The safety valve is a special valve that is in a normally closed state under the action of external force. When the pressure of the medium in the equipment or pipeline rises beyond the specified value, it discharges the medium to the outside of the system to prevent the medium pressure in the pipeline or equipment from exceeding the specified value. . Safety valves are automatic valves, mainly used in boilers, pressure vessels and pipelines. The control pressure does not exceed the specified value, which plays an important role in protecting personal safety and equipment operation. NOTE The safety valve must be pressure tested before it can be used.
Safety valve installation should meet the following requirements
1. For boilers with rated evaporation greater than 0.5t/h, at least two safety valves shall be installed: for boilers with rated evaporation less than or equal to 0.5t/h, at least one safety valve shall be installed. Safety valves are installed at the outlet of the separable economizer and the outlet of the steam superheater.
2. The safety valve should be installed vertically at a high position of the boiler and the header. Between the safety valve and the drum or header, no outlet pipes and valves for taking steam shall be installed.
3. The pilot-operated safety valve must have a device to prevent the weight from moving on its own and a guide frame to limit the lever derailment. The spring-type safety valve must have a lifting handle and a device to prevent the adjustment screw from being arbitrarily twisted.
4. For boilers with rated steam pressure less than or equal to 3.82MPa, the throat diameter of safety valve should not be less than 25mm: for boilers with rated steam pressure greater than 3.82MPa, the throat diameter of safety valve should not be less than 20mm.
5. The cross-sectional area of the connecting pipe between the safety valve and the boiler shall not be less than the cross-sectional area of the inlet 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 less than 1.25 times the exhaust area of all safety valves.
6. The safety valve should generally be equipped with an exhaust pipe, and the exhaust pipe should go straight to the safe place and have a sufficient cross-sectional area to ensure smooth exhaust. The bottom of the exhaust pipe of the safety valve should be equipped with a cavity. There is a drain pipe connected to a safe place. Valves are not allowed to be installed on the exhaust pipe and the drain pipe.
The safety valve plays a safety protection role in the system. When the system pressure exceeds the specified value, the safety valve is opened, and part of the gas/fluid in the system is discharged into the atmosphere/pipeline, so that the system pressure does not exceed the allowable value, thereby ensuring that the system does not cause an accident due to excessive pressure.