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 a part of the gas in the system is discharged into the atmosphere, so that the system pressure does not exceed the allowable value, so as to ensure that the system does not have an accident due to excessive pressure. Safety valve is also called overflow valve.
Structure Type:
1. Piston safety valve
The valve core is a flat plate. The air source pressure acts on the piston A. When the pressure exceeds the safety value determined by the spring force, the piston A is pushed open, and a part of the compressed air is discharged into the atmosphere from the valve port; when the air source pressure is lower than the safety value, the spring drives The piston moves down, closing the valve port.
2. Ball valve type and diaphragm type safety valve
The working principle is exactly the same as the piston type. These three safety valves are all springs to provide control force, and the safety value can be changed by adjusting the spring preload, so it is called a direct-acting safety valve.
3. Pilot safety valve
A small direct-acting valve is used to provide control pressure on the diaphragm, and the hard core on the diaphragm is the valve core, which is pressed on the valve seat. When the air source pressure A is greater than the safety pressure, the valve core is opened, and the compressed air is discharged into the atmosphere from the left output hole. Diaphragm safety valve and pilot safety valve have good pressure characteristics and sensitive action; but the maximum opening force is relatively small, that is, the flow characteristics are poor. In practical application, the type of safety valve should be selected according to actual needs, and its diameter should be selected according to the maximum exhaust volume.
