A safety valve having a double safety function is provided to increase accuracy and precision of an operation pressure by considerably reducing leakage, malfunction, and hunting of a sheet. A safety valve(100) having a double safety function includes a nozzle(1), a disk holder(4), a pipe line(200), a pressure switch, a solenoid, and an air pressure driver(23). The nozzle is adhered on the pipe line, is contacted to fluid inside the pipe line, and directly receives an inside pressure. The disk holder containing a disk forms a sheet by contacting an upper part of the nozzle. The pressure switch is electrically connected with the pipe line, detects an inside pressure, and outputs an electrical signal by comparing the detected pressure and a predetermined pressure. The solenoid is opened and closed by the electrical signal. The air pressure driver is interlocked with the solenoid and operates the safety valve.
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