The safety valve is normally closed under the action of external force. When the medium pressure in the equipment or pipeline rises above the specified value, the medium is discharged to the outside of the system to prevent the medium pressure in the pipeline or equipment from exceeding the specified value. . Safety valves belong to the category of automatic valves, which are mainly used in boilers, pressure vessels and pipelines. The control pressure does not exceed the specified value and plays an important role in protecting personal safety and equipment operation. Note that the safety valve must be pressure tested before it can be used.
The safety valve is a special branch of the valve family. Its particularity is because it is different from other valves which only play a role of switching, and more importantly, it plays a role in protecting the safety of the equipment. With the rapid development of my country's economic construction, there are more and more equipment projects with pressure control. In view of the need for equipment to relieve pressure, safety valves play a vital role in protecting the equipment.
The safety valve installation should meet the following requirements:
1. Boilers with a rated evaporation capacity greater than 0.5t/h should be equipped with at least two safety valves; boilers with a rated evaporation capacity less than or equal to 0.5t/h should be equipped with at least one safety valve. Safety valves must be installed at the outlet of the separable economizer and the steam superheated.
2. The safety valve should be installed vertically at the higher position of the boiler and header. Between the safety valve and the drum or header, there shall be no outlet pipes and valves for taking steam.
3. The lever-type safety valve must have a device to prevent the heavy hammer from moving by it and a guide frame to limit the lever's deviance and the spring-type safety valve must have a device to lift the handle and prevent the adjustment screw from being twisted casually.
4. For boilers with rated steam pressure less than or equal to 3.82MPa, the safety valve throat diameter should not be less than 25mm; for boilers with rated steam pressure greater than 3.82MPa, the safety valve throat diameter should not be less than 20mm.
5. The cross-sectional area of the connecting pipe between the safety valve and the boiler should not be less than the inlet cross-sectional area of the safety valve. If several safety valves are installed together on a short pipe directly connected to the drum, the passage cross-sectional area of the short pipe should not be 1.25 times the exhaust area of all safety valves.
6. The safety valve should generally be equipped with an exhaust steam pipe, which should directly lead to a safe place and have sufficient cross-sectional area to ensure smooth exhaust. The bottom of the safety valve exhaust pipe should be equipped with a cavity and a drain pipe connected to a safe place. Valves are not allowed on the exhaust pipe and the drain pipe.