Unidirectional retroaction electromagnetic valve

A unidirectional retroaction electromagnetic valve connected to a gas meter at a gas inlet, and received a blocking signal and opening signal transmitted form a control circuit for blocking and opening the connection of the gas flow, which uses a battery to supply electric power thereof, comprising:

• a valve body having a first exit, second exit and a communication part communicated with said two exits, which said first exit being is connected to said gas meter and said second exit is connected to a gas hose;
• an O-ring installed at said communication part;
• a manual opening unit used to push a blocking valve plate a first distance through said communication part;
• and
• an electrically controlled blocking unit having a blocking valve plate used to cover said O-ring after receiving said blocking signal in order to block said communication part to form an airtight seal, which pushes said blocking valve plate a second distance after receiving said opening signal;
• when said blocking valve plate being moved said first distance and second distance at the same, said first exit and second exit is completely ventilated.