision department, which is called in a narrow sense. Safety valves, others are generally called relief valves. The safety valve and the relief valve are very similar in structure and performance. Both of them automatically discharge the internal medium when the opening pressure is exceeded to ensure the safety of the production device. Because of this inherent similarity, people often confuse the two when using them. In addition, some production devices also stipulate that either can be used in the rules. Therefore, the difference between the two is often overlooked. Therefore, many problems have arisen. If you want to make a clearer definition of the two, you can understand it according to the definition set out in the first chapter of the “ASME Boiler and Pressure Vessel Code”:

(L) Safety Valve An automatic pressure relief device driven by the static pressure of the medium in front of the valve. It is characterized by a sudden full opening action. Used in gas or steam applications. To

(2) Relief Valve (Relief Valve) Also known as a relief valve, an automatic pressure relief device driven by the static pressure of the medium in front of the valve. It opens proportionally as the pressure exceeds the opening force. Mainly used in fluid applications.

(3) Safety Relief Valve (Safety Relief Valve) Also known as a safety relief valve, an automatic pressure relief device driven by the pressure of the medium. It can be used as both a safety valve and a relief valve according to different applications. Take Japan as an example. There are relatively few clear definitions for safety valves and relief valves. Generally, safety devices used for large energy storage pressure vessels such as boilers are called safety valves, which are installed on pipelines or other facilities. It is a relief valve. However, according to the regulations of the Ministry of International Trade and Industry’s “thermal power generation technology”, the important part of the equipment safety protection is designated to use safety valves, such as boilers, superheaters, and reheaters. Where the lower side of the pressure reducing valve needs to be connected to the boiler and the turbine, a relief valve or safety valve needs to be installed. In addition, from the Japanese Ministry of Labor’s high-pressure gas management rules, the Ministry of Transport, and the rules of the shipping associations at all levels, we refer to the safety valve that guarantees the discharge as a safety valve, and we do not guarantee it. The discharge valve is called a relief valve. Regardless of whether the full lift type or the slightly lifted type is collectively referred to as a safety valve in China.